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Secondary Metabolites in Plants




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Secondary metabolites are chemicals produced by plants for which no role has yet been
found in growth, photosynthesis, reproduction, or other "primary" functions. These
chemicals are extremely diverse; many thousands have been identified in several major
classes. Each plant family, genus, and species produces a characteristic mix of these
chemicals, and they can sometimes be used as taxonomic characters in classifying
plants. Humans use some of these compounds as medicines, flavorings, or recreational
drugs.
Secondary metabolites can be classified on the basis of chemical structure (for example,
having rings, containing a sugar), composition (containing nitrogen or not), their
solubility in various solvents, or the pathway by which they are synthesized (e.g.,
phenylpropanoid, which produces tannins). A simple classification includes three main
groups: the terpenes (made from mevalonic acid, composed almost entirely of carbon
and hydrogen), phenolics (made from simple sugars, containing benzene rings,
hydrogen, and oxygen), and nitrogen-containing compounds (extremely diverse, may
also contain sulfur).

The apparent lack of primary function in the plant, combined with the observation that
many secondary metabolites have specific negative impacts on other organisms such as
herbivores and pathogens , leads to the hypothesis that they have evolved because of
their protective value. Many secondary metabolites are toxic or repellant to herbivores
and microbes and help defend plants producing them. Production increases when a
plant is attacked by herbivores or pathogens. Some compounds are released into the air
when plants are attacked by insects; these compounds attract parasites and predators
that kill the herbivores. Recent research is identifying more and more primary roles for
these chemicals in plants as signals, antioxidants , and other functions, so "secondary"
may not be an accurate description in the future.

Consuming some secondary metabolites can have severe consequences. Alkaloids can
block ion channels, inhibit enzymes , or interfere with neurotransmission, producing
hallucinations , loss of coordination, convulsions, vomiting, and death. Some
phenolics interfere with digestion, slow growth, block enzyme activity and cell division,
or just taste awful.

Most herbivores and plant pathogens possess mechanisms that ameliorate the impacts
of plant metabolites, leading to evolutionary associations between particular groups of
pests and plants. Some herbivores (for example, the monarch butterfly) can store
(sequester) plant toxins and gain protection against their enemies. Secondary
metabolites may also inhibit the growth of competitor plants (allelopathy). Pigments
(such as terpenoid carotenes, phenolics, and flavonoids) color flowers and, together with
terpene and phenolic odors, attract pollinators.
Secondary chemicals are important in plant use by humans. Most pharmaceuticals are
based on plant chemical structures, and secondary metabolites are widely used for
recreation and stimulation (the alkaloids nicotine and cocaine; the terpene cannabinol).
The study of such plant use is called ethnopharmacology. Psychoactive plant chemicals
are central to some religions, and flavors of secondary compounds shape our food
preferences. The characteristic flavors and aroma of cabbage and relatives are caused by




Class                   Example            Example             Some Effects and Uses
                        Compounds          Sources


NITROGEN-
CONTAINING


Alkaloids               nicotine cocaine   tobacco coca plant interfere with
                        theobromine        chocolate (cocao)   neurotransmission, block
Class                  Example           Example              Some Effects and Uses
                       Compounds         Sources


                                                              enzyme action


NITROGEN-AND
SULFUR-
CONTAINING


Glucosinolates         sinigrin          cabbage, relatives


TERPENOIDS


Monoterpenes           menthol linalool mint and relatives, interfere with
                                         many plants          neurotransmission, block ion
                                                              transport, anesthetic


Sesquiterpenes         parthenolid       Parthenium and       contact dermatitis
                                         relatives (
                                         Asteraceae )


Diterpenes             gossypol          cotton               block phosphorylation; toxic


Triterpenes, cardiac   digitogenin       Digitalis (foxglove) stimulate heart muscle, alter
glycosides                                                    ion transport


Tetraterpenoids        carotene          many plants          antioxidant; orange coloring


Terpene polymers       rubber            Hevea (rubber)       gum up insects; airplane tires
                                         trees, dandelion


Sterols                spinasterol       spinach              interfere with animal hormone
                                                              action


PHENOLICS
Class                    Example              Example              Some Effects and Uses
                         Compounds            Sources


Phenolic acids           caffeic,             all plants           cause oxidative damage,
                         chlorogenic                               browning in fruits and wine


Coumarins                umbelliferone        carrots, parsnip     cross-link DNA, block cell
                                                                   division


Lignans                  podophyllin          mayapple poison      cathartic, vomiting, allergic
                         urushiol             ivy                  dermatitis


Flavonoids               anthocyanin,         almost all plants    flower, leaf color; inhibit
                         catechin                                  enzymes, anti- and pro-
                                                                   oxidants, estrogenic


Tannins                  gallotannin,         oak, hemlock trees, bind to proteins, enzymes,
                         condensed            birdsfoot trefoil,   block digestion, antioxidants
                         tannin               legumes


Lignin                   lignin               all land plants      structure, toughness, fiber



nitrogen-and sulfur-containing chemicals, glucosinolates, which protect these plants
from many enemies. The astringency of wine and chocolate derives from tannins. The
use of spices and other seasonings developed from their combined uses as preservatives
(since they are antibiotic) and flavorings.

SEE ALSO Flowers ; Herbivory and Plant Defenses ; Metabolism,           Cellular ; Poisons

Jack Schultz

Bibliography
Agosta, William. Bombardier Beetles and Fever Trees: A Close-up Look at Chemical
Warfare and Signals in Animals and Plants. Reading, MA: Addison-Wesley, 1996.

Bidlack, Wayne R. Phytochemicals as Bioactive Agents. Lancaster, PA: Technomic
Publishers, 2000.

Karban, Richard, and Ian T. Baldwin. Induced Responses to Herbivory. Chicago:
University of Chicago Press, 1997.

Rosenthal, Gerald A., and May R. Berenbaum. Herbivores, Their Interactions with
Secondary Plant Metabolites. San Diego, CA: Academic Press, 1991.




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User Contributions:



                                             1

aarcee varte




Mar 4, 2008 @ 11:23 pm


please explain how 2 extract secondary metabolites which is not secreted out from plants
and remain inside the plants only

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Cellulose

From Wikipedia, the free encyclopedia
Jump to: navigation, search


                        Cellulose[1]




                          Identifiers


  CAS number                  9004-34-6


  UNII                        SMD1X3XO9M


  EC-number                   232-674-9


  ChEMBL                      CHEMBL1201676


                          Properties


  Molecular formula           (C6H10O5)n


  Appearance                  white powder


  Density                     1.5 g/cm3


  Melting point               decomp.

  Solubility in water         none
Hazards


  EU Index                      not listed




  NFPA 704                                      1
                                                1
                                                0
                       Related compounds


  Related compounds             Starch


                        (verify) (what is:   / ?)
   Except where noted otherwise, data are given for materials
             in their standard state (at 25 °C, 100 kPa)


                        Infobox references

Cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a
linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units.[2][3]

Cellulose is the structural component of the primary cell wall of green plants, many forms of
algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the
most common organic compound on Earth. About 33% of all plant matter is cellulose (the
cellulose content of cotton fiber is 90%, that of wood is 40–50% and that of dried hemp is
approximately 75%).[4][5][6]

For industrial use, cellulose today is mainly obtained from wood pulp and cotton. Cellulose is
mainly used to produce paperboard and paper; to a smaller extent it is converted into a wide
variety of derivative products such as cellophane and rayon. Converting cellulose from energy
crops into biofuels such as cellulosic ethanol is under investigation as an alternative fuel source.

Some animals, particularly ruminants and termites, can digest cellulose with the help of
symbiotic micro-organisms that live in their guts. Humans can digest cellulose to some
extent,[7][8] however it mainly acts as a hydrophilic bulking agent for feces and is often referred
to as "dietary fiber".

Contents

        1 History
        2 Products
            o 2.1 Cellulose source and energy crops
        3 Structure and properties
        4 Assaying a cellulose-containing material
        5 Biosynthesis
        6 Breakdown (cellulolysis)
        7 Hemicellulose
        8 Derivatives
        9 References
        10 External links


[edit] History

Cellulose was discovered in 1838 by the French chemist Anselme Payen, who isolated it from
plant matter and determined its chemical formula.[2][9][10] Cellulose was used to produce the first
successful thermoplastic polymer, celluloid, by Hyatt Manufacturing Company in 1870.
Hermann Staudinger determined the polymer structure of cellulose in 1920. The compound was
first chemically synthesized (without the use of any biologically derived enzymes) in 1992, by
Kobayashi and Shoda.[11]




Cellulose in a plant cell.

[edit] Products
Cotton fibres represent the purest natural form of cellulose, containing more than 90% of this
carbohydrate.

See also: dissolving pulp and pulp (paper)

The kraft process is used to separate cellulose from lignin, another major component of plant
matter. Cellulose is the major constituent of paper, paperboard, and card stock and of textiles
made from cotton, linen, and other plant fibers.

Cellulose can be converted into cellophane, a thin transparent film, and into rayon, an important
fiber that has been used for textiles since the beginning of the 20th century. Both cellophane and
rayon are known as "regenerated cellulose fibers"; they are identical to cellulose in chemical
structure and are usually made from dissolving pulp via viscose. A more recent and
environmentally friendly method to produce a form of rayon is the Lyocell process. Cellulose is
the raw material in the manufacture of nitrocellulose (cellulose nitrate) which is used in
smokeless gunpowder and as the base material for celluloid used for photographic and movie
films until the mid 1930s.

Cellulose is used to make water-soluble adhesives and binders such as methyl cellulose and
carboxymethyl cellulose which are used in wallpaper paste. Microcrystalline cellulose (E460i)
and powdered cellulose (E460ii) are used as inactive fillers in tablets[12] and as thickeners and
stabilizers in processed foods. Cellulose powder is for example used in Kraft's Parmesan cheese
to prevent caking inside the tube.

Cellulose is used in the laboratory as the stationary phase for thin layer chromatography.
Cellulose fibers are also used in liquid filtration, sometimes in combination with diatomaceous
earth or other filtration media, to create a filter bed of inert material. Cellulose is further used to
make hydrophilic and highly absorbent sponges.

Cellulose insulation made from recycled paper is becoming popular as an environmentally
preferable material for building insulation. It can be treated with boric acid as a fire retardant.

Cellulose consists of crystalline and amorphous regions. By treating it with strong acid, the
amorphous regions can be broken up, thereby producing nanocrystalline cellulose, a novel
material with many desirable properties.[13] Recently, nanocrystalline cellulose was used as the
filler phase in bio-based polymer matrices to produce nanocomposites with superior thermal and
mechanical properties. [14]

[edit] Cellulose source and energy crops

Main article: Energy crop

The major combustible component of non-food energy crops is cellulose, with lignin second.
Non-food energy crops are more efficient than edible energy crops (which have a large starch
component), but still compete with food crops for agricultural land and water resources.[15]
Typical non-food energy crops include industrial hemp (though outlawed in some countries),
switchgrass, Miscanthus, Salix (willow), and Populus (poplar) species.

Some bacteria can convert cellulose into ethanol which can then be used as a fuel; see cellulosic
ethanol.




A strand of cellulose (conformation Iα), showing the hydrogen bonds (dashed) within and between
cellulose molecules.

[edit] Structure and properties

Cellulose has no taste, is odorless, is hydrophilic with the contact angle of 20–30,[16] is insoluble
in water and most organic solvents, is chiral and is biodegradable. It can be broken down
chemically into its glucose units by treating it with concentrated acids at high temperature.

Cellulose is derived from D-glucose units, which condense through β(1→4)-glycosidic bonds.
This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch, glycogen,
and other carbohydrates. Cellulose is a straight chain polymer: unlike starch, no coiling or
branching occurs, and the molecule adopts an extended and rather stiff rod-like conformation,
aided by the equatorial conformation of the glucose residues. The multiple hydroxyl groups on
the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a
neighbor chain, holding the chains firmly together side-by-side and forming microfibrils with
high tensile strength. This strength is important in cell walls, where the microfibrils are meshed
into a carbohydrate matrix, conferring rigidity to plant cells.




A triple strand of cellulose showing the hydrogen bonds (cyan lines) between glucose strands

Compared to starch, cellulose is also much more crystalline. Whereas starch undergoes a
crystalline to amorphous transition when heated beyond 60–70 °C in water (as in cooking),
cellulose requires a temperature of 320 °C and pressure of 25 MPa to become amorphous in
water.[17]

Several different crystalline structures of cellulose are known, corresponding to the location of
hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures Iα
and Iβ. Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants
consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II. The conversion of
cellulose I to cellulose II is irreversible, suggesting that cellulose I is metastable and cellulose II
is stable. With various chemical treatments it is possible to produce the structures cellulose III
and cellulose IV.[18]

Many properties of cellulose depend on its chain length or degree of polymerization, the number
of glucose units that make up one polymer molecule. Cellulose from wood pulp has typical chain
lengths between 300 and 1700 units; cotton and other plant fibers as well as bacterial cellulose
have chain lengths ranging from 800 to 10,000 units.[11] Molecules with very small chain length
resulting from the breakdown of cellulose are known as cellodextrins; in contrast to long-chain
cellulose, cellodextrins are typically soluble in water and organic solvents.

Plant-derived cellulose is usually found in a mixture with hemicellulose, lignin, pectin and other
substances, while microbial cellulose is quite pure, has a much higher water content, and consists
of long chains.

Cellulose is soluble in cupriethylenediamine (CED), cadmiumethylenediamine (Cadoxen), N-
methylmorpholine N-oxide and lithium chloride / dimethylformamide.[19] This is used in the
production of regenerated celluloses (such as viscose and cellophane) from dissolving pulp.

[edit] Assaying a cellulose-containing material

Given a cellulose-containing material, the carbohydrate portion that does not dissolve in a 17.5%
solution of sodium hydroxide at 20 °C is α cellulose, which is true cellulose. Acidification of the
extract precipitates β cellulose. The portion that dissolves in base but does not precipitate with
acid is γ cellulose.
Cellulose can be assayed using a method described by Updegraff in 1969, where the fiber is
dissolved in acetic and nitric acid to remove lignin, hemicellulose, and xylosans. The resulting
cellulose is allowed to react with anthrone in sulfuric acid. The resulting coloured compound is
assayed spectrophotometrically at a wavelength of approximately 635 nm.

In addition, cellulose is represented by the difference between acid detergent fiber (ADF) and
acid detergent lignin (ADL).

[edit] Biosynthesis




Location and arrangement of cellulose microfibrils in the plant cell wall

In vascular plants cellulose is synthesized at the plasma membrane by rosette terminal complexes
(RTCs). The RTCs are hexameric protein structures, approximately 25 nm in diameter, that
contain the cellulose synthase enzymes that synthesise the individual cellulose chains.[20] Each
RTC floats in the cell's plasma membrane and "spins" a microfibril into the cell wall.

RTCs contain at least three different cellulose synthases, encoded by CesA genes, in an unknown
stoichiometry.[21] Separate sets of CesA genes are involved in primary and secondary cell wall
biosynthesis.

Cellulose synthesis requires chain initiation and elongation, and the two processes are separate.
CesA glucosyltransferase initiates cellulose polymerization using a steroid primer, sitosterol-
beta-glucoside, and UDP-glucose.[22] Cellulose synthase utilizes UDP-D-glucose precursors to
elongate the growing cellulose chain. A cellulase may function to cleave the primer from the
mature chain.

Cellulose is also synthesised by animals, particularly in the tests of ascidians (where the cellulose
was historically termed "tunicine") although it is also a minor component of mammalian
connective tissue.[23]

[edit] Breakdown (cellulolysis)

Cellulolysis is the process of breaking down cellulose into smaller polysaccharides called
cellodextrins or completely into glucose units; this is a hydrolysis reaction. Because cellulose
molecules bind strongly to each other, cellulolysis is relatively difficult compared to the
breakdown of other polysaccharides.[24] Processes do exist however for the breakdown of
cellulose such as the Lyocell process [25] which uses a combination of heated water and acetone
to break down the cellulose strands.

Most mammals have only very limited ability to digest dietary fibres such as cellulose. Some
ruminants like cows and sheep contain certain symbiotic anaerobic bacteria (like Cellulomonas)
in the flora of the rumen, and these bacteria produce enzymes called cellulases that help the
microorganism to break down cellulose; the breakdown products are then used by the bacteria
for proliferation. The bacterial mass is later digested by the ruminant in its digestive system
(stomach and small intestine). Similarly, lower termites contain in their hindguts certain
flagellate protozoa which produce such enzymes; higher termites contain bacteria for the job.
Some termites may also produce cellulase of their own.[26] Fungi, which in nature are responsible
for recycling of nutrients, are also able to break down cellulose.

The enzymes utilized to cleave the glycosidic linkage in cellulose are glycoside hydrolases
including endo-acting cellulases and exo-acting glucosidases. Such enzymes are usually secreted
as part of multienzyme complexes that may include dockerins and carbohydrate-binding
modules.[27]

[edit] Hemicellulose

Main article: Hemicellulose

Hemicellulose is a polysaccharide related to cellulose that comprises about 20% of the biomass
of most plants. In contrast to cellulose, hemicellulose is derived from several sugars in addition
to glucose, especially xylose but also including mannose, galactose, rhamnose, and arabinose.
Hemicellulose consists of shorter chains – around 200 sugar units. Furthermore, hemicellulose is
branched, whereas cellulose is unbranched.

[edit] Derivatives

The hydroxyl groups (-OH) of cellulose can be partially or fully reacted with various reagents to
afford derivatives with useful properties like mainly cellulose esters and cellulose ethers (-OR).
In principle, though not always in current industrial practice, cellulosic polymers are renewable
resources.

Ester derivatives include:

 Cellulose
              Reagent           Example                   Reagent                 Group R
   ester

Organic      Organic                            Acetic acid and acetic
                         Cellulose acetate                                H or -(C=O)CH3
esters       acids                              anhydride

                                                Acetic acid and acetic
                         Cellulose triacetate                             -(C=O)CH3
                                                anhydride
Cellulose propionate      Propanoic acid                 H or -(C=O)CH2CH3

                          Cellulose acetate         Acetic acid and propanoic      H or -(C=O)CH3 or -
                          propionate                acid                           (C=O)CH2CH3

                          Cellulose acetate                                        H or -(C=O)CH3 or -
                                                    Acetic acid and butyric acid
                          butyrate                                                 (C=O)CH2CH2CH3

Inorganic    Inorganic    Nitrocellulose            Nitric acid or another
                                                                                   H or -NO2
esters       acids        (cellulose nitrate)       powerful nitrating agent

                                                    Sulfuric acid or another
                          Cellulose sulfate                                        H or -SO3H
                                                    powerful sulfuring agent


The cellulose acetate and cellulose triacetate are film- and fiber-forming materials that find a
variety of uses. The nitrocellulose was initially used as an explosive and was an early film
forming material. With camphor, nitrocellulose gives celluloid.

Ether derivatives include:

                                                                           Water                  E
 Cellulose                                                    Group R = H
                Reagent         Example           Reagent                 solubilit Application numbe
  ethers                                                          or
                                                                             y                    r

                                                                            Cold
             Halogenoalkan Methylcellulo Chloromethan
Alkyl                                                 -CH3                  water                    E461
             es            se            e
                                                                            soluble

                                                                                     A
                                                                                     commercial
                                                                                     thermoplasti
                                                                                     c used in
                                                                            Water
                                                                                     coatings,
                             Ethylcellulose Chloroethane -CH2CH3            insolubl                E462
                                                                                     inks, binders,
                                                                            e
                                                                                     and
                                                                                     controlled-
                                                                                     release drug
                                                                                     tablets

                             Ethyl methyl       Chloromethan -CH3 or -                               E465
                             cellulose          e and        CH2CH3
chloroethane

                                                                               Cold/ho Gelling and
Hydroxyalk                    Hydroxyethyl Ethylene
           Epoxides                                             -CH2CH2OH      t water thickening
yl                            cellulose    oxide
                                                                               soluble agent

                              Hydroxypropy                      -          Cold
                                           Propylene
                              l cellulose                       CH2CH(OH)C water                         E463
                                           oxide
                              (HPC)                             H3         soluble

                                           Chloromethan
                              Hydroxyethyl                                     Cold    Production of
                                           e and        -CH3 or -
                              methyl                                           water cellulose
                                           ethylene     CH2CH2OH
                              cellulose                                        soluble films
                                           oxide

                                                                           Viscosity
                              Hydroxypropy Chloromethan                    modifier,
                                                        -CH3 or -  Cold
                              l methyl     e and                           gelling,
                                                        CH2CH(OH)C water               E464
                              cellulose    propylene                       foaming and
                                                        H3         soluble
                              (HPMC)       oxide                           binding
                                                                           agent

                              Ethyl        Chloroethane
                                                        -CH2CH3 or—
                              hydroxyethyl and ethylene                                                  E467
                                                        CH2CH2OH
                              cellulose    oxide

                                                                                       Often used
                                                                                       as its sodium
                            Carboxymethy                                       Cold/Ho
Carboxyalk Halogenated                   Chloroacetic                                  salt, sodium
                            l cellulose                         -CH2COOH       t water               E466
yl         carboxylic acids              acid                                          carboxymeth
                            (CMC)                                              soluble
                                                                                       yl cellulose
                                                                                       (NaCMC)


The sodium carboxymethyl cellulose can be cross-linked to give the croscarmellose sodium
(E468) for use as a disintegrant in pharmaceutical formulations.

[edit] References

   1.   ^ Nishiyama, Yoshiharu; Langan, Paul; Chanzy, Henri (2002). "Crystal Structure and Hydrogen-Bonding
        System in Cellulose Iβ from Synchrotron X-ray and Neutron Fiber Diffraction". J. Am. Chem. Soc 124 (31):
        9074–82. doi:10.1021/ja0257319. PMID 12149011..
          ab
   2.   ^ Crawford, R. L. (1981). Lignin biodegradation and transformation. New York: John Wiley and Sons.
        ISBN 0-471-05743-6.
3.    ^ Updegraff DM (1969). "Semimicro determination of cellulose in biological materials". Analytical
      Biochemistry 32 (3): 420–424. doi:10.1016/S0003-2697(69)80009-6. PMID 5361396.
4.    ^ Cellulose. (2008). In Encyclopædia Britannica. Retrieved January 11, 2008, from Encyclopædia Britannica
      Online.
5.    ^ Chemical Composition of Wood
6.    ^ G. Buschle-Diller, C. Fanter, F. Loth (April 1999). "Structural changes in hemp fibers as a result of
      enzymatic hydrolysis with mixed enzyme systems". Textile Research Journal 69 (4): 244-251.
      http://www.globalhemp.com/1999/04/structural-changes-in-hemp-fibers-as-a-result-of-enzymatic-
      hydrolysis-with-mixed-enzyme-systems.html.
7.    ^ Slavin, JL; Brauer, PM; Marlett, JA (1981). "Neutral detergent fiber, hemicellulose and cellulose
      digestibility in human subjects.". The Journal of Nutrition 111 (2): 287–97. PMID 6257867.
8.    ^ Joshi, S; Agte, V (1995). "Digestibility of dietary fiber components in vegetarian men.". Plant foods for
      human nutrition (Dordrecht, Netherlands) 48 (1): 39–44. doi:10.1007/BF01089198. PMID 8719737.
9.    ^ A. Payen (1838) "Mémoire sur la composition du tissu propre des plantes et du ligneux" (Memoir on the
      composition of the tissue of plants and of woody [material]), Comptes rendus, vol. 7, pages 1052-1056.
      Payen added appendices to this paper on December 24, 1838 (see: Comptes rendus, vol. 8, page 169
      (1839)) and on February 4, 1839 (see: Comptes rendus, vol. 9, page 149 (1839)). A committee of the
      French Academy of Sciences reviewed Payen's findings in : Jean-Baptiste Dumas (1839) "Rapport sur un
      mémoire de M. Payen, relatif à la composition de la matière ligneuse" (Report on a memoir of Mr. Payen,
      regarding the composition of woody matter), Comptes rendus, vol. 8, pages 51-53. In this report, the word
      "cellulose" is coined and author points out the similarity between the empirical formula of cellulose and
      that of "dextrine" (starch). The above articles are reprinted in: Brongniart and Guillemin, eds., Annales des
      sciences naturelles ..., 2nd series, vol. 11 (Paris, France: Crochard et Cie., 1839), pages 21-31.
10.   ^ Young, Raymond (1986). Cellulose structure modification and hydrolysis. New York: Wiley. ISBN 0-471-
      82761-4.
        ab
11.   ^ Klemm, Dieter; Brigitte Heublein, Hans-Peter Fink, Andreas Bohn (2005). "Cellulose: Fascinating
      Biopolymer and Sustainable Raw Material". ChemInform 36 (36). doi:10.1002/chin.200536238.
12.   ^ Weiner, Myra L.; Lois A. Kotkoskie (2000). Excipient Toxicity and Safety. New York ; Dekker. p. 210.
      ISBN 0-8247-8210-0.
13.   ^ Peng, B. L., Dhar, N., Liu, H. L. and Tam, K. C. (2011). "Chemistry and applications of nanocrystalline
      cellulose and its derivatives: A nanotechnology perspective.". The Canadian Journal of Chemical
      Engineering 89 (5): 1191–1206.
      http://www.arboranano.ca/pdfs/Chemistry%20and%20applications%20of%20nanocrystalline%20cellulos
      e%20and%20its%20derivatives%20A%20nanotechnology%20perspective-2011.pdf.
14.   ^ Lawrence Pranger and Rina Tannenbaum "Biobased nanocomposites prepared by in situ polymerization
      of furfuryl alcohol with cellulose whiskers or montmorillonite clay" Macromolecules 41 (2008) 8682.
      http://dx.doi.org/10.1021/ma8020213
15.   ^ Holt-Gimenez, Eric 2007. Biofuels: Myths of the Agrofuels Transition. Backgrounder. Institute for Food
      and Development Policy, Oakland, CA. 13:2
16.   ^ Charles A. Bishop, ed. (2007). Vacuum deposition onto webs, films, and foils, Volume 0, Issue 8155.
      p. 165. ISBN 0-8155-1535-9. http://books.google.com/books?id=vP9E3z7o6iIC&pg=PA165.
17.   ^ Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki (2006). "Cooking cellulose in hot and compressed water".
      Chemical Communications (31): 3293. doi:10.1039/b605812d.
18.   ^ Structure and morphology of cellulose by Serge Pérez and William Mackie, CERMAV-CNRS, 2001.
      Chapter IV.
19.   ^ Stenius, Per (2000). "1". Forest Products Chemistry. Papermaking Science and Technology. 3. Finland:
      Fapet OY. p. 35. ISBN 952-5216-03-9.
20.   ^ Kimura, S; Laosinchai, W; Itoh, T; Cui, X; Linder, CR; Brown Jr, RM (1999). "Immunogold labeling of
      rosette terminal cellulose-synthesizing complexes in the vascular plant vigna angularis". The Plant cell 11
      (11): 2075–86. doi:10.2307/3871010. JSTOR 3871010. PMC 144118. PMID 10559435.
      //www.ncbi.nlm.nih.gov/pmc/articles/PMC144118/.
21.   ^ Taylor, N. G. (2003). "Interactions among three distinct CesA proteins essential for cellulose synthesis".
      Proceedings of the National Academy of Sciences 100 (3): 1450. doi:10.1073/pnas.0337628100.
22. ^ Peng, L; Kawagoe, Y; Hogan, P; Delmer, D (2002). "Sitosterol-beta-glucoside as primer for cellulose
       synthesis in plants". Science 295 (5552): 147–50. doi:10.1126/science.1064281. PMID 11778054.
   23. ^ Endean, The Test of the Ascidian, Phallusia mammillata, Quarterly Journal of Microscopical Science, Vol.
       102, part 1, pp. 107-117, 1961.
   24. ^ David G. Barkalow, Roy L. Whistler, "Cellulose", in AccessScience, McGraw-Hill, doi:10.1036/1097-
       8542.118200. Retrieved 11 January 2008.
   25. ^ H.Lyocell, "Cellulose" Issue 41, pp 419
   26. ^ Tokuda, G; Watanabe, H (22 June 2007). "Hidden cellulases in termites: revision of an old hypothesis".
       Biology Letters 3 (3): 336–339. doi:10.1098/rsbl.2007.0073. PMC 2464699. PMID 17374589.
       http://rsbl.royalsocietypublishing.org/content/3/3/336.long
   27. ^ Brás, Natércia; N. M. F. S. A. Cerqueira, P. A. Fernandes, M. J. Ramos (2008). "Carbohydrate Binding
       Modules from family 11: Understanding the binding mode of polysaccharides". International Journal of
       Quantum Chemistry 108 (11): 2030–2040. doi:10.1002/qua.21755.

[edit] External links

       Structure and morphology of cellulose by Serge Pérez and William Mackie, CERMAV-CNRS
       Cellulose, by Martin Chaplin, London South Bank University
       Clear description of a cellulose assay method at the Cotton Fiber Biosciences unit of the USDA.
       Cellulose films could provide flapping wings and cheap artificial muscles for robots -
       TechnologyReview.com
       Using cellulase enzymes in the bioethanol process
       A list of cellulolytic bacteria


                                                           v
                                                            t
                                                           e

                                        Types of carbohydrates


                                 Aldose
                                 Furanose
            General
                                 Ketose
                                 Pyranose



                                 Anomer
          Geometry               Cyclohexane conformation
                                 Mutarotation
Aldodiose
                    Dioses
                                o   Glycolaldehyde



                             Aldotriose
                                o   Glyceraldehyde
                   Trioses
                             Ketotriose
                                o   Dihydroxyacetone



                             Aldotetroses
                                o   Erythrose
                  Tetroses      o   Threose
                             Ketotetrose
                                o   Erythrulose

Monosaccharides
                             Aldopentose
                                o   Arabinose
                                o   Lyxose
                                o   Ribose
                                o   Xylose
                  Pentoses
                             Deoxy sugar
                                o   Deoxyribose
                             Ketopentose
                                o   Ribulose
                                o   Xylulose



                             Aldohexose
                  Hexoses
                                o   Allose
                                o   Altrose
o     Galactose
                                o     Glucose
                                o     Gulose
                                o     Idose
                                o     Mannose
                                o     Talose
                             Deoxy sugar
                                o     Fucose
                                o     Fuculose
                                o     Rhamnose
                             Ketohexose
                                o     Fructose
                                o     Psicose
                                o     Sorbose
                                o     Tagatose



                             Ketoheptose
           Heptoses             o     Mannoheptulose
                                o     Sedoheptulose



                             Octose
                >7           Nonose
                                o     Neuraminic acid



                                      Cellobiose

Multiple     Disaccharides            Lactose
                                      Maltose
                                      Sucrose
Trehalose
                   Turanose



                   Maltotriose
  Trisaccharides   Melezitose
                   Raffinose



Tetrasaccharides   Stachyose



                   Acarbose
                   Fructooligosaccharide (FOS)

          Other    Galactooligosaccharide (GOS)
oligosaccharides   Isomaltooligosaccharide (IMO)
                   Maltodextrin
                   Mannan-oligosaccharides (MOS)



                   Beta-glucan
                       o    Lentinan
                       o    Sizofiran
                       o    Zymosan
                   Cellulose

Polysaccharides    Chitin
                   Dextrin / Dextran
                   Fructose / Fructan
                       o    Inulin
                   Galactose / Galactan
                   Glucose / Glucan
                       o    Glycogen
Levan beta 2→6
                                             Mannan
                                             Starch
                                                     o   Amylopectin
                                                     o   Amylose



                  biochemical families: carbohydrates
                                 o     alcohols
                            o        glycoproteins
                                o     glycosides
                                        lipids
                             o       eicosanoids
                   o      fatty acids / intermediates
                            o       phospholipids
                            o        sphingolipids
                                 o     steroids
                                     nucleic acids
                  o      constituents / intermediates
                                       proteins
                   o     amino acids / intermediates
                         tetrapyrroles / intermediates

                                                 v
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         Issues           Environmental impact of paper
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                                          Category   Commons

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Introduction



Some useful constants in thermodynamics:

        1 eV = 9.6522E4 J/mol
        k Boltzmann's constant = 1.38E-23 J/K
        volume: 1 cm3 = 0.1 kJ/kbar = 0.1 J/bar
        mole: 1 mole of a substance contains Avogadro's number (N = 6.02E23) of molecules.
        Abbreviated as 'mol'.
        atomic weights are based around the definition that 12C is exactly 12 g/mol
        R gas constant = Nk = 8.314 J mol-1 K-1

Units of Temperature: Degrees Celsius and Kelvin

The Celsius scale is based on defining 0 °C as the freezing point of water and 100°C as the boiling point.

The Kelvin scale is based on defining 0 K, "absolute zero," as the temperature at zero pressure
where the volumes of all gases is zero--this turns out to be -273.15 °C. This definition means that
the freezing temperature of water is 273.15 K. All thermodynamic calculations are done in
Kelvin!

kilo and kelvin: write k for 1000's and K for kelvin. Never write °K.

Units of Energy: Joules and Calories

Joules and calories and kilocalories: A calorie is defined as the amount of energy required to raise the
temperature of 1 g of water from 14.5 to 15.5°C at 1 atm.
4.184 J = 1 cal; all food 'calories' are really kcal.
Many times it is easiest to solve equations or problems by conducting "dimensional analysis,"
which just means using the same units throughout an equation, seeing that both sides of an
equation contain balanced units, and that the answer is cast in terms of units that you want. As an
example, consider the difference between temperature (units of K) and heat (units of J). Two
bodies may have the same temperature, but contain different amounts of heat; likewise, two
bodies may contain the same heat, but be at different temperatures. The quantity that links these
two variables must have units of J/K or K/J. In fact, the heat capacity C describes the amount of
heat dQ involved in changing one mole of a substance by a given temperature increment dT:

        dQ = CdT

The heat capacity C is then

        C = dQ/dT

and must have units of J K-1 mol-1. (The specific heat is essentially the same number, but is expressed per
gram rather than per mole.)
Don't forget significant digits. 1*2=2; 1.1*2=2; 1.1*2.0=2.2; 1.0*2.0=2.0

Why Thermodynamics?

Think about some everyday experiences you have with chemical reactions.
Your ability to melt and refreeze ice shows you that H2O has two phases and that the reaction
transforming one to the other is reversible--apparently the crystallization of ice requires removing some
heat.
Frying an egg is an example of an irreversible reaction.
If you dissolve halite in water you can tell that the NaCl is still present in some form by tasting the water.
Why does the NaCl dissolve? Does it give off heat? Does it require energy?
How is it that diamond, a high-pressure form of C, can coexist with the low pressure form, graphite, at
Earth's surface? Do diamond and graphite both have the same energy? If you burn graphite and
diamond, which gives you more energy?
When dynamite explodes, why does it change into a rapidly expanding gas, which provides the energy
release, plus a few solids?
Chemical thermodynamics provides us with a means of answering these questions and more.

A Few Definitions

A system is any part of the universe we choose to consider.
Matter and energy can flow in or out of an open system but only energy can be added to or subtracted
from a closed system. An isolated system is one in which matter and energy are conserved.
A phase is a homogeneous body of matter. The components of a system are defined by a set of
chemical formula used to describe the system.
The phase rule:
F + P = C + 2.

Extensive parameters are proportional to mass (e.g., V, mass, energy).
Intensive parameters are independent of mass (e.g., P, T); these are the "degrees of freedom" F
contained in the phase rule.

Thermodynamics: Power and Limitations

Thermodynamics allows you to predict how chemical systems should behave from a supra-atomic
"black-box" level--it says nothing about how chemical systems will behave. Thermodynamics also
pertains to the state of a system, and says nothing about the path taken by the system in changing from
one state to another.

Chemical Reactions and Equations

How to write chemical reactions; stoichiometry.
Mass and charge balance: e.g.,

        2Fe3+ + 3H2O = Fe2O3 + 6H+

Reaction-Produced Change in Mass, Density, Volume

The change in volume             rV   of a reaction is the volume V of the products minus the volume of the
reactants:

             rV   = Vproducts - Vreactants

Thus, if the products are smaller than the reactants,            rV   < 0.
In a generalized reaction such as

        aA + bB ... = cC + dD...

             rV   = cVC + dVD - aVA - bVB

This sort of additive relationship is true for other state variables and is usually stated as



             r           i   i


where    i   are the stoichiometric coefficients, positive for products and negative for reactants.

What Actually Drives Reactions? Is it Energy? Can We Just Calculate or Measure the Energy
Difference of Reactants and Products and Know Which Way the Reaction Will Go?
For many years people felt that chemical reactions occurred because the reactants had some kind of
energy to give up (i.e., use to do work)--and that therefore the energy of the products would be less
than the energy of the reactants. However, we all know that when ice melts it consumes rather than
releases heat, so there must be more to the story behind why chemical reactions occur.

Le Chatelier's Principle

"If a change is made to a system, the system will respond so as to absorb the force causing the change."

Equilibrium

A mechanical analogy for chemical change is that of a ball rolling down a slope with multiple valleys; we
explain the ball's behavior by saying that mechanical systems have a tendency to reduce their potential
energy.
At equilibrium none of the properties of a system change with time. A system at equilibrium returns to
equilibrium if disturbed.
"Stable" describes a system or phase in its lowest energy state.
"Metastable" describes a system or phase in any other energy state.




The figure above shows the mechanical analogy for H2O at -5°C and + 5°C and 1 atm. Left: at -5°C, solid
H2O has the lowest possible energy state. Right: at +5°C, liquid H2O has the lowest possible energy state.
When solid H2O is actually present at +5°C, the difference between the free energy of solid H2O and
liquid H2O is available to drive the reaction to form the stable solid H2O phase, and the reaction will go
to completion if kinetically possible.
Energy: How Do We Calculate and Measure Energy and How Can We Use this Knowledge to
Predict Reaction Behavior?

Thermodynamics works equally well to describe any kind of work or energy: magnetic, potential, kinetic,
etc. For geological systems we typically talk about pressure-volume work, which, because mechanical
work is F x, you can imagine might be

       P    V

or

       V    P

Because we noted that    rV   < 0 if the products are smaller than the reactants, we choose to write the P-
V work term as

       -P   V

so that a decrease in volume - V is seen as positive work or that an increase in volume + V results in
a decrease in crystal energy.
The absolute energy of a body can be calculated from Einstein's equation U=mc2, but the presence of
the c2 term means that the energy of any system is quite large and that measuring this energy is
impractical. It is more practical to measure differences in energy U, and we always discuss or measure
differences relative to some arbitrary standard state. Analogous to this might be if someone in Namibia
asked you to measure the elevation of the crests of waves at Campus Point--without agreement on
some kind of standard, you wouldn't be able to do much more than measure the heights of individual
waves. If however, you could both agree on an equivalent "sea level" at both localities, you could then
compare the absolute elevations of the wave crests.

A typical thermodynamic standard state is normal laboratory conditions: 25°C (298.15 K) and 1
atm (often called STP for standard temperature and pressure).

The internal energy U of a mineral is the sum of the potential energy stored in the interatomic
bonds and the kinetic energy of the atomic vibrations. Thus, you might expect that weakly
bonded minerals have relatively low potential energy and thus low internal energy, and when a
mineral is cold such that its atomic vibrations are slow it will have low kinetic energy and thus
low internal energy. Internal energies are always defined relative to some non-zero standard
state, so we typically talk about changes in internal energy dU.

                              An Aside on Differences and Differentials

What's the difference among         , d , and        ?
 is used to indicate any kind of difference.
d is used to indicate a differential.
   is used to indicate a partial differential. For example, the partial differential, with respect to y, of
f(x,y) = x3y4
is
= 4x3y3



First Law of Thermodynamics

Adding heat Q to a crystal increases its internal energy U:

        dU     dQ

( indicates 'proportional') but if the crystal is allowed to expand, some of the added energy will be
consumed by expansion dV, so the total energy of the crystal is reduced:

        dU = dQ - PdV

This is effectively the First Law of Thermo: that total energy (heat + P-V work) is conserved.

Heat Capacity

Heat capacity C describes the amount of heat required to change the temperature of a substance:



        C=

By definition, the heat capacity of water at 15°C is 1 cal K-1 g-1 or 18 cal K-1 mol-1 (i.e., the heat required
to heat 1 gram of water from 14.5 to 15.5°C is 1 calorie).
Heat capacities of solids approach zero as absolute zero is approached:


               C=0

The heat capacity is written with a subscript P or V depending on whether it obtains for constant
pressure CP or constant volume CV.

As an aside,

                        2
        CP = CV + TV     /
where and are the expansivity and compressibility--for solids the difference between CP and CV is
minimal and can be ignored as a first approximation. For gases, CP = CV + R, and is quite significant.
Heat capacities are measured by calorimetry and often fit by a function of the form:

        CP = a + bT + cT-2 + dT-0.5

but there are other expansions for the heat capacity involving more or fewer terms.
Below are some examples of heat capacities of minerals. Note how silicates have a nearly constant heat
capacity of ~1 J K-1 g-1 above 400K.
Enthalpy

We have already talked about the familiar concept of heat as energy.
Let's define another measure of energy called enthalpy H--a kind of measure of the thermal energy of a
crystal. As we will see below,
dH = dQ + VdP

Recall that we interpreted

        dU = dQ - PdV

to mean that the internal energy change is the heat change minus the energy lost to relaxation of the
crystal. Thus,

        dH = dQ + VdP

means that the enthalpy change is the heat change plus the energy the crystal gains by virtue of not
being allowed to expand.
Enthalpy includes the vibrational and bonding energy at absolute zero H0°, plus the energy required to
increase temperature:


        H = H0° +        CPdT

i.e., we can find the enthalpy change         H produced by changing temperature by integrating the heat
capacity CP:


           H=       CPdT

                              Integration Reminder

How to integrate the heat capacity (to determine change in enthalpy          H):


            CP dT =        (a + bT + cT-2 + dT-0.5)

        =aT + bT2/2 - c/T + 2dT0.5

and is evaluated as

        =a(T2 - T1) + b(T22 - T12)/2 - c/(T2-1 - T1-1) + 2d(T20.5 - T10.5)

How to integrate the heat capacity divided by T (to determine entropy S):



                 dT =       (a/T + b + cT-3 + dT-1.5)
= a ln T + b T - c T-2/2 - 2 d T -0.5

and is evaluated as

        a(ln T2 - ln T1) + b(T2 - T1) - c(T2-2 - T1-2)/2 - 2d(T2-0.5 - T1-0.5)




As an example, let's calculate the change in enthalpy H°298-1000 that results from heating quartz
from 298 K to 1000 K, given the following heat capacity expansion coefficients:

a = 104.35, b = 6.07E-3, c = 3.4E+4, d = -1070


                 (CP dT =       (a + bT + cT-2 + dT-0.5)

        =aT + bT2/2 - c/T + 2dT0.5

evaluated from 298 to 1000K

        =a*(1000-298) + b*(10002-2982)/2 - c*(1000-1-298-1) + 2d*(10000.5-2980.5)
        = 45.37 kJ/mol

Relation Among Enthalpy, Heat, and Heat Capacity ( HP= QP)

An important relationship between enthalpy change H and heat change              Q is revealed by
differentiating H = U + PV to obtain the total differential

        dH = dU + PdV + VdP

substituting dU = dQ - PdV we get

        dH = dQ + VdP

dividing by dT gives



             =        -V


at constant pressure,         = 0, leaving



                  =
which is equal to CP:



                     =          = CP

Determining Enthalpies

Thus, if we want to measure how the internal energy U of a crystal changes U with increasing
temperature at constant pressure, we want to know H, and we can get that by integrating the heat
capacity CP over the temperature range of interest.
There's another way to measure H, though: calorimetry. By dissolving a mineral in acid and measuring
the heat produced by the dissolution, we get a heat of dissolution (usually positive). The enthalpy of
"formation" fH° of the mineral is then just the opposite of the heat of dissolution (usually negative).
Exceptions to the "usually positive/negative" rule include CN, HCN, Cu2+, Hg2+, NO, Ag+, and S2-.
Enthalpies of formation appear in tables of thermodynamic data and are usually referenced to 298 K and
1 atm.

Enthalpy of Reaction

To get an enthalpy of reaction rH° we can measure the enthalpies of formation of the reactants and
products fH° and then take the difference between them as

           rH°   =       fH°products-       fH°reactants


For example, we can compute the enthalpy of the reaction

        anhydrite + water = gypsum:
        CaSO4 + 2H2O = CaSO4 2H2O

from
        Ca + S + 2O2 = CaSO4                                      fH°   = -1434.11 kJ/mol

        H2 + 0.5O2 = H2O                                          fH°   = -285.830 kJ/mol

        Ca + S + 3O2 + 2H2 = CaSO4 2H2O                           fH°   = -2022.63 kJ/mol



Thus,

           rH°   =       fH°gypsum      -      fH°anhydrite   -     fH°water   = -16.86 kJ/mol.

Exothermic vs. Endothermic
If rH° < 0 the reaction produces a reduction in enthalpy and is exothermic (heat is given up by the rock
and gained by the surroundings). If rH° > 0 the reaction produces an increase in enthalpy and is
endothermic (heat from the surroundings is consumed by the rock). An easy way to remember this is
that spontaneous reactions produce a decrease in internal energy, and because we know that
UP HP
a decrease in HP is also a decrease in UP.

Calculating         fH°   at Temperatures Other Than 298 K

So far we know how to calculate the change in enthalpy caused by heating and we know that we can get
enthalpies of formation from tables. What if we want to know the enthalpy of formation of a mineral at
a temperature other than 298 K?
We do this by calculating rCP for the reaction that forms the mineral of interest:

          rCP   =       rCPproducts   -   rCPreactants


and then integrating. Thus, for example if we want to know       fH°   for quartz at 1000 K, we get
coefficients for the heat capacities of Si, O2 and SiO2:
compound            a            b                 c        d

Si            31.778 5.3878E-4 -1.4654E5 -1.7864E2

O2            48.318 -6.9132E-4 4.9923E5 -4.2066E2

SiO2          104.35 6.07E-3                 3.4E-4      -1070



for the reaction

        Si + O2 = SiO2

and we calculate
  a = 24.254
  b = 6.2225E-3
  c = -3.5E5
  d = -470.7
and thus,


          fH°1000  - fH°298 =       CP dT = a*(1000-298) +             b/2*(10002-2982) -   c*(1000-1-298-1)
                       0.5    0.5
        +2      d*(1000 -298 ) = 5.511 kJ/mol
This is the change in the enthalpy of formation that results from heating. We add this to the enthalpy of
formation at 298 K to get the enthalpy of formation at 1000 K:

           fH°1000   =(     fH°1000   -   fH°298)   +   fH°298   = 5.511 - 910.700 = -905.2 kJ/mol

In other words, forming quartz from the elements at 1000 K yields slightly less heat than at 298 K.
Compare this with the change in enthalpy H°298-1000 that results from heating quartz from 298 K to
1000 K, which we calculated is 45.37 kJ/mol.

Entropy

We have discussed the intuitive statement that reactions probably proceed because the reactants can
decrease their internal energy by reacting. We also noted that internal energy scales with enthalpy,
suggesting that reactions might 'go' because of a decrease in enthalpy. However, we then noted that not
all reactions give off heat--some, such as the melting of ice, proceed in spite of consuming heat.
Moreover, there are other processes that proceed in the apparent absence of any heat change: e.g.,
mixing of gases or the spreading of dye in water. What is it that causes these reactions to proceed
spontaneously even if the heat change is zero or endothermic?
The answer is entropy S, which is a measure of the order or disorder. Entropy has three sources:
configurational, electronic, and vibrational.




Configurational entropy refers to the entropy resulting from imperfect mixing of different
atoms in the same site in a crystal, and is described by the Boltzmann distribution:

        Sconfigurational = k ln   (This is engraved on Boltzmann's tomb in Vienna!)

where is the probability that a given number of atoms in a given number of sites will have a particular
configuration.
For N atomic sites that can contain fraction XA A atoms and XB B atoms,



           =
N is always large where moles of material are concerned, so we can simplify this (using Stirling's
approximation) to

        S = - n R (XA ln XA + XB ln XB)

where n is the number of sites per mole. For example in cordierite there are 4 Al atoms and 5 Si atoms
distributed over 9 tetrahedral sites. For a random distribution the entropy is

        S = - 9 R (4/9 ln 4/9 + 5/9 ln 5/9) = 51.39 J mol-1 K-1

Note that the form of the configurational entropy equation (and electronic entropy as well) indicates
that if XA or XB are 0 or 1, Sconfig is zero:




Electronic entropy arises when an electron in an unfilled orbital can occupy more than one orbital; e.g.,
for Ti3+, the single 3d electron can occupy one of three possible t2g orbitals and Selectronic = 9 J mol-1 K-1.
Vibrational (or calorimetric) entropy arises because the energy of lattice vibrations can only increase or
decrease in discrete steps and the energy quanta (phonons) can be distributed within the possible
energy steps in different ways. Vibrational entropy is very difficult to calculate from statistical mechanics
but can be calculated easily from heat capacity. Here's why:
The entropy of a system always increases during irreversible processes; i.e., for a reversible process, dS =
0, whereas for irreversible processes dS >0. This is the Second Law of Thermo--better known as "You
can't feed s**t into the rear of a horse and get hay out the front."
If a mineral becomes more ordered during a reaction, reducing its entropy, the heat liberated must
increase the entropy of the surroundings by an even greater amount. Thus, we write



        dS >

then
>

and recalling that



        CP =

then



               >

and



        S=               dT

In other words, the vibrational entropy can be found by integrating the heat capacity divided by
temperature.
In a perfectly ordered, pure crystalline material the entropy is zero. This is a simple statement of the
Third Law of Thermo, which follows from the fact that heat capacities approach zero at zero K:


                   C=0

However, because the rate of atomic diffusion also goes to zero at 0 K, all compounds have some zero-
point entropy S°0.
Entropy is thus the only thermodynamic potential for which we can calculate an absolute value. What
we typically do is determine the heat capacity from near absolute zero to ambient conditions and then
integrate it to get the (absolute) entropy (in fact this gives us only the vibrational entropy and ignores
configurational and electronic contributions to entropy).
Entropy Change of Reaction

Just like rH and rV, we can calculate entropies of reactions by using absolute entropies S and
calculating a difference in entropy rS. For example, if we know that

           S°CaSO4 = 106.7 J mol-1 K-1
           S°Ca = 41.42 J mol-1 K-1
           S°S = 31.80 J mol-1 K-1
           S°O2 = 205.138 J mol-1 K-1

then the entropy of the reaction

           Ca + S + 2O2 = CaSO4

is   rS°   = 106.7 - 41.42 - 31.80 - 2 * 205.138 = -376.8 J mol-1 K-1
Energy Associated With Entropy

The units of entropy suggest that the energy associated with S scales with temperature:

        dU    -TS

(The minus sign is there for reasons similar to the -PV we encountered earlier.)
The energy associated with configurational entropy in the Al4Si5 cordierite we talked about earlier looks
like this:




The energy associated with vibrational entropy in tremolite, quartz, and chalcopyrite looks like
this:




(Josiah Willard) Gibbs Free Energy of a Phase

The Gibbs free energy G is the thermodynamic potential that tells us which way a reaction goes at a
given set of physical conditions--neither the enthalpy change nor the entropy change for a reaction
alone can provide us with this information. The two measures of energy (enthalpy H and entropic
energy TS) are brought together in the Gibbs free energy equation: (the chemical potential is the
equivalent for a component)

        G = U + PV - TS

which says that the Gibbs free energy G is the internal energy of the crystal U plus the energy the crystal
gains by virtue of not being allowed to expand minus the entropic energy TS. Recalling that

        H = U + PV

we can write this in a more understandable way

        G = H - TS

which says that G is the difference between the heat energy and the entropic energy.




Relationship Among G, S, and V

If we differentiate

        G = U + PV - TS

to obtain

        dG = dU + PdV + VdP - TdS - SdT

and substitute
TdS = dU + PdV

(this comes from dS = dQ/T and dU = dQ - PdV); we are left with

        dG = VdP - SdT

meaning that changes in Gibbs free energy are produced by changes in pressure and temperature acting
on the volume and entropy of a phase.
Realize that when we write

        dG = VdP - SdT

we are implicitly writing


        dG =      dP -      dT

which means that



                =V

and



                = -S
These relations indicate that the change in Gibbs free energy with respect to pressure is the molar
volume V and the change in Gibbs free energy with respect to temperature is minus the entropy S.




Gibbs Free Energy of Formation

The defining equation for Gibbs free energy

        G = H - TS

can be written as

          G=        H-T         S

such that the Gibbs free energy of formation    fG°   is

          fG°   =    fH°   -T       fS°


For example, to calculate the Gibbs free energy of formation of anhydrite, we can use

           fH°CaSO4 = -1434.11 kJ/mole
        S°CaSO4 = 106.7 J mol-1 K-1
        S°Ca = 41.42 J mol-1 K-1
S°S = 31.80 J mol-1 K-1
        S°O2 = 205.138 J mol-1 K-1

and we calculate the entropy of formation of anhydrite

          fS°   = S°CaSO4 - S°Ca - S°S - 2 * S°O2 = -376.796 J mol-1 K-1

and then use

          fG°   =    fH°   -T    fS°   = -1434,110 - 298.15 * -376.796 = -1321.77 kJ/mol

Gibbs Free Energy of Reaction

We can write the Gibbs free energy of reaction as the enthalpy change of reaction minus the entropic
energy change of reaction

          rG    =    rH   -T    rS


If the heat energy equals the entropic energy

          rH    =T    rS


then

          rG    =0

and there is no reaction. Finally we have come to a satisfying point--we can now determine whether a
given reaction will occur if we know H and S, and both of these are measurable or can be
calculated.
If rG < 0, the Gibbs free energy of the products is lower than the Gibbs free energy of the reactants
and the reaction moves to produce more products. If rG > 0, the Gibbs free energy of the products is
greater than the Gibbs free energy of the reactants and the reaction moves to produce more reactants.
For example, to calculate rG° at STP for the reaction

         aragonite = calcite

we use

           rH°   = 370 J
           rS°   = 3.7 J mol-1 K-1

to calculate

           rG°   = 370 - 298.15 * 3.7 = -733 J/mol

The negative value of G tells us that calcite has lower Gibbs free energy and that the reaction runs
forward (aragonite   calcite).

Clapeyron Relation

There is a useful relation between the slope of a reaction in PT space (i.e., dP/dT) and the entropy and
volume changes of the reaction that follows from

           rG    =   VrdP -    SrdT

At equilibrium       G = 0, such that
rVdP      =     rSdT


or



            =

So, the P-T slope of a reaction is equal to the ratio of the entropy change to the volume change.
Alternatively, along the equilibrium curve, the changes in pressure times the volume change are equal to
changes in temperature times the entropy change. This is the Clapeyron Equation.




So, a phase diagram is a kind of free energy map.                  =   along an equilibrium,   <   at
high P and low T, and      >     at high T and low P. Along the equilibrium boundary the Gibbs
Free energies of the reactants and products are equal and the Gibbs Free energy of reaction rG,
is zero.

Shortcutting        H and         S and Finding       G Directly

Like other thermodynamic potentials, we can write the change in Gibbs free energy of reaction as

          rG°   =       fG°reactants-   fG°products


Instead of using fH° and fS°, it is often possible to obtain fG° values for most compounds from
electronic data bases. For example, if the following Gibbs free energies of formation are known:

          fG°CaSO4      = -1707.280 kJ/mol
                        2H2O
          fG°CaSO4 = -1321.790 kJ/mol
          fG°H2O = -237.129 kJ/mol
then for

        CaSO4 + 2H2O = CaSO4 2H2O
          rG° = -1.232 kJ/mol


Gibbs Free Energy at Any Pressure and Temperature

We know many ways to determine rG at STP--but how do we calculate rG for other pressures and
temperatures? Recall that the changes in Gibbs free energy with pressure and temperature are given by
two of Maxwell's relations



                             =        rV      and                   =-   rS


If we recast these as

                       =      rV      P
        and
                       =-        rS       T

and integrate, we get



                       rGdP      =        rGP     -   rGPref   =         rVdP
        or

             rGP   =        rGPref    +               rVdP


and



                       rGdT      =        rGT     -   rGTref   =-         rSdT
        or

             rGT   =        rGTref    -               rSdT


thus



             rGPT   =        rGPrefTref       +            rVdP     -         rSdT


Solving the Pressure Integral at Constant Temperature

To a first approximation, we can ignore the expansivity and compressibility of solids and use
rVsdP        =       rVs(P      - 1)

as a simplification. Don't forget that this approximation is valid for solids only! An even more common
assumption for P>>1 is



                            rVsdP        =       rVsP


For example, calculate the change in Gibbs free energy for the reaction
2 jadeite = albite + nepheline
if pressure increases from 1 bar to 10 kbar, given


           nepheline = 54.16 cm3
                               3
           albite = 100.43 cm
                              3
           jadeite = 60.40 cm


First we calculate        rV    and find


           r        =   nepheline    +        albite   -2     jadeite   = 33.79 cm3 = 3.379 J/bar

and thus

           rGPT     -   rG1,T    =       rVsP    = 33.79 kJ/mol

Solving the Temperature Integral at Constant Pressure

Recall that the effect of temperature on the entropy change of reaction                             rS   depends on the heat
capacity change of reaction rCP:



           rS   =                        dT

Thus



           rGT   =      rGTref   -                rSdT


expands to



           rGT   =      rGTref   -                     STref +                  dT dT

If the form of the heat capacity expansion is
CP = a + bT + cT-2 + dT-0.5

then the above double integral is

           a(T - T ln T) - bT2/2 - cT-1/2 + 4 dT0.5 - aTref - bTref2/2 +                             cTref-1 - 2   dTref0.5 +
        aTlnTref + bTTref - cTTref-2/2 - 2 dTTref-0.5 - T rSTref + Tref rSTref

Note that this considers only vibrational entropy and ignores configurational entropy. This means of
solving for rG requires that you know rG at the reference temperature.
An alternative path that requires that you know the enthalpy change rH at the reference temperature
is



           rGT   =     rHTref   +       CPdT - T          rSTref   +                dT

Solving the Temperature and Pressure Integrals for                          rGP,T


To calculate the Gibbs free energy change of a reaction at any pressure and temperature, we can use
either of the following equations, depending on whether we know rH or rG



           rGP,T   =    rG1,Tref    -       rSTref   +                     dT dT +       rVsP



           rGP,T   =    rH1,Tref    +      CPdT - T          rSTref    +             dT         +   rVsP


If you don't have heat capacity data for the reaction of interest, these equations can be roughly
approximated as

           rGP,T =      rG1,Tref - rS1,Tref(T - Tref) +      rVsP
           rGP,T =      rH1,Tref - T rS1,Tref + rVsP

For example, calculate rG for jadeite + quartz = albite at 800 K and 20 kbar. The data at 298 K and 1
bar are
  rH° = 15.86 kJ/mol
                 -1   -1
  rS° = 51.47 J K mol
                                 3
  rVs° = 1.7342 J/bar = 17.342 cm /mol
Using

           rGP,T =  rH1,Tref - T rS1,Tref + rVsP
        = 15,860 - 800 * 51.47 + 1.7342 * 20,000 = 9.37 kJ/mol

If we had used the complete equation for solids, integrating the heat capacities, we would have
obtained an answer of 9.86 kJ/mol--not horrifically different.
Calculating the PT Position of a Reaction

If we say that rG = 0 at equilibrium, then we can write our solids-only and constant-heat-capacity
approximations as

        0=     rG1,T   -    rS1,Tref(T  - Tref) + rVsP
        0=     rH1,Tref    -T    rS1,Tref +     rVsP


and thus we can calculate the pressure of a reaction at different temperatures by


        P=       rG1,Tref   -     rS1,Tref(T     - Tref)    /-     rVs


        P=       rH1,Tref   -T        rS1,Tref    /-       rVs


and we can calculate the temperature of a reaction at different pressures by


        T = Tref +         rG1,Tref   +     rVsP       /     rS1,Tref


        T = Tref +         rH1,Tref   +     rVsP       /     rS1,Tref


Let's do this for the albite = jadeite + quartz reaction at T = 400 K and T = 1000 K:

        P = (15,860 - 5147 * 400) / -1.7342 = 2.7 kbar
        P = (15,860 - 5147 * 1000) / -1.7342 = 20.6 kbar

Assuming that dP/dT is constant (a bad assumption, we know), the reaction looks like this




Introduction to the Equilibrium Constant

A bit farther down the road we will encounter a monster called the equilibrium constant K:

        K = exp(-      rG°/RT)
or

        ln K = -   rG°/RT


At equilibrium, where       rG°=   0, ln K = 0 and K = 1. Let's see what K looks like for jadeite + quartz = albite
at 800 K and 20 kbar:

        ln K = - ( rH1,Tref - T rSTref + rVsP)/ RT
        = -(15,860 - 800 * 51.47 + 1.7342 * 20,000)/(8.314*800) = -1.4

If we do this for all of PT space, we can contour PT space in terms of lnK:




Solutions
Almost no phases are pure, but typically are mixtures of components. For example, olivine varies from
pure forsterite Mg2SiO4 to pure fayalite Fe2SiO4, and can have any composition in between--it is a solid
solution. We need a way to calculate the thermodynamic properties of such solutions.
As a measure of convenience, we use mole fraction to describe the compositions of phases that are solid
solutions. For example, a mix of 1 part forsterite and 3 parts fayalite yields an olivine with 25 mol%
forsterite and 75 mol% fayalite, which can be written as (Mg0.25Fe0.75)2SiO4 or fo25fa75, etc. Mole fractions
are denoted as Xi.
We need a way of splitting up the Gibbs free energy of a phase among the various components of the
phase--how for example do we decide how much of the Gibbs free energy of an olivine is related to the
forsterite component and how much derives from the fayalite component? Likewise, how does the
Gibbs free energy of a phase vary with composition--is the relationship linear between endmembers??
We address these issues by defining a partial Gibbs free energy for each component at constant
pressure and temperature and constant composition of other components, called the partial molar
Gibbs free energy or chemical potential




           i   =

where n is the amount of substance. For olivine solid solution composed of fayalite and forsterite
components or endmembers, we write


        dG =          dnfayalite +        dnforsterite

Volume of Mixing

Imagine that mole fractions of phase A and phase B with molar volumes VA and VB, are mixed together.
We can describe the volume of the mixture as

        V = XAVA° + XBVB°

and it is a linear mixing of the two endmember volumes. We call this ideal mixing or mechanical mixing.
Real solutions, however, do not behave this way, and the mixing is always non ideal, although
sometimes only weakly so. The figure shows mixing that produces a smaller volume than expected, but
it is not possible to predict the shapes and positions of such mixing curves.
Partial Molar Volume

The partial molar volume is defined as




           i


If you mix two compounds A and B together and find a volume of mixing that is non-ideal, how can you
determine the contribution that A and B each make to the volume? That is, what are the partial molar
volumes of A and B, A and B?? Graphically, the partial molar volumes are the A and B axis intercepts
of the tangent to the mixing curve, and can be described by the simple relationship:

        Vmix = XA A + XB    B
        or
        Vmix = Xi i

The behavior of this function is such that when XA is 1, Vmix = VA and when XA is 0, Vmix = VB. Alternatively,
A   = (Vmix - XB   B)   / XA

Entropy of Mixing

The entropy of mixing is never zero because mixing increases entropy. As we discussed days ago, the
entropy of mixing (i.e., the configurational entropy) is

           Smix = -R      (Xi ln Xi)

where i = 1..n is the number of sites over which mixing is occurring.

Enthalpy of Mixing

Enthalpies also do not combined ideally (linearly) in mixtures because the mixture may have stronger
bonds than were present in either of the unmixed phases. The excess enthalpy is

           Hmix = 0.5 * N z XAXB [2       AB   -   AA   -   BB]


where AB is the interaction energy among A-B atoms,               AA   is the interaction energy among A-A atoms,
and BB is the interaction energy among B-B atoms.

Gibbs Free Energy of Mixing

Recall that all spontaneous processes/reactions occur because of a decrease in Gibbs free energy. It
should therefore not surprise you that the Gibbs free energy of mixing is always negative--otherwise
mixing would not occur. The fact that A < G°A and B < G°B illustrates why compounds combine
spontaneously--each compound is able to lower its free energy.
The above figure is hypothetical because we cannot measure or calculate the absolute Gibbs free
energy of phases. For this reason, is always expressed as a difference from some standard state
measurement, as       , - °, or - G°.
The difference between the absolute Gibbs free energy G° per mole ° of a pure compound and
the chemical potential per mole of dissolved compound is

          A   - G°A =   A   -   °A = RT lnXA

This function has the following shape:
implying that when the mineral is pure (X = 1) then       = 0, and when the mineral is infinitely
dilute (X = 0) then the chemical potential is undefined. For example, in a two-component
mineral if XA = 0.4, at T = 298 K,

          A-    °A = 8.314 * 298 ln 0.4 = -2271 J
          B-    °B = 8.314 * 298 ln 0.6 = -1266 J

The equation of the    Gmix line is the sum of the chemical potentials of the endmembers:

          Gmix = RT (XA ln XA + XB ln XB) or
          Gmix = RT (Xi ln Xi)

which looks like this for two components:




Actually, all this discussion has been predicated on the assumption that Hmix = 0. If this is not
true, Gmix is not a simple function of composition, but has the general form:
Depending on the relative values of Hmix and -T Smix, the free energy of mixing may be
negative throughout the whole composition range if the entropic energy contribution outweighs
the enthalpy increase; this is more likely at higher temperature.
The two free energy minima in the above figure indicate that minerals of intermediate
compositions can reduce their free energy by unmixing into two phases. This explains the
appearance and driving force for exsolution. Note that this can only be true if Hmix > 0, i.e., if
2 AB > AA + BB, which makes sense because it means that the A-B bonds have a higher free
energy than the sum of the free energies of separate AA and BB bonds.

Activities

In reality, no phases behave ideally--that is, their chemical potentials are never simple logarithmic
functions of composition as

             A   -   °A = RT lnXA

implies. Instead, we say that the chemical potential is a simple logarithmic function of activity and
define activity as

a = ( X)
where a is the activity of a compound,        is the "site occupancy coefficient" (e.g.,   = 2 for Mg in
Mg2SiO4), and        is the activity coefficient that describes the non-ideal behavior. Thus we write

             A   -   °A = RT lnaA

For pure compounds a=1 because X=1. For ideal compounds =1. As a specific example, the chemical
potential of the almandine (Fe3Al2Si3O12) component of a garnet solid solution ((Fe, Mg, Ca,
Mn)3Al2Si3O12) is

             alm =      °alm + RT lnXalm
To be clear, ° is the chemical potential of the component in its pure reference state and varies as a
function of pressure and temperature; this we measure with calorimetry. is the chemical potential as
it actually occurs and varies as a function of phase composition; this we measure with an electron
microprobe. The activity forms a bridge between idealized behavior and real behavior.

The Equilibrium Constant

At equilibrium the sum of the Gibbs free energies of the reactants equals the sum of the Gibbs free
energies of the products. Equally, the sum of the partial molar Gibbs free energies (chemical potentials)
of the reactants equals the sum of the partial molar Gibbs free energies (chemical potentials) of the
products. In other words, for

        SiO2 + 2H2O = H4SiO4

at equilibrium,

            H4SiO4 =         SiO2 + 2    H2O

More generally, for

        aA + bB = cC + dD

then

        c       C+d    D=a         A+b    B

or, at equilibrium

            r    =0=c         C+d       D-a    A-b   B

which we can reformat as


            r    =       i     i


where i is the stochiometric coefficient of a product or reactant and is positive if for a product and
negative if for a reactant. If we then remember that

            -     ° = RT lna

and rewrite it as

            =     ° + RT lna

we can reformat the earlier equation as
r     = 0 = c(     C°   + RT lnaC) + d(   D°   + RT lnaD) - a(   A°   + RT lnaA) - b(   B°   + RT lnaB)

which looks nicer as

           r     =      r   ° + RT ln (aCc aDd/aAa aBb)

To be completely general we write


           r     =      r   ° + RT ln      ai   (    means to multiply all i terms)

This equation is invariably simplified to

           r     =      r   ° + RT lnQ

and Q is the activity product ratio. The activities in the Q term change as the reaction progresses toward
equilibrium.
To be clear again, r ° is the difference in the Gibbs free energies of the products and reactants when
each is in its pure reference state and varies as a function of pressure and temperature. r is the
difference in the Gibbs free energies of the products and reactants as they actually occur and varies as a
function of phase composition.
At equilibrium, the product and reactant activities have adjusted themselves such that r = 0. We
write this (with K instead of Q, to signify equilibrium) as

        0=       rG°   = -RT ln K

K is called the equilibrium constant. If K is very large (ln K positive), the combined activities of the
reaction products are enormous relative to the combined activities of the reactants and the reaction will
likely progress. On the other hand, if K is small (ln K negative), there is unlikely to be any reaction.
The utility of K is that it tells us for any reaction and any pressure and temperature, what the activity
ratios of the phases will be at equilibrium. For example, for the reaction

        albite = jadeite + quartz

let's say that at a particular P and T,

           rG°   = -20.12 kJ/mol

Using

           rG°   = -RT lnK

we calculate
log K = 3.52

This means that at equilibrium,

        (ajadeite aquartz / aNaAlSi3O8) = e3.52

Where ajadeite is the activity of NaAlSi2O6 in clinopyroxene and aalbite is the activity of NaAlSi3O8 in
plagioclase.

Alternative Route to the Equilibrium Constant

When we think of mass balance in a reaction, we can explicitly write

        0=            iMi


where i are the stoichiometric coefficients and Mi are the masses or the phase components.
Analogously, we can explicitly write a similar balance among the chemical potentials:

        0=            i     i


For each chemical potential we can write

           i=         °i + RT lnai

Combining these two equations we find

        0=            i     °i +      iRTln   ai

        0=            i     °i +   RTln (ai)

        0=            i     °i + RTln ai
        0=            i     °i + RTln K

and eventually

        0=       rG°      + RT ln K

or

           rG°   = -RT ln K

The equation


        K=       ai
is the law of mass action (which actually discusses the action of chemical potential rather than mass).
We can also write for 298 K and 1 atm

            rH°   -T       rS°   = - RT ln K

and for any P and T of interest:



            rH1,Tref   +             CPdT - T           rSTref   +                dT   +   rVP   = - RT ln K

This has been called "the most important equation in thermodynamics," so you'd better like it(!) The
equilibrium constant K is a function of 1/T

         -ln K = (     rG°   / RT) = [(        rH   / RT) - (        rS   / R)]




Which looks like

Activity Models (Activity-Composition Relations) for Crystalline Solutions

Garnets are solid solutions of

component abbrev.                 Formula

pyrope        prp           Mg3Al2Si3O12

almandine alm               Fe3Al2Si3O12

grossular     grs           Ca3Al2Si3O12

spessartine sps             Mn3Al2Si3O12

andradite     and           Ca3Fe23+Si3O12


Mixing models derive from entropy considerations. In particular the relation
Smix = -R           Xi ln Xi

although we will not go through the derivation.

Mixing on a Single Site

The simplest type of useful activity model is the ionic model, wherein we assume that mixing occurs on
crystallographic sites. For a Mg-Fe-Ca-Mn garnet with mixing on one site, which we can idealize as
(A,B,C,D) Al2Si3O12, the activities are

                          3     3
        aprp =        Mg XMg
                         3    3
        aalm =         Fe XFe
                         3   3
        agrs =        Ca XCa
                          3     3
        asps =        Mn XMn




The pyrope activity is shown in the above figure.
In general, for ideal mixing in a mineral with a single crystallographic site that can contain
ions,


        ai = Xj

where a, the activity of component i, is the mole fraction of element j raised to the   power. For non-
ideal mixing, we include an activity coefficient


        ai =      j    Xj

Mixing on a Several Sites

For minerals with two distinct sites and the general formula


        (A,B) (Y,Z)
there are four possible end member components A Y , A Z , B Y , and B Z .
The ideal activities of these components are


        aA   Y   = XA XY

        aA   Z   = XA XZ

        aB   Y   = XB XY

        aB   Z   = XB XZ

For non-ideal garnet activities we write

        aprp = XMg3 XAl2 or Mg3 XMg3 Al2 XAl2
        aalm = XFe3 XAl2 or Fe3 XFe3 Al2 XAl2
        agrs = XCa3 XAl2 or Ca3 XCa3 Al2 XAl2
        asps = XMn3 XAl2 or Mn3 XMn3 Al2 XAl2
        aand = XCa3 XFe3+2 or Ca3 XMn3 Fe3+2 XFe3+2

where the X3 term describes mixing on the 8-fold trivalent site and the X2 term describes mixing on the
octahedral divalent site.




The pyrope activity is shown in the above figure for Mg from 0       3 and Al from 0    2.
It is common to modify such models that are based on completely random mixing of elements
with models that consider local charge balance on certain sites or the Al-avoidance principle.

Geothermometry and Geobarometry

Exchange Reactions

Many thermometers are based on exchange reactions, which are reactions that exchange elements but
preserve reactant and product phases. For example:
Fe3Al2Si3O12        + KMg3AlSi3O10(OH)2 = Mg3Al2Si3O12 + KFe3AlSi3O10(OH)2

        almandine           + phlogopite          = pyrope         + annite


We can reduce this reaction to a simple exchange vector:

        (FeMg)gar+1 = (FeMg)bio-1

Popular thermometers include garnet-biotite (GARB), garnet-clinopyroxene, garnet-hornblende, and
clinopyroxene-orthopyroxene; all of these are based on the exchange of Fe and Mg, and are excellent
thermometers because rV is small, such that



            =

is large (i.e., the reactions have steep slopes and are little influenced by pressure). Let's write the
equilibrium constant for the GARB exchange reaction

        K = (aprpaann)/(aalmaphl)

thus

           rG   = -RT ln (aprpaann)/(aalmaphl)


This equation implies that the activities of the Fe and Mg components of biotite and garnet are a
function of Gibbs free energy change and thus are functions of pressure and temperature.
If we assume ideal behavior (        = 1) in garnet and biotite and assume that there is mixing on only 1 site

        aalm = Xalm3 = [Fe/(Fe + Mg + Ca + Mn)]3
        aprp = Xprp3 = [Mg/(Fe + Mg)]3
        aann = Xann3 = [Fe/(Fe + Mg)]3
        aphl = Xphl3 = [Mg/(Fe + Mg)]3

Thus the equilibrium constant is

        K = (XMggar XFebio)/(XFegar XMgbio)

When discussing element partitioning it is common to define a distribution coefficient KD, which is just
the equilibrium constant without the exponent (this just describes the partitioning of elements and not
the partitioning of chemical potential):

        KD = (XMggar XFebio)/(XFegar XMgbio) = (Mg/Fe)gar /(Mg/Fe)bio = K1/3
Long before most of you were playground bullies (1978) a couple of deities named John Ferry and Frank
Spear measured experimentally the distribution of Fe and Mg between biotite and garnet at 2 kbar and
found the following relationship:




If you compare their empirical equation

        ln KD = -2109 / T + 0.782

this immediately reminds you of

        ln K = - (     rG°   / RT) = -(    rH   / RT) - (P   rV   / RT) + (   rS   / R)

and you realize that for this reaction

             rS   = 3*0.782*R = 19.51 J/mol K

(the three comes from the site occupancy coefficient; i.e., K = KD3) and

        -(    rH   / R) - (P    rV   / R) = -2109

or

             rH   = 3*2109*R -2070*          rV


Molar volume measurements show that for this exchange reaction                            rV   = 0.238 J/bar, thus

             rH   = 52.11 kJ/mol

The full equation is then
52,110 - 19.51*T(K) + 0.238*P(bar) + 3RT ln KD = 0

To plot the KD lines in PT space




Net-Transfer Reactions

Net-transfer reactions are those that cause phases to appear or disappear. Geobarometers are often
based on net-transfer reactions because rV is large and relatively insensitive to temperature. A
popular one is GASP:

        3CaAl2Si2O8            = Ca3Al2Si3O12 + 2Al2SiO5 + SiO2

        anorthite              = grossular       + kyanite + quartz


which describes the high-pressure breakdown of anorthite.



For this reaction

             rG   = -RT ln [(aqtzaky2agrs) / aan3] = -RT ln agrs / aan3

(the activities of quartz and kyanite are one because they are pure phases). A best fit through the
experimental data for this reaction by Andrea Koziol and Bob Newton yields

        P(bar) = 22.80 T(K) - 7317

for   rV   = -6.608 J/bar. Again, if we use
ln K = -(      rH   / RT) - (P              rV   / RT) + (        rS   / R)

and set ln K = 0 to calculate values at equilibrium, we can rewrite the above as

        (P   rV   / R) = -(           rH   / R) + (T          rS   / R)

or

        P=T       rS   /     rV   -        rH   /        rV


if T rS / rV = 22.8 then rS = -150.66 J/mol K
if rH / rV = 7317 then rH = -48.357 kJ/mol
So, we can write the whole shmear as

        0 = -48,357 + 150.66 T(K) -6.608 P (bar) + RT ln K

Contours of ln K on a PT diagram for GASP look like this:




Kinetics

Thermodynamics places no constraints on the rate or mechanism of reaction--that is the realm of
kinetics. A popular method for describing the rate at which reactions proceed is to talk of an activated
state through which the reaction must pass:
When a system passes from an initial to a final state it must overcome an activation energy
barrier G*.
The advantages of this activation energy barrier paradigm are that it qualitatively explains the
i) persistence of metastable states; ii) effect of catalysts in lowering G*; iii) temperature
dependence of transformation. We can draw a similar diagram for a change in enthalpy induced
by the reaction rH and an activation enthalpy barrier H* (usually called an activation
energy Q*). Of course, unlike rG, rH can be positive or negative:




It is not easy to generalize about the activation entropy S*, however, in general, reactions with
positive entropy change rS are faster. For example, evaporation is faster than condensation,
melting is faster than crystallization, and disordering is faster than ordering.
Because thermal energy dictates whether an atom has sufficient energy to overcome an
activation energy barrier, we will write that the fraction of atoms with thermal energy greater
than H* is

       f = exp ( -   H*/RT)
i.e., if f << 1, few atoms have enough thermal energy to overcome the activation energy barrier,
whereas if f = 1 all atoms can overcome the activation energy barrier.




For reactions that involve a single step characterized by a single activation energy, the rate of the
reaction depends on the i) frequency with which atoms attempt to jump from one site to the next
  ; ii) fraction of atoms with thermal energy greater than Q*; and iii) probability p that the atom
jumping satisfies some geometrical consideration (this is a fancy name for a fudge factor):

        rate    p   exp(-Q*/RT)

Often this is rewritten as rate   (kT/h)   exp(-Q*/RT)




where k is Boltzmann's constant, and h is Planck's constant. Thus, the rate   at which atoms jump is
related to temperature and to atom-scale processes described by k and h.

Nucleation

Most transformations take place by nucleation and growth. The driving force for nucleation results from
the fact that the formation of the new phase lowers the total free energy by VG, the Gibbs free
energy change of reaction per unit volume. Nucleation is opposed by an interfacial energy and a
strain energy . The overall change in nucleation energy for a spherical nucleus of radius r is then
   nG =    VG +    Ginterfacial + Gstrain = (4/3) r3 VG + 4 r2 + (4/3) r3
These different energy contributions yield an increase in total free energy up to a certain radius termed
the critical radius, beyond which the total free energy decreases.
This change from increasing to decreasing nucleation free energy happens because the
surface:volume ratio decreases with increasing radius, so the negative volume free energy term
that favors nucleation eventually overwhelms the positive surface and strain free energy terms
that oppose nucleation. We can re-order the terms in the above equation to calculate the critical
size of the nucleus rc

         rc = -2     /(   VG      +    )

If, at the critical radius,       nG   =    G*, the activation energy for nucleation is

                              3
            G* = 16               / 3(     VG   +   )2

Growth

Following nucleation, grains of the product phase(s) grow to replace the parent phase(s). Either the
reaction is polymorphic, or atoms of the parent phase must dissolve, be transported, and then attach
themselves to the product phase. The rate of growth is thus controlled by the rate of the slowest of
these three steps, and is described as either interface controlled or diffusion controlled.
Turnbull's (1956) formulation to quantify interface-controlled growth rate                is:

            =      (kT/h) exp( -Q*/RT)[( -          rG/RT)]


where is an "interface jump distance" and the rest you will recognize from previous equations. The [( -
  rG/RT)] term indicates that the rate of growth depends on the Gibbs free energy change of reaction.

As rG      0, this term also approaches zero. As rG        , this term approaches 1.

Transformation: Nucleation + Growth
A complete transformation involves nucleation and growth--the product phases must form and grow
and the parent phases must be consumed. The letter _ is often used to indicate 'reaction progress' or
'degree of transformation,' and varies from 0 (no reaction) to 1 (complete reaction). The transformation
is the time-integrated result of ongoing nucleation and growth, which can vary in time and space:


           = 1 - exp[(4/3)              dt]

Just as an example, the general rate equation for interface-controlled (i.e., not diffusion-controlled)
growth of nuclei formed on grain boundaries is


                                                       2
           = 1 - exp{(6.7/d)        [1-exp(        [   (t -   )2 - y2] d )] dy}

In their simplest form, these equations have the form


           = 1 - exp(-ktn)

Flip this around to


        exp(-ktn) = 1 -

linearize by means of logarithms


        -ktn = ln (1 -    )

change signs and cleverly insert ln 1


        ktn = ln 1 - ln (1 -    )

rewrite the two logarithms as one, recalling that ln (a/b) = ln a - ln b


        ktn = ln [1 / (1 -     )]

and linearize once more with logarithms to get the final glorious equation


        n ln t + ln k = ln [ ln (1 -    )]

The Last Supper: A Still Life of Thermodynamics & Kinetics

 Zeolites, like laumontite and wairakite, form in oil fields as alteration products of plagioclase and other
 Ca-bearing phases. The thermodynamic properties ( H, S, V, CP) of zeolites have been measured, and
              we can use those properties to calculate a phase diagram for the CASH system:
Laumontite is the phase that is stable at the lowest P and T. Wairakite is the next phase to form, and it
     does so via the reaction laumontite _ wairakite + H2O. At higher temperature wairakite + H2O
                                 decompose to anorthite + quartz + H2O.



      Kinetic experiments conducted on the reaction laumontite _ wairakite + H2O, using crystals of
        laumontite suspended in H2O, reveal the transformation vs. time data in the figure above.


                                              One could use the equation

 to interpret the two sub-figures to reveal different n and k values for each temperature. This is the way
rate data were interpreted in the bad old days, but this approach lacks any physical or mechanistic basis.
  Instead, we can measure the rate of growth at each temperature and relate the rate of growth to the
  Turnbull equation. Above is an example of grain growth data collected for 450°C. The rate of growth is
  interpreted to be a constant 2.0 ± 0.3 E-10 m/s. If growth rate data like this can be collected for every
                temperature of interest, an activation energy for growth can be calculated:


 The activation energy for growth apparently varies from ~196 kJ/mol to ~ 72 kJ/mol depending on the
reaction mechanism. The growth rate data can be combined with similar nucleation rate data to yield a
complete transformation rate equation that can be extrapolated to geologic conditions of interest. The
  figure below shows extrapolated growth rates (m/s) for the laumontite _ wairakite + H2O reaction.
search



  Potentials


                       Free energy · Free entropy




                  Internal energy        U(S,V)
                      Enthalpy       H(S,p) = U + pV
               Helmholtz free energy A(T,V) = U − TS
                Gibbs free energy G(T,p) = H − TS




The four laws of thermodynamics define fundamental physical quantities (temperature, energy, and
entropy) that characterize thermodynamic systems. The laws describe how these quantities behave
under various circumstances, and forbid certain phenomena (such as perpetual motion).

The four laws of thermodynamics are:[1][2][3][4][5][6]
Zeroth law of thermodynamics: If two systems are in thermal equilibrium with a third system,
        they must be in thermal equilibrium with each other. This law helps define the notion of
        temperature.

        First law of thermodynamics: Heat and work are forms of energy transfer. Energy is invariably
        conserved but the internal energy of a closed system changes as heat and work are transferred
        in or out of it. Equivalently, perpetual motion machines of the first kind are impossible.

        Second law of thermodynamics: The entropy of any isolated system not in thermal
        equilibrium almost always increases. Isolated systems spontaneously evolve towards thermal
        equilibrium—the state of maximum entropy of the system—in a process known as
        "thermalization". Equivalently, perpetual motion machines of the second kind are impossible.

        Third law of thermodynamics: The entropy of a system approaches a constant value as the
        temperature approaches zero. The entropy of a system at absolute zero is typically zero, and in
        all cases is determined only by the number of different ground states it has. Specifically, the
        entropy of a pure crystalline substance at absolute zero temperature is zero.

Classical thermodynamics describes the exchange of work and heat between systems. It has a special
interest in systems that are individually in states of thermodynamic equilibrium. Thermodynamic
equilibrium is a condition of systems which are adequately described by only macroscopic variables.
Every physical system, however, when microscopically examined, shows apparently random microscopic
statistical fluctuations in its thermodynamic variables of state (entropy, temperature, pressure, etc.).
These microscopic fluctuations are negligible for systems which are nearly in thermodynamic equilibrium
and which are only macroscopically examined. They become important, however, for systems which are
nearly in thermodynamic equilibrium when they are microscopically examined, and, exceptionally, for
macroscopically examined systems that are in critical states,[7] and for macroscopically examined systems
that are far from thermodynamic equilibrium.

There have been suggestions of additional laws, but none of them achieve the generality of the four
accepted laws, and they are not mentioned in standard textbooks.[1][2][3][4][5][8][9]

The laws of thermodynamics are important fundamental laws in physics and they are applicable in other
natural sciences.



  Table of Contents
    1                                            Zeroth law
    2                                             First law
    3                                           Second law
    4                                             Third law
    5                                              History
    6                                             See also
    7                                           References
    8                                          Further reading

Zeroth law
The zeroth law of thermodynamics may be stated as follows:

If system A and system B are individually in thermal equilibrium with system C, then system A is in
thermal equilibrium with system B

The zeroth law implies that thermal equilibrium, viewed as a binary relation, is a Euclidean relation. If we
assume that the binary relationship is also reflexive, then it follows that thermal equilibrium is an
equivalence relation. Equivalence relations are also transitive and symmetric. The symmetric relationship
allows one to speak of two systems being "in thermal equilibrium with each other", which gives rise to a
simpler statement of the zeroth law:

If two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other

However, this statement requires the implicit assumption of both symmetry and reflexivity, rather than
reflexivity alone.

The law is also a statement about measurability. To this effect the law allows the establishment of an
empirical parameter, the temperature, as a property of a system such that systems in equilibrium with
each other have the same temperature. The notion of transitivity permits a system, for example a gas
thermometer, to be used as a device to measure the temperature of another system.

Although the concept of thermodynamic equilibrium is fundamental to thermodynamics and was clearly
stated in the nineteenth century, the desire to label its statement explicitly as a law was not widely felt
until Fowler and Planck stated it in the 1930s, long after the first, second, and third law were already
widely understood and recognized. Hence it was numbered the zeroth law. The importance of the law as
a foundation to the earlier laws is that it allows the definition of temperature in a non-conjugate variable.




First law
The first law of thermodynamics may be stated thus:

        Increase in internal energy of a body = heat supplied to the body - work done by the body. U = Q
        -W
For a thermodynamic cycle, the net heat supplied to the system equals the net work done by the
        system.

More specifically, the First Law encompasses several principles:

        The law of conservation of energy.

        This states that energy can be neither created nor destroyed. However, energy can change
        forms, and energy can flow from one place to another. The total energy of an isolated system
        remains the same.

        The concept of internal energy and its relationship to temperature.

        If a system, for example a rock, has a definite temperature, then its total energy has three
        distinguishable components. If the rock is flying through the air, it has kinetic energy. If it is high
        above the ground, it has gravitational potential energy. In addition to these, it has internal energy
        which is the sum of the kinetic energy of vibrations of the atoms in the rock, and other sorts of
        microscopic motion, and of the potential energy of interactions between the atoms within the rock.
        Other things being equal, the internal energy increases as the rock's temperature increases. The
        concept of internal energy is the characteristic distinguishing feature of the first law of
        thermodynamics.

        The flow of heat is a form of energy transfer.

        In other words, a quantity of heat that flows from a hot body to a cold one can be expressed as an
        amount of energy being transferred from the hot body to the cold one.

        Performing work is a form of energy transfer.

        For example, when a machine lifts a heavy object upwards, some energy is transferred from the
        machine to the object. The object acquires its energy in the form of gravitational potential energy
        in this example.

Combining these principles leads to one traditional statement of the first law of thermodynamics: it is not
possible to construct a perpetual motion machine which will continuously do work without consuming
energy.


Second law
The second law of thermodynamics asserts the existence of a quantity called the entropy of a system and
further states that

When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium
in itself (but not necessarily in equilibrium with each other at first) are at some time allowed to interact,
breaking the isolation that separates the two systems, allowing them to exchange matter or energy, they
will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated
systems is less than or equal to the entropy of the final combination of exchanging systems. In the
process of reaching a new thermodynamic equilibrium, total entropy has increased, or at least has not
decreased.

It follows that the entropy of an isolated macroscopic system never decreases. The second law states
that spontaneous natural processes increase entropy overall, or in another formulation that heat can
spontaneously be conducted or radiated only from a higher-temperature region to a lower-temperature
region, but not the other way around.

The second law refers to a wide variety of processes, reversible and irreversible. Its main import is to tell
about irreversibility.

The prime example of irreversibility is in the transfer of heat by conduction or radiation. It was known long
before the discovery of the notion of entropy that when two bodies of different temperatures are
connected with each other by purely thermal connection, conductive or radiative, then heat always flows
from the hotter body to the colder one. This fact is part of the basic idea of heat, and is related also to the
so-called zeroth law, though the textbooks' statements of the zeroth law are usually reticent about that,
because they have been influenced by Carathéodory's basing his axiomatics on the law of conservation
of energy and trying to make heat seem a theoretically derivative concept instead of an axiomatically
accepted one. Šilahvý (1997) notes that Carathéodory's approach does not work for the description of
irreversible processes that involve both heat conduction and conversion of kinetic energy into internal
energy by viscosity (which is another prime example of irreversibility), because "the mechanical power
and the rate of heating are not expressible as differential forms in the 'external parameters'". [10]

The second law tells also about kinds of irreversibility other than heat transfer, and the notion of entropy
is needed to provide that wider scope of the law.

According to the second law of thermodynamics, in a reversible heat transfer, an element of heat
transferred, δQ, is the product of the temperature (T), both of the system and of the sources or
destination of the heat, with the increment (dS) of the system's conjugate variable, its entropy (S)

        View formula on Wikipedia[1]

The second law defines entropy, which may be viewed not only as a macroscopic variable of classical
thermodynamics, but may also be viewed as a measure of deficiency of physical information about the
microscopic details of the motion and configuration of the system, given only predictable experimental
reproducibility of bulk or macroscopic behavior as specified by macroscopic variables that allow the
distinction to be made between heat and work. More exactly, the law asserts that for two given
macroscopically specified states of a system, there is a quantity called the difference of entropy between
them. The entropy difference tells how much additional microscopic physical information is needed to
specify one of the macroscopically specified states, given the macroscopic specification of the other,
which is often a conveniently chosen reference state. It is often convenient to presuppose the reference
state and not to explicitly state it. A final condition of a natural process always contains microscopically
specifiable effects which are not fully and exactly predictable from the macroscopic specification of the
initial condition of the process. This is why entropy increases in natural processes. The entropy increase
tells how much extra microscopic information is needed to tell the final macroscopically specified state
from the initial macroscopically specified state.[11]


Third law
The third law of thermodynamics is sometimes stated as follows:

The entropy of a perfect crystal at absolute zero is exactly equal to zero.

At zero temperature the system must be in a state with the minimum thermal energy. This statement
holds true if the perfect crystal has only one state with minimum energy. Entropy is related to the number
of possible microstates according to S = kBln(Ω), where S is the entropy of the system, kB Boltzmann's
constant, and Ω the number of microstates (e.g. possible configurations of atoms). At absolute zero there
is only 1 microstate possible (Ω=1) and ln(1) = 0.
A more general form of the third law that applies to systems such as glasses that may have more than
one minimum energy state:

The entropy of a system approaches a constant value as the temperature approaches zero.

The constant value (not necessarily zero) is called the residual entropy of the system.

History

See also: Philosophy of thermal and statistical physics

Count Rumford (born Benjamin Thompson) showed, about 1797, that mechanical action can generate
indefinitely large amounts of heat, so challenging the caloric theory. The historically first established
thermodynamic principle which eventually became the second law of thermodynamics was formulated by
Sadi Carnot during 1824. By 1860, as formalized in the works of those such as Rudolf Clausius and
William Thomson, two established principles of thermodynamics had evolved, the first principle and the
second principle, later restated as thermodynamic laws. By 1873, for example, thermodynamicist Josiah
Willard Gibbs, in his memoir Graphical Methods in the Thermodynamics of Fluids, clearly stated the first
two absolute laws of thermodynamics. Some textbooks throughout the 20th century have numbered the
laws differently. In some fields removed from chemistry, the second law was considered to deal with the
efficiency of heat engines only, whereas what was called the third law dealt with entropy increases.
Directly defining zero points for entropy calculations was not considered to be a law. Gradually, this
separation was combined into the second law and the modern third law was widely adopted.




                           ENERGY TRASFORMATION
                            Laws of Thermodynamics

 Process functions:
 Work · Heat

 Material properties

                                                                  T
                                     Specific heat capacity c =
                                                                  N

                                     Compressibility        β=−1
V ∂p

                                                                 1
                                   Thermal expansion     α=
                                                                 V


  · Free entropy



                                  Internal energy       U(S,V)

                                  Enthalpy              H(S,p) = U + pV

                                  Helmholtz free energy A(T,V) = U − TS

                                  Gibbs free energy     G(T,p) = H − TS




The four laws of thermodynamics define fundamental physical quantities (temperature, energy, and
entropy) that characterize thermodynamic systems. The laws describe how these quantities behave
under various circumstances, and forbid certain phenomena (such as perpetual motion).

The four laws of thermodynamics are:1][2][3][4][5][6]

Zeroth law of thermodynamics: If two systems are in thermal equilibrium with a third system, they must
be in thermal equilibrium with each other. This law helps define the notion of temperature.

First law of thermodynamics: Heat and work are forms of energy transfer. Energy is invariably conserved
but the internal energy of a closed system changes as heat and work are transferred in or out of it.
Equivalently, perpetual motion machines of the first kind are impossible.

Second law of thermodynamics: The entropy of any isolated system not in thermal equilibrium almost
always increases. Isolated systems spontaneously evolve towards thermal equilibrium—the state of
maximum entropy of the system—in a process known as "thermalization". Equivalently, perpetual
motion machines of the second kind are impossible.

Third law of thermodynamics: The entropy of a system approaches a constant value as the temperature
approaches zero. The entropy of a system at absolute zero is typically zero, and in all cases is
determined only by the number of different ground states it has. Specifically, the entropy of a pure
crystalline substance at absolute zero temperature is zero.

Classical thermodynamics describes the exchange of work and heat between systems. It has a special
interest in systems that are individually in states of thermodynamic equilibrium. Thermodynamic
equilibrium is a condition of systems which are adequately described by only macroscopic variables.
Every physical system, however, when microscopically examined, shows apparently random microscopic
statistical fluctuations in its thermodynamic variables of state (entropy, temperature, pressure, etc.).
These microscopic fluctuations are negligible for systems which are nearly in thermodynamic
equilibrium and which are only macroscopically examined. They become important, however, for
systems which are nearly in thermodynamic equilibrium when they are microscopically examined, and,
exceptionally, for macroscopically examined systems that are in critical states,[7] and for
macroscopically examined systems that are far from thermodynamic equilibrium.

There have been suggestions of additional laws, but none of them achieve the generality of the four
accepted laws, and they are not mentioned in standard textbooks.[1][2][3][4][5][8][9]

The laws of thermodynamics are important fundamental laws in physics and they are applicable in other
natural sciences.




Zeroth law

The zeroth law of thermodynamics may be stated as follows:

If system A and system B are individually in thermal equilibrium with system C, then system A is in
thermal equilibrium with system B

The zeroth law implies that thermal equilibrium, viewed as a binary relation, is a Euclidean relation. If
we assume that the binary relationship is also reflexive, then it follows that thermal equilibrium is an
equivalence relation. Equivalence relations are also transitive and symmetric. The symmetric
relationship allows one to speak of two systems being "in thermal equilibrium with each other", which
gives rise to a simpler statement of the zeroth law:

If two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other

However, this statement requires the implicit assumption of both symmetry and reflexivity, rather than
reflexivity alone.

The law is also a statement about measurability. To this effect the law allows the establishment of an
empirical parameter, the temperature, as a property of a system such that systems in equilibrium with
each other have the same temperature. The notion of transitivity permits a system, for example a gas
thermometer, to be used as a device to measure the temperature of another system.

Although the concept of thermodynamic equilibrium is fundamental to thermodynamics and was clearly
stated in the nineteenth century, the desire to label its statement explicitly as a law was not widely felt
until Fowler and Planck stated it in the 1930s, long after the first, second, and third law were already
widely understood and recognized. Hence it was numbered the zeroth law. The importance of the law as
a foundation to the earlier laws is that it allows the definition of temperature in a non-circular way
without reference to entropy, its conjugate variable.

First law

The first law of thermodynamics may be stated thus:

Increase in internal energy of a body = heat supplied to the body - work done by the body. U = Q - W

For a thermodynamic cycle, the net heat supplied to the system equals the net work done by the
system.

More specifically, the First Law encompasses several principles:

The law of conservation of energy.

This states that energy can be neither created nor destroyed. However, energy can change forms, and
energy can flow from one place to another. The total energy of an isolated system remains the same.

The concept of internal energy and its relationship to temperature.

If a system, for example a rock, has a definite temperature, then its total energy has three
distinguishable components. If the rock is flying through the air, it has kinetic energy. If it is high above
the ground, it has gravitational potential energy. In addition to these, it has internal energy which is the
sum of the kinetic energy of vibrations of the atoms in the rock, and other sorts of microscopic motion,
and of the potential energy of interactions between the atoms within the rock. Other things being equal,
the internal energy increases as the rock's temperature increases. The concept of internal energy is the
characteristic distinguishing feature of the first law of thermodynamics.

The flow of heat is a form of energy transfer.

In other words, a quantity of heat that flows from a hot body to a cold one can be expressed as an
amount of energy being transferred from the hot body to the cold one.

Performing work is a form of energy transfer.

For example, when a machine lifts a heavy object upwards, some energy is transferred from the
machine to the object. The object acquires its energy in the form of gravitational potential energy in this
example.

Combining these principles leads to one traditional statement of the first law of thermodynamics: it is
not possible to construct a perpetual motion machine which will continuously do work without
consuming energy.

Second law
The second law of thermodynamics asserts the existence of a quantity called the entropy of a system
and further states that

When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium
in itself (but not necessarily in equilibrium with each other at first) are at some time allowed to interact,
breaking the isolation that separates the two systems, allowing them to exchange matter or energy,
they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial,
isolated systems is less than or equal to the entropy of the final combination of exchanging systems. In
the process of reaching a new thermodynamic equilibrium, total entropy has increased, or at least has
not decreased.

It follows that the entropy of an isolated macroscopic system never decreases. The second law states
that spontaneous natural processes increase entropy overall, or in another formulation that heat can
spontaneously be conducted or radiated only from a higher-temperature region to a lower-temperature
region, but not the other way around.

The second law refers to a wide variety of processes, reversible and irreversible. Its main import is to tell
about irreversibility.

The prime example of irreversibility is in the transfer of heat by conduction or radiation. It was known
long before the discovery of the notion of entropy that when two bodies of different temperatures are
connected with each other by purely thermal connection, conductive or radiative, then heat always
flows from the hotter body to the colder one. This fact is part of the basic idea of heat, and is related
also to the so-called zeroth law, though the textbooks' statements of the zeroth law are usually reticent
about that, because they have been influenced by Carathéodory's basing his axiomatics on the law of
conservation of energy and trying to make heat seem a theoretically derivative concept instead of an
axiomatically accepted one. Šilahvý (1997) notes that Carathéodory's approach does not work for the
description of irreversible processes that involve both heat conduction and conversion of kinetic energy
into internal energy by viscosity (which is another prime example of irreversibility), because "the
mechanical power and the rate of heating are not expressible as differential forms in the 'external
parameters'".[10]

The second law tells also about kinds of irreversibility other than heat transfer, and the notion of
entropy is needed to provide that wider scope of the law.

According to the second law of thermodynamics, in a reversible heat transfer, an element of heat
transferred, δQ, is the product of the temperature (T), both of the system and of the sources or
destination of the heat, with the increment (dS) of the system's conjugate variable, its entropy (S)

View formula on Wikipedia[1]

The second law defines entropy, which may be viewed not only as a macroscopic variable of classical
thermodynamics, but may also be viewed as a measure of deficiency of physical information about the
microscopic details of the motion and configuration of the system, given only predictable experimental
reproducibility of bulk or macroscopic behavior as specified by macroscopic variables that allow the
distinction to be made between heat and work. More exactly, the law asserts that for two given
macroscopically specified states of a system, there is a quantity called the difference of entropy
between them. The entropy difference tells how much additional microscopic physical information is
needed to specify one of the macroscopically specified states, given the macroscopic specification of the
other, which is often a conveniently chosen reference state. It is often convenient to presuppose the
reference state and not to explicitly state it. A final condition of a natural process always contains
microscopically specifiable effects which are not fully and exactly predictable from the macroscopic
specification of the initial condition of the process. This is why entropy increases in natural processes.
The entropy increase tells how much extra microscopic information is needed to tell the final
macroscopically specified state from the initial macroscopically specified state.[11]

Third law

The third law of thermodynamics is sometimes stated as follows:

The entropy of a perfect crystal at absolute zero is exactly equal to zero.

At zero temperature the system must be in a state with the minimum thermal energy. This statement
holds true if the perfect crystal has only one state with minimum energy. Entropy is related to the
number of possible microstates according to S = kBln(Ω), where S is the entropy of the system, kB
Boltzmann's constant, and Ω the number of microstates (e.g. possible configurations of atoms). At
absolute zero there is only 1 microstate possible (Ω=1) and ln(1) = 0.

A more general form of the third law that applies to systems such as glasses that may have more than
one minimum energy state:

The entropy of a system approaches a constant value as the temperature approaches zero.

The constant value (not necessarily zero) is called the residual entropy of the system.

History

See also: Philosophy of thermal and statistical physics

Count Rumford (born Benjamin Thompson) showed, about 1797, that mechanical action can generate
indefinitely large amounts of heat, so challenging the caloric theory. The historically first established
thermodynamic principle which eventually became the second law of thermodynamics was formulated
by Sadi Carnot during 1824. By 1860, as formalized in the works of those such as Rudolf Clausius and
William Thomson, two established principles of thermodynamics had evolved, the first principle and the
second principle, later restated as thermodynamic laws. By 1873, for example, thermodynamicist Josiah
Willard Gibbs, in his memoir Graphical Methods in the Thermodynamics of Fluids, clearly stated the first
two absolute laws of thermodynamics. Some textbooks throughout the 20th century have numbered
the laws differently. In some fields removed from chemistry, the second law was considered to deal with
the efficiency of heat engines only, whereas what was called the third law dealt with entropy increases.
Directly defining zero points for entropy calculations was not considered to be a law. Gradually, this
separation was combined into the second law and the modern third law was widely adopted.

See also

Conservation law

Third law of thermodynamics

Entropy production

Heat death of the universe

Laws of science

Table of thermodynamic equations

Ginsberg's Theorem

References

↑ 1.0 1.1 1.2 Guggenheim, E.A. (1985). Thermodynamics. An Advanced Treatment for Chemists and
Physicists, seventh edition, North Holland, Amsterdam, ISBN 0-444-86951-4.

↑ 2.0 2.1 Kittel, C. Kroemer, H. (1980). Thermal Physics, second edition, W.H. Freeman, San Francisco,
ISBN 0-7167-1088-9.

↑ 3.0 3.1 Adkins, C.J. (1968). Equilibrium Thermodynamics, McGraw-Hill, London, ISBN 0-07-084057-1.

↑ 4.0 4.1 Kondepudi D. (2008). Introduction to Modern Thermodynamics, Wiley, Chichester, ISBN 978-
0-470-01598-8.

↑ 5.0 5.1 Lebon, G., Jou, D., Casas-Vázquez, J. (2008). Understanding Non-equilibrium Thermodynamics.
Foundations, Applications, Frontiers, Springer, Berlin, ISBN 978-3-540-74252-4.

↑ Chris Vuille; Serway, Raymond A.; Faughn, Jerry S. (2009). College physics. Belmont, CA: Brooks/Cole,
Cengage Learning. p. 355. ISBN 0-495-38693-6.
http://books.google.ca/books?id=CX0u0mIOZ44C&pg=PT355.

↑ Balescu, R. (1975). Equilibrium and Nonequilibrium Statistical Mechanics, Wiley, New York, ISBN 0-
471-04600-0.

↑ De Groot, S.R., Mazur, P. (1962). Non-equilibrium Thermodynamics, North Holland, Amsterdam.

↑ Glansdorff, P., Prigogine, I. (1971). Thermodynamic Theory of Structure, Stability and Fluctuations,
Wiley-Interscience, London, ISBN 0-471-30280-5.
↑ Šilhavý, M. (1997). The Mechanics and Thermodynamics of Continuous Media, Springer, Berlin, ISBN
3-540-58378-5, page 137.

↑ Ben-Naim, A. (2008). A Farewell to Entropy: Statistical Thermodynamics Based on Information, World
Scientific, New Jersey, ISBN 978-981-270-706-2.

Further reading

Atkins, Peter, 2007. Four Laws That Drive the Universe. OUP Oxford.

Goldstein, Martin, and Inge F., 1993. The Refrigerator and the Universe. Harvard Univ. Press. A gentle
introduction.ar:‫ال حراري ة ال دي نام ي كا ق وان ين‬

ca:Lleis de la termodinàmica cs:Termodynamický zákon de:Thermodynamik#Kurze Zusammenfassung
der Hauptsätze fa:‫ ت رمودي نام يک ق وان ين‬fr:Principes de la thermodynamique gl:Leis da termodinámica
ko:열역학 법칙 id:Hukum termodinamika lt:Termodinamikos dėsniai
ml:                                 ms:Hukum termodinamik nl:Hoofdwetten van de
thermodynamica ro:Principiile termodinamicii ru:Начала термодинамики sl:Zakoni termodinamike
fi:Termodynamiikan pääsäännöt sv:Termodynamikens huvudsatser th:
tr:Termodinamik kanunları uk:Закони термодинаміки

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Appl Microbiol. 1963 November; 11(6): 523–528.

PMCID: PMC1058043

Microbiological Production of Gibberellic Acid in Glucose Media1

A. Sanchez-Marroquin

Escuela Nacional de Ciencias Quimícas, Universidad de México, Mexico, D.F., Mexico

1This paper was presented at the II Latin-American Congress of Microbiology, San José, Costa Rica, 10-
16 December 1961.

Author information ► Copyright and License information ►

Copyright notice

Abstract

Gibberellic acid production from various substrates was studied in 43 strains of Fusarium, among which
F. moniliforme strain IOC-3326 was selected as the best producer. Experiments were carried out in
shaker flasks and pilot plant fermentors. The results indicate that the best substrate for gibberellic acid
production with this strain is composed of the following: glucose, 20 g; corn steep liquor, 25 g;
ammonium nitrate, 2.6 g; monopotassium phosphate, 0.5 g; potassium sulfate, 0.2 g; and water, 1000
ml. Glucose, ammonium nitrate, and corn steep liquor were found to be critical. With this medium,
maximal yields of 1196 mg per liter in shaker flasks and 997 mg per liter in fermentors were produced.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the
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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

Bird HL, Pugh CT. A Paper Chromatographic Separation of Gibberellic Acid and Gibberellin A. Plant
Physiol. 1958 Jan;33(1):45–46. [PMC free article] [PubMed]

DARKEN MA, JENSEN AL, SHU P. Production of gibberellic acid by fermentation. Appl Microbiol. 1959
Sep;7:301–303. [PMC free article] [PubMed]

STODOLA FH, RAPER KB, FENNELL DI, CONWAY HF, SOHNS VE, LANGFORD CT, JACKSON RW. The
microbiological production of gibberellins A and X. Arch Biochem Biophys. 1955 Jan;54(1):240–245.
[PubMed]



Articles from Applied Microbiology are provided here courtesy of American Society for Microbiology
(ASM)

Formats:

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Related citations in PubMed

Gibberellic acid production by Fusarium moniliforme on lupin seed extract. [Acta Microbiol Pol. 1994]

Gibberellic acid production by Fusarium moniliforme on lupin seed extract.

Gulewicz K, Rataj-Guranowska M, Lukaszewska N, Michalski Z. Acta Microbiol Pol. 1994; 43(1):73-7.

Survey of some Fusarium moniliforme strains from different host plants for compounds possessing
gibberellin-like activity. [Zentralbl Bakteriol Parasitenkd Infektionsk...]
Survey of some Fusarium moniliforme strains from different host plants for compounds possessing
gibberellin-like activity.

El-Bahrawi S. Zentralbl Bakteriol Parasitenkd Infektionskr Hyg. 1977; 132(2):178-83.

Biosynthesis of gibberellic acid from milk permeate in repeated batch operation by a mutant Fusarium
moniliforme cells immobilized on loofa sponge. [Bioresour Technol. 2009]

Biosynthesis of gibberellic acid from milk permeate in repeated batch operation by a mutant Fusarium
moniliforme cells immobilized on loofa sponge.

Meleigy SA, Khalaf MA. Bioresour Technol. 2009 Jan; 100(1):374-9. Epub 2008 Aug 5.

Morphological mutants of Gibberella fujikuroi for enhanced production of gibberellic acid. [J Appl
Microbiol. 2006]

Morphological mutants of Gibberella fujikuroi for enhanced production of gibberellic acid.

Lale G, Jogdand VV, Gadre RV. J Appl Microbiol. 2006; 100(1):65-72.

EFFECTS OF CORN STEEP LIQUOR AND THIAMINE ON L-GLUTAMIC ACID FERMENTATION OF
HYDROCARBONS.IV. UTILIZATION OF HYDROCARBONS BY MICROORGANISMS. [Appl Microbiol. 1965]

EFFECTS OF CORN STEEP LIQUOR AND THIAMINE ON L-GLUTAMIC ACID FERMENTATION OF
HYDROCARBONS.IV. UTILIZATION OF HYDROCARBONS BY MICROORGANISMS.

TAKAHASHI J, KOBAYASHI K, IMADA Y, YAMADA K. Appl Microbiol. 1965 Jan; 13:1-4.

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Home > List of Issues > Table of Contents > Evaluation of Some Food Industry Wastes for Production of
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Environmental Technology

Volume 18, Issue 5, 1997
Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source

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DOI:

          10.1080/09593331808616569

N. Cihangir & N. Aksöza

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Abstract

The control of environmental pollution and the recovery of agricultural, industrial and municipal
wastes by converting them into useful products are two relevant biotechnological goals. In this
study, the possibility of utilising food industry waste and residues as sources of carbon for
gibberellic acid production by Aspergillus niger was investigated. Media prepared from
molasses, vinasse, whey, sugar-beet waste and fruit pomace were used and GA3 yields were
found in concentrations 155, 136.57, 120, 73, 118.13 mg l−1 respectively in such media. It was
observed that food industry wastes can be used and evaluated as cheap sources of carbon for
gibberellic acid production.

          Download full text

Keywords

          food industry wastes,
          evaluation,
          production,
gibberellic acid

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Environmental Technology

Volume 18, Issue 5, 1997




Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source

Preview

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DOI:

          10.1080/09593331808616569

N. Cihangir & N. Aksöza

pages 533-537


Publishing models and article dates explained
Version of record first published: 11 May 2010

Article Views: 13
Alert me

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Abstract

The control of environmental pollution and the recovery of agricultural, industrial and municipal
wastes by converting them into useful products are two relevant biotechnological goals. In this
study, the possibility of utilising food industry waste and residues as sources of carbon for
gibberellic acid production by Aspergillus niger was investigated. Media prepared from
molasses, vinasse, whey, sugar-beet waste and fruit pomace were used and GA3 yields were
found in concentrations 155, 136.57, 120, 73, 118.13 mg l−1 respectively in such media. It was
observed that food industry wastes can be used and evaluated as cheap sources of carbon for
gibberellic acid production.

          Download full text

Keywords

          food industry wastes,
          evaluation,
          production,
          gibberellic acid

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Environmental Technology

Volume 18, Issue 5, 1997




Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source

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DOI:

          10.1080/09593331808616569

N. Cihangir & N. Aksöza

pages 533-537


Publishing models and article dates explained
Version of record first published: 11 May 2010

Article Views: 13

Alert me

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Abstract

The control of environmental pollution and the recovery of agricultural, industrial and municipal
wastes by converting them into useful products are two relevant biotechnological goals. In this
study, the possibility of utilising food industry waste and residues as sources of carbon for
gibberellic acid production by Aspergillus niger was investigated. Media prepared from
molasses, vinasse, whey, sugar-beet waste and fruit pomace were used and GA3 yields were
found in concentrations 155, 136.57, 120, 73, 118.13 mg l−1 respectively in such media. It was
observed that food industry wastes can be used and evaluated as cheap sources of carbon for
gibberellic acid production.

          Download full text

Keywords

          food industry wastes,
          evaluation,
          production,
          gibberellic acid

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Gibberellic acid

From Wikipedia, the free encyclopedia

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           This article needs additional citations for verification. Please help improve this article by
           adding citations to reliable sources. Unsourced material may be challenged and removed.
           (November 2012)



                      Gibberellic acid
IUPAC name[show]




                       Identifiers


CAS number             77-06-5


PubChem                522636


ChemSpider             7995349


UNII                   BU0A7MWB6L


EC number              201-001-0


KEGG                   C01699


ChEBI                  CHEBI:28833


ChEMBL                 CHEMBL566653


Jmol-3D images         Image 1


                        SMILES

[show]




                         InChI

[show]




                       Properties


Molecular formula      C19H22O6
Molar mass                  346.37 g/mol


  Melting point               233 - 235 °C (decomposition)

  Solubility in water         5 g/l (20 °C)


                               Hazards


  EU classification           Irritant (Xi)


  R-phrases                   R36


  S-phrases                   R26, S36


                         (verify) (what is:   / ?)
   Except where noted otherwise, data are given for materials
              in their standard state (at 25 °C, 100 kPa)


                         Infobox references


Gibberellic acid (also called Gibberellin A3, GA, and GA3) is a hormone found in plants. Its
chemical formula is C19H22O6. When purified, it is a white to pale-yellow solid.

Gibberellic acid is a simple gibberellin, a pentacyclic diterpene acid promoting growth and
elongation of cells. It affects decomposition of plants and helps plants grow if used in small
amounts, but eventually plants develop tolerance to it[citation needed]. GA stimulates the cells of
germinating seeds to produce mRNA molecules that code for hydrolytic enzymes. Gibberellic
acid is a very potent hormone whose natural occurrence in plants controls their development.
Since GA regulates growth, applications of very low concentrations can have a profound effect
while too much will have the opposite effect.[1] It is usually used in concentrations between 0.01
and 10 mg/L.

GA was first identified in Japan in 1935, as a metabolic byproduct of the plant pathogen
Gibberella fujikuroi (thus the name), which afflicts rice plants; fujikuroi-infected plants develop
bakanae ("foolish seedling"), which causes them to grow so much taller than normal that they
die from no longer being sturdy enough to support their own weight.

Gibberellins have a number of effects on plant development. They can stimulate rapid stem and
root growth, induce mitotic division in the leaves of some plants, and increase seed germination
rate.
Gibberellic acid is sometimes used in laboratory and greenhouse settings to trigger germination
in seeds that would otherwise remain dormant.[1] It is also widely used in the grape-growing
industry as a hormone to induce the production of larger bundles and bigger grapes, especially
Thompson seedless grapes. In the Okanagan and Creston valleys, it is also used as a growth
replicator in the cherry industry.

[edit] See also

       Gibberellin
       Plant hormone
       6-Benzylaminopurine

[edit] References

   1. ^ a b Riley, John M.. "Gibberellic Acid for Fruit Set and Seed Germination".
      http://www.crfg.org/tidbits/gibberellic.html. Retrieved 26 Oct 2012.

[edit] External links

       No longer maintained. Safety MSDS data
       Synonyms at webbook.nist.gov
       www.crfg.org

Retrieved from "http://en.wikipedia.org/w/index.php?title=Gibberellic_acid&oldid=535424207"
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Krishna

  • 1.
    Law s oftherm Submit Search Powered by JRank Biology Reference Biology » Re-Se » Secondary Metabolites in Plants - Biology Encyclopedia Secondary Metabolites in Plants Ads by Google Leica Super-Resolution - The Greatest Confocal Resolution With the New Leica TCS SP8 STED. - www.Leica-Microsystems.com/SP8 IGS N2 & O2 Plants - Worldwide supply of Nitrogen and Oxygen Generators - www.igs- italia.com Cyclodextrins - 1st time in India DMF available - www.cyclodextrin.com
  • 2.
    Photo by: pashabo Adsby Google Medicinal Chemistry Journal Publish Your Research Article In International Journal:IOSR JOURNALS iosrjournals.org Enzyme Manufacturer Food processing Now in India! www.KenEncoreGroup.com Secondary metabolites are chemicals produced by plants for which no role has yet been found in growth, photosynthesis, reproduction, or other "primary" functions. These chemicals are extremely diverse; many thousands have been identified in several major classes. Each plant family, genus, and species produces a characteristic mix of these chemicals, and they can sometimes be used as taxonomic characters in classifying plants. Humans use some of these compounds as medicines, flavorings, or recreational drugs.
  • 3.
    Secondary metabolites canbe classified on the basis of chemical structure (for example, having rings, containing a sugar), composition (containing nitrogen or not), their solubility in various solvents, or the pathway by which they are synthesized (e.g., phenylpropanoid, which produces tannins). A simple classification includes three main groups: the terpenes (made from mevalonic acid, composed almost entirely of carbon and hydrogen), phenolics (made from simple sugars, containing benzene rings, hydrogen, and oxygen), and nitrogen-containing compounds (extremely diverse, may also contain sulfur). The apparent lack of primary function in the plant, combined with the observation that many secondary metabolites have specific negative impacts on other organisms such as herbivores and pathogens , leads to the hypothesis that they have evolved because of their protective value. Many secondary metabolites are toxic or repellant to herbivores and microbes and help defend plants producing them. Production increases when a plant is attacked by herbivores or pathogens. Some compounds are released into the air when plants are attacked by insects; these compounds attract parasites and predators that kill the herbivores. Recent research is identifying more and more primary roles for these chemicals in plants as signals, antioxidants , and other functions, so "secondary" may not be an accurate description in the future. Consuming some secondary metabolites can have severe consequences. Alkaloids can block ion channels, inhibit enzymes , or interfere with neurotransmission, producing hallucinations , loss of coordination, convulsions, vomiting, and death. Some phenolics interfere with digestion, slow growth, block enzyme activity and cell division, or just taste awful. Most herbivores and plant pathogens possess mechanisms that ameliorate the impacts of plant metabolites, leading to evolutionary associations between particular groups of pests and plants. Some herbivores (for example, the monarch butterfly) can store (sequester) plant toxins and gain protection against their enemies. Secondary metabolites may also inhibit the growth of competitor plants (allelopathy). Pigments (such as terpenoid carotenes, phenolics, and flavonoids) color flowers and, together with terpene and phenolic odors, attract pollinators.
  • 4.
    Secondary chemicals areimportant in plant use by humans. Most pharmaceuticals are based on plant chemical structures, and secondary metabolites are widely used for recreation and stimulation (the alkaloids nicotine and cocaine; the terpene cannabinol). The study of such plant use is called ethnopharmacology. Psychoactive plant chemicals are central to some religions, and flavors of secondary compounds shape our food preferences. The characteristic flavors and aroma of cabbage and relatives are caused by Class Example Example Some Effects and Uses Compounds Sources NITROGEN- CONTAINING Alkaloids nicotine cocaine tobacco coca plant interfere with theobromine chocolate (cocao) neurotransmission, block
  • 5.
    Class Example Example Some Effects and Uses Compounds Sources enzyme action NITROGEN-AND SULFUR- CONTAINING Glucosinolates sinigrin cabbage, relatives TERPENOIDS Monoterpenes menthol linalool mint and relatives, interfere with many plants neurotransmission, block ion transport, anesthetic Sesquiterpenes parthenolid Parthenium and contact dermatitis relatives ( Asteraceae ) Diterpenes gossypol cotton block phosphorylation; toxic Triterpenes, cardiac digitogenin Digitalis (foxglove) stimulate heart muscle, alter glycosides ion transport Tetraterpenoids carotene many plants antioxidant; orange coloring Terpene polymers rubber Hevea (rubber) gum up insects; airplane tires trees, dandelion Sterols spinasterol spinach interfere with animal hormone action PHENOLICS
  • 6.
    Class Example Example Some Effects and Uses Compounds Sources Phenolic acids caffeic, all plants cause oxidative damage, chlorogenic browning in fruits and wine Coumarins umbelliferone carrots, parsnip cross-link DNA, block cell division Lignans podophyllin mayapple poison cathartic, vomiting, allergic urushiol ivy dermatitis Flavonoids anthocyanin, almost all plants flower, leaf color; inhibit catechin enzymes, anti- and pro- oxidants, estrogenic Tannins gallotannin, oak, hemlock trees, bind to proteins, enzymes, condensed birdsfoot trefoil, block digestion, antioxidants tannin legumes Lignin lignin all land plants structure, toughness, fiber nitrogen-and sulfur-containing chemicals, glucosinolates, which protect these plants from many enemies. The astringency of wine and chocolate derives from tannins. The use of spices and other seasonings developed from their combined uses as preservatives (since they are antibiotic) and flavorings. SEE ALSO Flowers ; Herbivory and Plant Defenses ; Metabolism, Cellular ; Poisons Jack Schultz Bibliography
  • 7.
    Agosta, William. BombardierBeetles and Fever Trees: A Close-up Look at Chemical Warfare and Signals in Animals and Plants. Reading, MA: Addison-Wesley, 1996. Bidlack, Wayne R. Phytochemicals as Bioactive Agents. Lancaster, PA: Technomic Publishers, 2000. Karban, Richard, and Ian T. Baldwin. Induced Responses to Herbivory. Chicago: University of Chicago Press, 1997. Rosenthal, Gerald A., and May R. Berenbaum. Herbivores, Their Interactions with Secondary Plant Metabolites. San Diego, CA: Academic Press, 1991. Ads by Google Chemical Crystallography - Inexpensive benchtop XRD system to determine small molecule structure - www.rigaku.com User Contributions: 1 aarcee varte Mar 4, 2008 @ 11:23 pm please explain how 2 extract secondary metabolites which is not secreted out from plants and remain inside the plants only Comment about this article, ask questions, or add new information about this topic: Name:
  • 8.
    E-mail: Show my email publicly Type the code shown: Public Comment: (50-4000 characters) Send Secondary Metabolites in Plants - Biology Encyclopedia forum « Science Writer Seed Germination and Dormancy » Copyright © 2013 Advameg, Inc. Read more: http://www.biologyreference.com/Re-Se/Secondary-Metabolites-in- Plants.html#ixzz2IdgaAPMf Cellulose From Wikipedia, the free encyclopedia
  • 9.
    Jump to: navigation,search Cellulose[1] Identifiers CAS number 9004-34-6 UNII SMD1X3XO9M EC-number 232-674-9 ChEMBL CHEMBL1201676 Properties Molecular formula (C6H10O5)n Appearance white powder Density 1.5 g/cm3 Melting point decomp. Solubility in water none
  • 10.
    Hazards EUIndex not listed NFPA 704 1 1 0 Related compounds Related compounds Starch (verify) (what is: / ?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references Cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units.[2][3] Cellulose is the structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most common organic compound on Earth. About 33% of all plant matter is cellulose (the cellulose content of cotton fiber is 90%, that of wood is 40–50% and that of dried hemp is approximately 75%).[4][5][6] For industrial use, cellulose today is mainly obtained from wood pulp and cotton. Cellulose is mainly used to produce paperboard and paper; to a smaller extent it is converted into a wide variety of derivative products such as cellophane and rayon. Converting cellulose from energy crops into biofuels such as cellulosic ethanol is under investigation as an alternative fuel source. Some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts. Humans can digest cellulose to some
  • 11.
    extent,[7][8] however itmainly acts as a hydrophilic bulking agent for feces and is often referred to as "dietary fiber". Contents 1 History 2 Products o 2.1 Cellulose source and energy crops 3 Structure and properties 4 Assaying a cellulose-containing material 5 Biosynthesis 6 Breakdown (cellulolysis) 7 Hemicellulose 8 Derivatives 9 References 10 External links [edit] History Cellulose was discovered in 1838 by the French chemist Anselme Payen, who isolated it from plant matter and determined its chemical formula.[2][9][10] Cellulose was used to produce the first successful thermoplastic polymer, celluloid, by Hyatt Manufacturing Company in 1870. Hermann Staudinger determined the polymer structure of cellulose in 1920. The compound was first chemically synthesized (without the use of any biologically derived enzymes) in 1992, by Kobayashi and Shoda.[11] Cellulose in a plant cell. [edit] Products
  • 12.
    Cotton fibres representthe purest natural form of cellulose, containing more than 90% of this carbohydrate. See also: dissolving pulp and pulp (paper) The kraft process is used to separate cellulose from lignin, another major component of plant matter. Cellulose is the major constituent of paper, paperboard, and card stock and of textiles made from cotton, linen, and other plant fibers. Cellulose can be converted into cellophane, a thin transparent film, and into rayon, an important fiber that has been used for textiles since the beginning of the 20th century. Both cellophane and rayon are known as "regenerated cellulose fibers"; they are identical to cellulose in chemical structure and are usually made from dissolving pulp via viscose. A more recent and environmentally friendly method to produce a form of rayon is the Lyocell process. Cellulose is the raw material in the manufacture of nitrocellulose (cellulose nitrate) which is used in smokeless gunpowder and as the base material for celluloid used for photographic and movie films until the mid 1930s. Cellulose is used to make water-soluble adhesives and binders such as methyl cellulose and carboxymethyl cellulose which are used in wallpaper paste. Microcrystalline cellulose (E460i) and powdered cellulose (E460ii) are used as inactive fillers in tablets[12] and as thickeners and stabilizers in processed foods. Cellulose powder is for example used in Kraft's Parmesan cheese to prevent caking inside the tube. Cellulose is used in the laboratory as the stationary phase for thin layer chromatography. Cellulose fibers are also used in liquid filtration, sometimes in combination with diatomaceous earth or other filtration media, to create a filter bed of inert material. Cellulose is further used to make hydrophilic and highly absorbent sponges. Cellulose insulation made from recycled paper is becoming popular as an environmentally preferable material for building insulation. It can be treated with boric acid as a fire retardant. Cellulose consists of crystalline and amorphous regions. By treating it with strong acid, the amorphous regions can be broken up, thereby producing nanocrystalline cellulose, a novel material with many desirable properties.[13] Recently, nanocrystalline cellulose was used as the
  • 13.
    filler phase inbio-based polymer matrices to produce nanocomposites with superior thermal and mechanical properties. [14] [edit] Cellulose source and energy crops Main article: Energy crop The major combustible component of non-food energy crops is cellulose, with lignin second. Non-food energy crops are more efficient than edible energy crops (which have a large starch component), but still compete with food crops for agricultural land and water resources.[15] Typical non-food energy crops include industrial hemp (though outlawed in some countries), switchgrass, Miscanthus, Salix (willow), and Populus (poplar) species. Some bacteria can convert cellulose into ethanol which can then be used as a fuel; see cellulosic ethanol. A strand of cellulose (conformation Iα), showing the hydrogen bonds (dashed) within and between cellulose molecules. [edit] Structure and properties Cellulose has no taste, is odorless, is hydrophilic with the contact angle of 20–30,[16] is insoluble in water and most organic solvents, is chiral and is biodegradable. It can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature. Cellulose is derived from D-glucose units, which condense through β(1→4)-glycosidic bonds. This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch, glycogen, and other carbohydrates. Cellulose is a straight chain polymer: unlike starch, no coiling or branching occurs, and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues. The multiple hydroxyl groups on the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a neighbor chain, holding the chains firmly together side-by-side and forming microfibrils with
  • 14.
    high tensile strength.This strength is important in cell walls, where the microfibrils are meshed into a carbohydrate matrix, conferring rigidity to plant cells. A triple strand of cellulose showing the hydrogen bonds (cyan lines) between glucose strands Compared to starch, cellulose is also much more crystalline. Whereas starch undergoes a crystalline to amorphous transition when heated beyond 60–70 °C in water (as in cooking), cellulose requires a temperature of 320 °C and pressure of 25 MPa to become amorphous in water.[17] Several different crystalline structures of cellulose are known, corresponding to the location of hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures Iα and Iβ. Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II. The conversion of cellulose I to cellulose II is irreversible, suggesting that cellulose I is metastable and cellulose II is stable. With various chemical treatments it is possible to produce the structures cellulose III and cellulose IV.[18] Many properties of cellulose depend on its chain length or degree of polymerization, the number of glucose units that make up one polymer molecule. Cellulose from wood pulp has typical chain lengths between 300 and 1700 units; cotton and other plant fibers as well as bacterial cellulose have chain lengths ranging from 800 to 10,000 units.[11] Molecules with very small chain length resulting from the breakdown of cellulose are known as cellodextrins; in contrast to long-chain cellulose, cellodextrins are typically soluble in water and organic solvents. Plant-derived cellulose is usually found in a mixture with hemicellulose, lignin, pectin and other substances, while microbial cellulose is quite pure, has a much higher water content, and consists of long chains. Cellulose is soluble in cupriethylenediamine (CED), cadmiumethylenediamine (Cadoxen), N- methylmorpholine N-oxide and lithium chloride / dimethylformamide.[19] This is used in the production of regenerated celluloses (such as viscose and cellophane) from dissolving pulp. [edit] Assaying a cellulose-containing material Given a cellulose-containing material, the carbohydrate portion that does not dissolve in a 17.5% solution of sodium hydroxide at 20 °C is α cellulose, which is true cellulose. Acidification of the extract precipitates β cellulose. The portion that dissolves in base but does not precipitate with acid is γ cellulose.
  • 15.
    Cellulose can beassayed using a method described by Updegraff in 1969, where the fiber is dissolved in acetic and nitric acid to remove lignin, hemicellulose, and xylosans. The resulting cellulose is allowed to react with anthrone in sulfuric acid. The resulting coloured compound is assayed spectrophotometrically at a wavelength of approximately 635 nm. In addition, cellulose is represented by the difference between acid detergent fiber (ADF) and acid detergent lignin (ADL). [edit] Biosynthesis Location and arrangement of cellulose microfibrils in the plant cell wall In vascular plants cellulose is synthesized at the plasma membrane by rosette terminal complexes (RTCs). The RTCs are hexameric protein structures, approximately 25 nm in diameter, that contain the cellulose synthase enzymes that synthesise the individual cellulose chains.[20] Each RTC floats in the cell's plasma membrane and "spins" a microfibril into the cell wall. RTCs contain at least three different cellulose synthases, encoded by CesA genes, in an unknown stoichiometry.[21] Separate sets of CesA genes are involved in primary and secondary cell wall biosynthesis. Cellulose synthesis requires chain initiation and elongation, and the two processes are separate. CesA glucosyltransferase initiates cellulose polymerization using a steroid primer, sitosterol- beta-glucoside, and UDP-glucose.[22] Cellulose synthase utilizes UDP-D-glucose precursors to elongate the growing cellulose chain. A cellulase may function to cleave the primer from the mature chain. Cellulose is also synthesised by animals, particularly in the tests of ascidians (where the cellulose was historically termed "tunicine") although it is also a minor component of mammalian connective tissue.[23] [edit] Breakdown (cellulolysis) Cellulolysis is the process of breaking down cellulose into smaller polysaccharides called cellodextrins or completely into glucose units; this is a hydrolysis reaction. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides.[24] Processes do exist however for the breakdown of
  • 16.
    cellulose such asthe Lyocell process [25] which uses a combination of heated water and acetone to break down the cellulose strands. Most mammals have only very limited ability to digest dietary fibres such as cellulose. Some ruminants like cows and sheep contain certain symbiotic anaerobic bacteria (like Cellulomonas) in the flora of the rumen, and these bacteria produce enzymes called cellulases that help the microorganism to break down cellulose; the breakdown products are then used by the bacteria for proliferation. The bacterial mass is later digested by the ruminant in its digestive system (stomach and small intestine). Similarly, lower termites contain in their hindguts certain flagellate protozoa which produce such enzymes; higher termites contain bacteria for the job. Some termites may also produce cellulase of their own.[26] Fungi, which in nature are responsible for recycling of nutrients, are also able to break down cellulose. The enzymes utilized to cleave the glycosidic linkage in cellulose are glycoside hydrolases including endo-acting cellulases and exo-acting glucosidases. Such enzymes are usually secreted as part of multienzyme complexes that may include dockerins and carbohydrate-binding modules.[27] [edit] Hemicellulose Main article: Hemicellulose Hemicellulose is a polysaccharide related to cellulose that comprises about 20% of the biomass of most plants. In contrast to cellulose, hemicellulose is derived from several sugars in addition to glucose, especially xylose but also including mannose, galactose, rhamnose, and arabinose. Hemicellulose consists of shorter chains – around 200 sugar units. Furthermore, hemicellulose is branched, whereas cellulose is unbranched. [edit] Derivatives The hydroxyl groups (-OH) of cellulose can be partially or fully reacted with various reagents to afford derivatives with useful properties like mainly cellulose esters and cellulose ethers (-OR). In principle, though not always in current industrial practice, cellulosic polymers are renewable resources. Ester derivatives include: Cellulose Reagent Example Reagent Group R ester Organic Organic Acetic acid and acetic Cellulose acetate H or -(C=O)CH3 esters acids anhydride Acetic acid and acetic Cellulose triacetate -(C=O)CH3 anhydride
  • 17.
    Cellulose propionate Propanoic acid H or -(C=O)CH2CH3 Cellulose acetate Acetic acid and propanoic H or -(C=O)CH3 or - propionate acid (C=O)CH2CH3 Cellulose acetate H or -(C=O)CH3 or - Acetic acid and butyric acid butyrate (C=O)CH2CH2CH3 Inorganic Inorganic Nitrocellulose Nitric acid or another H or -NO2 esters acids (cellulose nitrate) powerful nitrating agent Sulfuric acid or another Cellulose sulfate H or -SO3H powerful sulfuring agent The cellulose acetate and cellulose triacetate are film- and fiber-forming materials that find a variety of uses. The nitrocellulose was initially used as an explosive and was an early film forming material. With camphor, nitrocellulose gives celluloid. Ether derivatives include: Water E Cellulose Group R = H Reagent Example Reagent solubilit Application numbe ethers or y r Cold Halogenoalkan Methylcellulo Chloromethan Alkyl -CH3 water E461 es se e soluble A commercial thermoplasti c used in Water coatings, Ethylcellulose Chloroethane -CH2CH3 insolubl E462 inks, binders, e and controlled- release drug tablets Ethyl methyl Chloromethan -CH3 or - E465 cellulose e and CH2CH3
  • 18.
    chloroethane Cold/ho Gelling and Hydroxyalk Hydroxyethyl Ethylene Epoxides -CH2CH2OH t water thickening yl cellulose oxide soluble agent Hydroxypropy - Cold Propylene l cellulose CH2CH(OH)C water E463 oxide (HPC) H3 soluble Chloromethan Hydroxyethyl Cold Production of e and -CH3 or - methyl water cellulose ethylene CH2CH2OH cellulose soluble films oxide Viscosity Hydroxypropy Chloromethan modifier, -CH3 or - Cold l methyl e and gelling, CH2CH(OH)C water E464 cellulose propylene foaming and H3 soluble (HPMC) oxide binding agent Ethyl Chloroethane -CH2CH3 or— hydroxyethyl and ethylene E467 CH2CH2OH cellulose oxide Often used as its sodium Carboxymethy Cold/Ho Carboxyalk Halogenated Chloroacetic salt, sodium l cellulose -CH2COOH t water E466 yl carboxylic acids acid carboxymeth (CMC) soluble yl cellulose (NaCMC) The sodium carboxymethyl cellulose can be cross-linked to give the croscarmellose sodium (E468) for use as a disintegrant in pharmaceutical formulations. [edit] References 1. ^ Nishiyama, Yoshiharu; Langan, Paul; Chanzy, Henri (2002). "Crystal Structure and Hydrogen-Bonding System in Cellulose Iβ from Synchrotron X-ray and Neutron Fiber Diffraction". J. Am. Chem. Soc 124 (31): 9074–82. doi:10.1021/ja0257319. PMID 12149011.. ab 2. ^ Crawford, R. L. (1981). Lignin biodegradation and transformation. New York: John Wiley and Sons. ISBN 0-471-05743-6.
  • 19.
    3. ^ Updegraff DM (1969). "Semimicro determination of cellulose in biological materials". Analytical Biochemistry 32 (3): 420–424. doi:10.1016/S0003-2697(69)80009-6. PMID 5361396. 4. ^ Cellulose. (2008). In Encyclopædia Britannica. Retrieved January 11, 2008, from Encyclopædia Britannica Online. 5. ^ Chemical Composition of Wood 6. ^ G. Buschle-Diller, C. Fanter, F. Loth (April 1999). "Structural changes in hemp fibers as a result of enzymatic hydrolysis with mixed enzyme systems". Textile Research Journal 69 (4): 244-251. http://www.globalhemp.com/1999/04/structural-changes-in-hemp-fibers-as-a-result-of-enzymatic- hydrolysis-with-mixed-enzyme-systems.html. 7. ^ Slavin, JL; Brauer, PM; Marlett, JA (1981). "Neutral detergent fiber, hemicellulose and cellulose digestibility in human subjects.". The Journal of Nutrition 111 (2): 287–97. PMID 6257867. 8. ^ Joshi, S; Agte, V (1995). "Digestibility of dietary fiber components in vegetarian men.". Plant foods for human nutrition (Dordrecht, Netherlands) 48 (1): 39–44. doi:10.1007/BF01089198. PMID 8719737. 9. ^ A. Payen (1838) "Mémoire sur la composition du tissu propre des plantes et du ligneux" (Memoir on the composition of the tissue of plants and of woody [material]), Comptes rendus, vol. 7, pages 1052-1056. Payen added appendices to this paper on December 24, 1838 (see: Comptes rendus, vol. 8, page 169 (1839)) and on February 4, 1839 (see: Comptes rendus, vol. 9, page 149 (1839)). A committee of the French Academy of Sciences reviewed Payen's findings in : Jean-Baptiste Dumas (1839) "Rapport sur un mémoire de M. Payen, relatif à la composition de la matière ligneuse" (Report on a memoir of Mr. Payen, regarding the composition of woody matter), Comptes rendus, vol. 8, pages 51-53. In this report, the word "cellulose" is coined and author points out the similarity between the empirical formula of cellulose and that of "dextrine" (starch). The above articles are reprinted in: Brongniart and Guillemin, eds., Annales des sciences naturelles ..., 2nd series, vol. 11 (Paris, France: Crochard et Cie., 1839), pages 21-31. 10. ^ Young, Raymond (1986). Cellulose structure modification and hydrolysis. New York: Wiley. ISBN 0-471- 82761-4. ab 11. ^ Klemm, Dieter; Brigitte Heublein, Hans-Peter Fink, Andreas Bohn (2005). "Cellulose: Fascinating Biopolymer and Sustainable Raw Material". ChemInform 36 (36). doi:10.1002/chin.200536238. 12. ^ Weiner, Myra L.; Lois A. Kotkoskie (2000). Excipient Toxicity and Safety. New York ; Dekker. p. 210. ISBN 0-8247-8210-0. 13. ^ Peng, B. L., Dhar, N., Liu, H. L. and Tam, K. C. (2011). "Chemistry and applications of nanocrystalline cellulose and its derivatives: A nanotechnology perspective.". The Canadian Journal of Chemical Engineering 89 (5): 1191–1206. http://www.arboranano.ca/pdfs/Chemistry%20and%20applications%20of%20nanocrystalline%20cellulos e%20and%20its%20derivatives%20A%20nanotechnology%20perspective-2011.pdf. 14. ^ Lawrence Pranger and Rina Tannenbaum "Biobased nanocomposites prepared by in situ polymerization of furfuryl alcohol with cellulose whiskers or montmorillonite clay" Macromolecules 41 (2008) 8682. http://dx.doi.org/10.1021/ma8020213 15. ^ Holt-Gimenez, Eric 2007. Biofuels: Myths of the Agrofuels Transition. Backgrounder. Institute for Food and Development Policy, Oakland, CA. 13:2 16. ^ Charles A. Bishop, ed. (2007). Vacuum deposition onto webs, films, and foils, Volume 0, Issue 8155. p. 165. ISBN 0-8155-1535-9. http://books.google.com/books?id=vP9E3z7o6iIC&pg=PA165. 17. ^ Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki (2006). "Cooking cellulose in hot and compressed water". Chemical Communications (31): 3293. doi:10.1039/b605812d. 18. ^ Structure and morphology of cellulose by Serge Pérez and William Mackie, CERMAV-CNRS, 2001. Chapter IV. 19. ^ Stenius, Per (2000). "1". Forest Products Chemistry. Papermaking Science and Technology. 3. Finland: Fapet OY. p. 35. ISBN 952-5216-03-9. 20. ^ Kimura, S; Laosinchai, W; Itoh, T; Cui, X; Linder, CR; Brown Jr, RM (1999). "Immunogold labeling of rosette terminal cellulose-synthesizing complexes in the vascular plant vigna angularis". The Plant cell 11 (11): 2075–86. doi:10.2307/3871010. JSTOR 3871010. PMC 144118. PMID 10559435. //www.ncbi.nlm.nih.gov/pmc/articles/PMC144118/. 21. ^ Taylor, N. G. (2003). "Interactions among three distinct CesA proteins essential for cellulose synthesis". Proceedings of the National Academy of Sciences 100 (3): 1450. doi:10.1073/pnas.0337628100.
  • 20.
    22. ^ Peng,L; Kawagoe, Y; Hogan, P; Delmer, D (2002). "Sitosterol-beta-glucoside as primer for cellulose synthesis in plants". Science 295 (5552): 147–50. doi:10.1126/science.1064281. PMID 11778054. 23. ^ Endean, The Test of the Ascidian, Phallusia mammillata, Quarterly Journal of Microscopical Science, Vol. 102, part 1, pp. 107-117, 1961. 24. ^ David G. Barkalow, Roy L. Whistler, "Cellulose", in AccessScience, McGraw-Hill, doi:10.1036/1097- 8542.118200. Retrieved 11 January 2008. 25. ^ H.Lyocell, "Cellulose" Issue 41, pp 419 26. ^ Tokuda, G; Watanabe, H (22 June 2007). "Hidden cellulases in termites: revision of an old hypothesis". Biology Letters 3 (3): 336–339. doi:10.1098/rsbl.2007.0073. PMC 2464699. PMID 17374589. http://rsbl.royalsocietypublishing.org/content/3/3/336.long 27. ^ Brás, Natércia; N. M. F. S. A. Cerqueira, P. A. Fernandes, M. J. Ramos (2008). "Carbohydrate Binding Modules from family 11: Understanding the binding mode of polysaccharides". International Journal of Quantum Chemistry 108 (11): 2030–2040. doi:10.1002/qua.21755. [edit] External links Structure and morphology of cellulose by Serge Pérez and William Mackie, CERMAV-CNRS Cellulose, by Martin Chaplin, London South Bank University Clear description of a cellulose assay method at the Cotton Fiber Biosciences unit of the USDA. Cellulose films could provide flapping wings and cheap artificial muscles for robots - TechnologyReview.com Using cellulase enzymes in the bioethanol process A list of cellulolytic bacteria v t e Types of carbohydrates Aldose Furanose General Ketose Pyranose Anomer Geometry Cyclohexane conformation Mutarotation
  • 21.
    Aldodiose Dioses o Glycolaldehyde Aldotriose o Glyceraldehyde Trioses Ketotriose o Dihydroxyacetone Aldotetroses o Erythrose Tetroses o Threose Ketotetrose o Erythrulose Monosaccharides Aldopentose o Arabinose o Lyxose o Ribose o Xylose Pentoses Deoxy sugar o Deoxyribose Ketopentose o Ribulose o Xylulose Aldohexose Hexoses o Allose o Altrose
  • 22.
    o Galactose o Glucose o Gulose o Idose o Mannose o Talose Deoxy sugar o Fucose o Fuculose o Rhamnose Ketohexose o Fructose o Psicose o Sorbose o Tagatose Ketoheptose Heptoses o Mannoheptulose o Sedoheptulose Octose >7 Nonose o Neuraminic acid Cellobiose Multiple Disaccharides Lactose Maltose Sucrose
  • 23.
    Trehalose Turanose Maltotriose Trisaccharides Melezitose Raffinose Tetrasaccharides Stachyose Acarbose Fructooligosaccharide (FOS) Other Galactooligosaccharide (GOS) oligosaccharides Isomaltooligosaccharide (IMO) Maltodextrin Mannan-oligosaccharides (MOS) Beta-glucan o Lentinan o Sizofiran o Zymosan Cellulose Polysaccharides Chitin Dextrin / Dextran Fructose / Fructan o Inulin Galactose / Galactan Glucose / Glucan o Glycogen
  • 24.
    Levan beta 2→6 Mannan Starch o Amylopectin o Amylose biochemical families: carbohydrates o alcohols o glycoproteins o glycosides lipids o eicosanoids o fatty acids / intermediates o phospholipids o sphingolipids o steroids nucleic acids o constituents / intermediates proteins o amino acids / intermediates tetrapyrroles / intermediates v t e Paper History Wood pulp Materials Fiber crop Papyrus
  • 25.
    Paper chemicals Blotting Bond Construction Copy Cotton Crêpe Glassine India Kraft Laid Manila Newsprint Types Onionskin Origami Rag Rice Security Seed Tar Tissue Tracing Transfer Wallpaper Waterproof Wax Wood-free
  • 26.
    Wove Size Specifications Density Papermaking Paper engineering Paper mill Paper machine Production Sulfite process Kraft process Soda pulping Paper recycling List of paper mills In Europe Industry In the United States In Japan Bleaching of wood pulp Issues Environmental impact of paper Paper pollution Category Commons Retrieved from "http://en.wikipedia.org/w/index.php?title=Cellulose&oldid=531575776" Categories: Cellulose Excipients Papermaking Polysaccharides
  • 27.
    Hidden categories: Chemical compounds which do not have a ChemSpiderID Chemboxes which contain changes to verified fields Navigation menu Personal tools Create account Log in Namespaces Article Talk Variants Views Read Edit View history Actions Search Navigation Main page Contents Featured content Current events Random article Donate to Wikipedia Interaction Help About Wikipedia Community portal Recent changes
  • 28.
    Contact Wikipedia Toolbox What links here Related changes Upload file Special pages Permanent link Page information Cite this page Print/export Create a book Download as PDF Printable version Languages ‫ال عرب ية‬ Azərbaycanca Беларуская Б Български Bosanski Català Česky Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara ‫ف ار سی‬ Français Galego 한국어 Hrvatski Ido Bahasa Indonesia Íslenska Italiano ‫עברית‬ ქართული Қазақша
  • 29.
    Kreyòl ayisyen Latviešu Lietuvių Magyar Македонски მარგალური Bahasa Melayu Nederlands 日本語 Occitan Polski Português Română RunaSimi Русский Shqip Simple English Slovenčina Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Basa Sunda Suomi Svenska Türkçe Українська Tiếng Việt 中文 This page was last modified on 6 January 2013 at 05:57. Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. Contact us Privacy policy About Wikipedia Disclaimers Mobile view
  • 30.
    Introduction Some useful constantsin thermodynamics: 1 eV = 9.6522E4 J/mol k Boltzmann's constant = 1.38E-23 J/K volume: 1 cm3 = 0.1 kJ/kbar = 0.1 J/bar mole: 1 mole of a substance contains Avogadro's number (N = 6.02E23) of molecules. Abbreviated as 'mol'. atomic weights are based around the definition that 12C is exactly 12 g/mol R gas constant = Nk = 8.314 J mol-1 K-1 Units of Temperature: Degrees Celsius and Kelvin The Celsius scale is based on defining 0 °C as the freezing point of water and 100°C as the boiling point. The Kelvin scale is based on defining 0 K, "absolute zero," as the temperature at zero pressure where the volumes of all gases is zero--this turns out to be -273.15 °C. This definition means that the freezing temperature of water is 273.15 K. All thermodynamic calculations are done in Kelvin! kilo and kelvin: write k for 1000's and K for kelvin. Never write °K. Units of Energy: Joules and Calories Joules and calories and kilocalories: A calorie is defined as the amount of energy required to raise the temperature of 1 g of water from 14.5 to 15.5°C at 1 atm. 4.184 J = 1 cal; all food 'calories' are really kcal.
  • 31.
    Many times itis easiest to solve equations or problems by conducting "dimensional analysis," which just means using the same units throughout an equation, seeing that both sides of an equation contain balanced units, and that the answer is cast in terms of units that you want. As an example, consider the difference between temperature (units of K) and heat (units of J). Two bodies may have the same temperature, but contain different amounts of heat; likewise, two bodies may contain the same heat, but be at different temperatures. The quantity that links these two variables must have units of J/K or K/J. In fact, the heat capacity C describes the amount of heat dQ involved in changing one mole of a substance by a given temperature increment dT: dQ = CdT The heat capacity C is then C = dQ/dT and must have units of J K-1 mol-1. (The specific heat is essentially the same number, but is expressed per gram rather than per mole.) Don't forget significant digits. 1*2=2; 1.1*2=2; 1.1*2.0=2.2; 1.0*2.0=2.0 Why Thermodynamics? Think about some everyday experiences you have with chemical reactions. Your ability to melt and refreeze ice shows you that H2O has two phases and that the reaction transforming one to the other is reversible--apparently the crystallization of ice requires removing some heat. Frying an egg is an example of an irreversible reaction. If you dissolve halite in water you can tell that the NaCl is still present in some form by tasting the water. Why does the NaCl dissolve? Does it give off heat? Does it require energy? How is it that diamond, a high-pressure form of C, can coexist with the low pressure form, graphite, at Earth's surface? Do diamond and graphite both have the same energy? If you burn graphite and diamond, which gives you more energy? When dynamite explodes, why does it change into a rapidly expanding gas, which provides the energy release, plus a few solids? Chemical thermodynamics provides us with a means of answering these questions and more. A Few Definitions A system is any part of the universe we choose to consider. Matter and energy can flow in or out of an open system but only energy can be added to or subtracted from a closed system. An isolated system is one in which matter and energy are conserved. A phase is a homogeneous body of matter. The components of a system are defined by a set of chemical formula used to describe the system. The phase rule:
  • 32.
    F + P= C + 2. Extensive parameters are proportional to mass (e.g., V, mass, energy). Intensive parameters are independent of mass (e.g., P, T); these are the "degrees of freedom" F contained in the phase rule. Thermodynamics: Power and Limitations Thermodynamics allows you to predict how chemical systems should behave from a supra-atomic "black-box" level--it says nothing about how chemical systems will behave. Thermodynamics also pertains to the state of a system, and says nothing about the path taken by the system in changing from one state to another. Chemical Reactions and Equations How to write chemical reactions; stoichiometry. Mass and charge balance: e.g., 2Fe3+ + 3H2O = Fe2O3 + 6H+ Reaction-Produced Change in Mass, Density, Volume The change in volume rV of a reaction is the volume V of the products minus the volume of the reactants: rV = Vproducts - Vreactants Thus, if the products are smaller than the reactants, rV < 0. In a generalized reaction such as aA + bB ... = cC + dD... rV = cVC + dVD - aVA - bVB This sort of additive relationship is true for other state variables and is usually stated as r i i where i are the stoichiometric coefficients, positive for products and negative for reactants. What Actually Drives Reactions? Is it Energy? Can We Just Calculate or Measure the Energy Difference of Reactants and Products and Know Which Way the Reaction Will Go?
  • 33.
    For many yearspeople felt that chemical reactions occurred because the reactants had some kind of energy to give up (i.e., use to do work)--and that therefore the energy of the products would be less than the energy of the reactants. However, we all know that when ice melts it consumes rather than releases heat, so there must be more to the story behind why chemical reactions occur. Le Chatelier's Principle "If a change is made to a system, the system will respond so as to absorb the force causing the change." Equilibrium A mechanical analogy for chemical change is that of a ball rolling down a slope with multiple valleys; we explain the ball's behavior by saying that mechanical systems have a tendency to reduce their potential energy. At equilibrium none of the properties of a system change with time. A system at equilibrium returns to equilibrium if disturbed. "Stable" describes a system or phase in its lowest energy state. "Metastable" describes a system or phase in any other energy state. The figure above shows the mechanical analogy for H2O at -5°C and + 5°C and 1 atm. Left: at -5°C, solid H2O has the lowest possible energy state. Right: at +5°C, liquid H2O has the lowest possible energy state. When solid H2O is actually present at +5°C, the difference between the free energy of solid H2O and liquid H2O is available to drive the reaction to form the stable solid H2O phase, and the reaction will go to completion if kinetically possible.
  • 34.
    Energy: How DoWe Calculate and Measure Energy and How Can We Use this Knowledge to Predict Reaction Behavior? Thermodynamics works equally well to describe any kind of work or energy: magnetic, potential, kinetic, etc. For geological systems we typically talk about pressure-volume work, which, because mechanical work is F x, you can imagine might be P V or V P Because we noted that rV < 0 if the products are smaller than the reactants, we choose to write the P- V work term as -P V so that a decrease in volume - V is seen as positive work or that an increase in volume + V results in a decrease in crystal energy. The absolute energy of a body can be calculated from Einstein's equation U=mc2, but the presence of the c2 term means that the energy of any system is quite large and that measuring this energy is impractical. It is more practical to measure differences in energy U, and we always discuss or measure differences relative to some arbitrary standard state. Analogous to this might be if someone in Namibia asked you to measure the elevation of the crests of waves at Campus Point--without agreement on some kind of standard, you wouldn't be able to do much more than measure the heights of individual waves. If however, you could both agree on an equivalent "sea level" at both localities, you could then compare the absolute elevations of the wave crests. A typical thermodynamic standard state is normal laboratory conditions: 25°C (298.15 K) and 1 atm (often called STP for standard temperature and pressure). The internal energy U of a mineral is the sum of the potential energy stored in the interatomic bonds and the kinetic energy of the atomic vibrations. Thus, you might expect that weakly bonded minerals have relatively low potential energy and thus low internal energy, and when a mineral is cold such that its atomic vibrations are slow it will have low kinetic energy and thus low internal energy. Internal energies are always defined relative to some non-zero standard state, so we typically talk about changes in internal energy dU. An Aside on Differences and Differentials What's the difference among , d , and ? is used to indicate any kind of difference.
  • 35.
    d is usedto indicate a differential. is used to indicate a partial differential. For example, the partial differential, with respect to y, of f(x,y) = x3y4 is = 4x3y3 First Law of Thermodynamics Adding heat Q to a crystal increases its internal energy U: dU dQ ( indicates 'proportional') but if the crystal is allowed to expand, some of the added energy will be consumed by expansion dV, so the total energy of the crystal is reduced: dU = dQ - PdV This is effectively the First Law of Thermo: that total energy (heat + P-V work) is conserved. Heat Capacity Heat capacity C describes the amount of heat required to change the temperature of a substance: C= By definition, the heat capacity of water at 15°C is 1 cal K-1 g-1 or 18 cal K-1 mol-1 (i.e., the heat required to heat 1 gram of water from 14.5 to 15.5°C is 1 calorie). Heat capacities of solids approach zero as absolute zero is approached: C=0 The heat capacity is written with a subscript P or V depending on whether it obtains for constant pressure CP or constant volume CV. As an aside, 2 CP = CV + TV /
  • 36.
    where and arethe expansivity and compressibility--for solids the difference between CP and CV is minimal and can be ignored as a first approximation. For gases, CP = CV + R, and is quite significant. Heat capacities are measured by calorimetry and often fit by a function of the form: CP = a + bT + cT-2 + dT-0.5 but there are other expansions for the heat capacity involving more or fewer terms. Below are some examples of heat capacities of minerals. Note how silicates have a nearly constant heat capacity of ~1 J K-1 g-1 above 400K.
  • 37.
    Enthalpy We have alreadytalked about the familiar concept of heat as energy. Let's define another measure of energy called enthalpy H--a kind of measure of the thermal energy of a crystal. As we will see below,
  • 38.
    dH = dQ+ VdP Recall that we interpreted dU = dQ - PdV to mean that the internal energy change is the heat change minus the energy lost to relaxation of the crystal. Thus, dH = dQ + VdP means that the enthalpy change is the heat change plus the energy the crystal gains by virtue of not being allowed to expand. Enthalpy includes the vibrational and bonding energy at absolute zero H0°, plus the energy required to increase temperature: H = H0° + CPdT i.e., we can find the enthalpy change H produced by changing temperature by integrating the heat capacity CP: H= CPdT Integration Reminder How to integrate the heat capacity (to determine change in enthalpy H): CP dT = (a + bT + cT-2 + dT-0.5) =aT + bT2/2 - c/T + 2dT0.5 and is evaluated as =a(T2 - T1) + b(T22 - T12)/2 - c/(T2-1 - T1-1) + 2d(T20.5 - T10.5) How to integrate the heat capacity divided by T (to determine entropy S): dT = (a/T + b + cT-3 + dT-1.5)
  • 39.
    = a lnT + b T - c T-2/2 - 2 d T -0.5 and is evaluated as a(ln T2 - ln T1) + b(T2 - T1) - c(T2-2 - T1-2)/2 - 2d(T2-0.5 - T1-0.5) As an example, let's calculate the change in enthalpy H°298-1000 that results from heating quartz from 298 K to 1000 K, given the following heat capacity expansion coefficients: a = 104.35, b = 6.07E-3, c = 3.4E+4, d = -1070 (CP dT = (a + bT + cT-2 + dT-0.5) =aT + bT2/2 - c/T + 2dT0.5 evaluated from 298 to 1000K =a*(1000-298) + b*(10002-2982)/2 - c*(1000-1-298-1) + 2d*(10000.5-2980.5) = 45.37 kJ/mol Relation Among Enthalpy, Heat, and Heat Capacity ( HP= QP) An important relationship between enthalpy change H and heat change Q is revealed by differentiating H = U + PV to obtain the total differential dH = dU + PdV + VdP substituting dU = dQ - PdV we get dH = dQ + VdP dividing by dT gives = -V at constant pressure, = 0, leaving =
  • 40.
    which is equalto CP: = = CP Determining Enthalpies Thus, if we want to measure how the internal energy U of a crystal changes U with increasing temperature at constant pressure, we want to know H, and we can get that by integrating the heat capacity CP over the temperature range of interest. There's another way to measure H, though: calorimetry. By dissolving a mineral in acid and measuring the heat produced by the dissolution, we get a heat of dissolution (usually positive). The enthalpy of "formation" fH° of the mineral is then just the opposite of the heat of dissolution (usually negative). Exceptions to the "usually positive/negative" rule include CN, HCN, Cu2+, Hg2+, NO, Ag+, and S2-. Enthalpies of formation appear in tables of thermodynamic data and are usually referenced to 298 K and 1 atm. Enthalpy of Reaction To get an enthalpy of reaction rH° we can measure the enthalpies of formation of the reactants and products fH° and then take the difference between them as rH° = fH°products- fH°reactants For example, we can compute the enthalpy of the reaction anhydrite + water = gypsum: CaSO4 + 2H2O = CaSO4 2H2O from Ca + S + 2O2 = CaSO4 fH° = -1434.11 kJ/mol H2 + 0.5O2 = H2O fH° = -285.830 kJ/mol Ca + S + 3O2 + 2H2 = CaSO4 2H2O fH° = -2022.63 kJ/mol Thus, rH° = fH°gypsum - fH°anhydrite - fH°water = -16.86 kJ/mol. Exothermic vs. Endothermic
  • 41.
    If rH° <0 the reaction produces a reduction in enthalpy and is exothermic (heat is given up by the rock and gained by the surroundings). If rH° > 0 the reaction produces an increase in enthalpy and is endothermic (heat from the surroundings is consumed by the rock). An easy way to remember this is that spontaneous reactions produce a decrease in internal energy, and because we know that UP HP a decrease in HP is also a decrease in UP. Calculating fH° at Temperatures Other Than 298 K So far we know how to calculate the change in enthalpy caused by heating and we know that we can get enthalpies of formation from tables. What if we want to know the enthalpy of formation of a mineral at a temperature other than 298 K? We do this by calculating rCP for the reaction that forms the mineral of interest: rCP = rCPproducts - rCPreactants and then integrating. Thus, for example if we want to know fH° for quartz at 1000 K, we get coefficients for the heat capacities of Si, O2 and SiO2: compound a b c d Si 31.778 5.3878E-4 -1.4654E5 -1.7864E2 O2 48.318 -6.9132E-4 4.9923E5 -4.2066E2 SiO2 104.35 6.07E-3 3.4E-4 -1070 for the reaction Si + O2 = SiO2 and we calculate a = 24.254 b = 6.2225E-3 c = -3.5E5 d = -470.7 and thus, fH°1000 - fH°298 = CP dT = a*(1000-298) + b/2*(10002-2982) - c*(1000-1-298-1) 0.5 0.5 +2 d*(1000 -298 ) = 5.511 kJ/mol
  • 42.
    This is thechange in the enthalpy of formation that results from heating. We add this to the enthalpy of formation at 298 K to get the enthalpy of formation at 1000 K: fH°1000 =( fH°1000 - fH°298) + fH°298 = 5.511 - 910.700 = -905.2 kJ/mol In other words, forming quartz from the elements at 1000 K yields slightly less heat than at 298 K. Compare this with the change in enthalpy H°298-1000 that results from heating quartz from 298 K to 1000 K, which we calculated is 45.37 kJ/mol. Entropy We have discussed the intuitive statement that reactions probably proceed because the reactants can decrease their internal energy by reacting. We also noted that internal energy scales with enthalpy, suggesting that reactions might 'go' because of a decrease in enthalpy. However, we then noted that not all reactions give off heat--some, such as the melting of ice, proceed in spite of consuming heat. Moreover, there are other processes that proceed in the apparent absence of any heat change: e.g., mixing of gases or the spreading of dye in water. What is it that causes these reactions to proceed spontaneously even if the heat change is zero or endothermic? The answer is entropy S, which is a measure of the order or disorder. Entropy has three sources: configurational, electronic, and vibrational. Configurational entropy refers to the entropy resulting from imperfect mixing of different atoms in the same site in a crystal, and is described by the Boltzmann distribution: Sconfigurational = k ln (This is engraved on Boltzmann's tomb in Vienna!) where is the probability that a given number of atoms in a given number of sites will have a particular configuration. For N atomic sites that can contain fraction XA A atoms and XB B atoms, =
  • 43.
    N is alwayslarge where moles of material are concerned, so we can simplify this (using Stirling's approximation) to S = - n R (XA ln XA + XB ln XB) where n is the number of sites per mole. For example in cordierite there are 4 Al atoms and 5 Si atoms distributed over 9 tetrahedral sites. For a random distribution the entropy is S = - 9 R (4/9 ln 4/9 + 5/9 ln 5/9) = 51.39 J mol-1 K-1 Note that the form of the configurational entropy equation (and electronic entropy as well) indicates that if XA or XB are 0 or 1, Sconfig is zero: Electronic entropy arises when an electron in an unfilled orbital can occupy more than one orbital; e.g., for Ti3+, the single 3d electron can occupy one of three possible t2g orbitals and Selectronic = 9 J mol-1 K-1. Vibrational (or calorimetric) entropy arises because the energy of lattice vibrations can only increase or decrease in discrete steps and the energy quanta (phonons) can be distributed within the possible energy steps in different ways. Vibrational entropy is very difficult to calculate from statistical mechanics but can be calculated easily from heat capacity. Here's why: The entropy of a system always increases during irreversible processes; i.e., for a reversible process, dS = 0, whereas for irreversible processes dS >0. This is the Second Law of Thermo--better known as "You can't feed s**t into the rear of a horse and get hay out the front." If a mineral becomes more ordered during a reaction, reducing its entropy, the heat liberated must increase the entropy of the surroundings by an even greater amount. Thus, we write dS > then
  • 44.
    > and recalling that CP = then > and S= dT In other words, the vibrational entropy can be found by integrating the heat capacity divided by temperature. In a perfectly ordered, pure crystalline material the entropy is zero. This is a simple statement of the Third Law of Thermo, which follows from the fact that heat capacities approach zero at zero K: C=0 However, because the rate of atomic diffusion also goes to zero at 0 K, all compounds have some zero- point entropy S°0. Entropy is thus the only thermodynamic potential for which we can calculate an absolute value. What we typically do is determine the heat capacity from near absolute zero to ambient conditions and then integrate it to get the (absolute) entropy (in fact this gives us only the vibrational entropy and ignores configurational and electronic contributions to entropy).
  • 45.
    Entropy Change ofReaction Just like rH and rV, we can calculate entropies of reactions by using absolute entropies S and calculating a difference in entropy rS. For example, if we know that S°CaSO4 = 106.7 J mol-1 K-1 S°Ca = 41.42 J mol-1 K-1 S°S = 31.80 J mol-1 K-1 S°O2 = 205.138 J mol-1 K-1 then the entropy of the reaction Ca + S + 2O2 = CaSO4 is rS° = 106.7 - 41.42 - 31.80 - 2 * 205.138 = -376.8 J mol-1 K-1
  • 46.
    Energy Associated WithEntropy The units of entropy suggest that the energy associated with S scales with temperature: dU -TS (The minus sign is there for reasons similar to the -PV we encountered earlier.) The energy associated with configurational entropy in the Al4Si5 cordierite we talked about earlier looks like this: The energy associated with vibrational entropy in tremolite, quartz, and chalcopyrite looks like this: (Josiah Willard) Gibbs Free Energy of a Phase The Gibbs free energy G is the thermodynamic potential that tells us which way a reaction goes at a given set of physical conditions--neither the enthalpy change nor the entropy change for a reaction
  • 47.
    alone can provideus with this information. The two measures of energy (enthalpy H and entropic energy TS) are brought together in the Gibbs free energy equation: (the chemical potential is the equivalent for a component) G = U + PV - TS which says that the Gibbs free energy G is the internal energy of the crystal U plus the energy the crystal gains by virtue of not being allowed to expand minus the entropic energy TS. Recalling that H = U + PV we can write this in a more understandable way G = H - TS which says that G is the difference between the heat energy and the entropic energy. Relationship Among G, S, and V If we differentiate G = U + PV - TS to obtain dG = dU + PdV + VdP - TdS - SdT and substitute
  • 48.
    TdS = dU+ PdV (this comes from dS = dQ/T and dU = dQ - PdV); we are left with dG = VdP - SdT meaning that changes in Gibbs free energy are produced by changes in pressure and temperature acting on the volume and entropy of a phase. Realize that when we write dG = VdP - SdT we are implicitly writing dG = dP - dT which means that =V and = -S
  • 49.
    These relations indicatethat the change in Gibbs free energy with respect to pressure is the molar volume V and the change in Gibbs free energy with respect to temperature is minus the entropy S. Gibbs Free Energy of Formation The defining equation for Gibbs free energy G = H - TS can be written as G= H-T S such that the Gibbs free energy of formation fG° is fG° = fH° -T fS° For example, to calculate the Gibbs free energy of formation of anhydrite, we can use fH°CaSO4 = -1434.11 kJ/mole S°CaSO4 = 106.7 J mol-1 K-1 S°Ca = 41.42 J mol-1 K-1
  • 50.
    S°S = 31.80J mol-1 K-1 S°O2 = 205.138 J mol-1 K-1 and we calculate the entropy of formation of anhydrite fS° = S°CaSO4 - S°Ca - S°S - 2 * S°O2 = -376.796 J mol-1 K-1 and then use fG° = fH° -T fS° = -1434,110 - 298.15 * -376.796 = -1321.77 kJ/mol Gibbs Free Energy of Reaction We can write the Gibbs free energy of reaction as the enthalpy change of reaction minus the entropic energy change of reaction rG = rH -T rS If the heat energy equals the entropic energy rH =T rS then rG =0 and there is no reaction. Finally we have come to a satisfying point--we can now determine whether a given reaction will occur if we know H and S, and both of these are measurable or can be calculated.
  • 51.
    If rG <0, the Gibbs free energy of the products is lower than the Gibbs free energy of the reactants and the reaction moves to produce more products. If rG > 0, the Gibbs free energy of the products is greater than the Gibbs free energy of the reactants and the reaction moves to produce more reactants. For example, to calculate rG° at STP for the reaction aragonite = calcite we use rH° = 370 J rS° = 3.7 J mol-1 K-1 to calculate rG° = 370 - 298.15 * 3.7 = -733 J/mol The negative value of G tells us that calcite has lower Gibbs free energy and that the reaction runs forward (aragonite calcite). Clapeyron Relation There is a useful relation between the slope of a reaction in PT space (i.e., dP/dT) and the entropy and volume changes of the reaction that follows from rG = VrdP - SrdT At equilibrium G = 0, such that
  • 52.
    rVdP = rSdT or = So, the P-T slope of a reaction is equal to the ratio of the entropy change to the volume change. Alternatively, along the equilibrium curve, the changes in pressure times the volume change are equal to changes in temperature times the entropy change. This is the Clapeyron Equation. So, a phase diagram is a kind of free energy map. = along an equilibrium, < at high P and low T, and > at high T and low P. Along the equilibrium boundary the Gibbs Free energies of the reactants and products are equal and the Gibbs Free energy of reaction rG, is zero. Shortcutting H and S and Finding G Directly Like other thermodynamic potentials, we can write the change in Gibbs free energy of reaction as rG° = fG°reactants- fG°products Instead of using fH° and fS°, it is often possible to obtain fG° values for most compounds from electronic data bases. For example, if the following Gibbs free energies of formation are known: fG°CaSO4 = -1707.280 kJ/mol 2H2O fG°CaSO4 = -1321.790 kJ/mol fG°H2O = -237.129 kJ/mol
  • 53.
    then for CaSO4 + 2H2O = CaSO4 2H2O rG° = -1.232 kJ/mol Gibbs Free Energy at Any Pressure and Temperature We know many ways to determine rG at STP--but how do we calculate rG for other pressures and temperatures? Recall that the changes in Gibbs free energy with pressure and temperature are given by two of Maxwell's relations = rV and =- rS If we recast these as = rV P and =- rS T and integrate, we get rGdP = rGP - rGPref = rVdP or rGP = rGPref + rVdP and rGdT = rGT - rGTref =- rSdT or rGT = rGTref - rSdT thus rGPT = rGPrefTref + rVdP - rSdT Solving the Pressure Integral at Constant Temperature To a first approximation, we can ignore the expansivity and compressibility of solids and use
  • 54.
    rVsdP = rVs(P - 1) as a simplification. Don't forget that this approximation is valid for solids only! An even more common assumption for P>>1 is rVsdP = rVsP For example, calculate the change in Gibbs free energy for the reaction 2 jadeite = albite + nepheline if pressure increases from 1 bar to 10 kbar, given nepheline = 54.16 cm3 3 albite = 100.43 cm 3 jadeite = 60.40 cm First we calculate rV and find r = nepheline + albite -2 jadeite = 33.79 cm3 = 3.379 J/bar and thus rGPT - rG1,T = rVsP = 33.79 kJ/mol Solving the Temperature Integral at Constant Pressure Recall that the effect of temperature on the entropy change of reaction rS depends on the heat capacity change of reaction rCP: rS = dT Thus rGT = rGTref - rSdT expands to rGT = rGTref - STref + dT dT If the form of the heat capacity expansion is
  • 55.
    CP = a+ bT + cT-2 + dT-0.5 then the above double integral is a(T - T ln T) - bT2/2 - cT-1/2 + 4 dT0.5 - aTref - bTref2/2 + cTref-1 - 2 dTref0.5 + aTlnTref + bTTref - cTTref-2/2 - 2 dTTref-0.5 - T rSTref + Tref rSTref Note that this considers only vibrational entropy and ignores configurational entropy. This means of solving for rG requires that you know rG at the reference temperature. An alternative path that requires that you know the enthalpy change rH at the reference temperature is rGT = rHTref + CPdT - T rSTref + dT Solving the Temperature and Pressure Integrals for rGP,T To calculate the Gibbs free energy change of a reaction at any pressure and temperature, we can use either of the following equations, depending on whether we know rH or rG rGP,T = rG1,Tref - rSTref + dT dT + rVsP rGP,T = rH1,Tref + CPdT - T rSTref + dT + rVsP If you don't have heat capacity data for the reaction of interest, these equations can be roughly approximated as rGP,T = rG1,Tref - rS1,Tref(T - Tref) + rVsP rGP,T = rH1,Tref - T rS1,Tref + rVsP For example, calculate rG for jadeite + quartz = albite at 800 K and 20 kbar. The data at 298 K and 1 bar are rH° = 15.86 kJ/mol -1 -1 rS° = 51.47 J K mol 3 rVs° = 1.7342 J/bar = 17.342 cm /mol Using rGP,T = rH1,Tref - T rS1,Tref + rVsP = 15,860 - 800 * 51.47 + 1.7342 * 20,000 = 9.37 kJ/mol If we had used the complete equation for solids, integrating the heat capacities, we would have obtained an answer of 9.86 kJ/mol--not horrifically different.
  • 56.
    Calculating the PTPosition of a Reaction If we say that rG = 0 at equilibrium, then we can write our solids-only and constant-heat-capacity approximations as 0= rG1,T - rS1,Tref(T - Tref) + rVsP 0= rH1,Tref -T rS1,Tref + rVsP and thus we can calculate the pressure of a reaction at different temperatures by P= rG1,Tref - rS1,Tref(T - Tref) /- rVs P= rH1,Tref -T rS1,Tref /- rVs and we can calculate the temperature of a reaction at different pressures by T = Tref + rG1,Tref + rVsP / rS1,Tref T = Tref + rH1,Tref + rVsP / rS1,Tref Let's do this for the albite = jadeite + quartz reaction at T = 400 K and T = 1000 K: P = (15,860 - 5147 * 400) / -1.7342 = 2.7 kbar P = (15,860 - 5147 * 1000) / -1.7342 = 20.6 kbar Assuming that dP/dT is constant (a bad assumption, we know), the reaction looks like this Introduction to the Equilibrium Constant A bit farther down the road we will encounter a monster called the equilibrium constant K: K = exp(- rG°/RT)
  • 57.
    or ln K = - rG°/RT At equilibrium, where rG°= 0, ln K = 0 and K = 1. Let's see what K looks like for jadeite + quartz = albite at 800 K and 20 kbar: ln K = - ( rH1,Tref - T rSTref + rVsP)/ RT = -(15,860 - 800 * 51.47 + 1.7342 * 20,000)/(8.314*800) = -1.4 If we do this for all of PT space, we can contour PT space in terms of lnK: Solutions
  • 58.
    Almost no phasesare pure, but typically are mixtures of components. For example, olivine varies from pure forsterite Mg2SiO4 to pure fayalite Fe2SiO4, and can have any composition in between--it is a solid solution. We need a way to calculate the thermodynamic properties of such solutions. As a measure of convenience, we use mole fraction to describe the compositions of phases that are solid solutions. For example, a mix of 1 part forsterite and 3 parts fayalite yields an olivine with 25 mol% forsterite and 75 mol% fayalite, which can be written as (Mg0.25Fe0.75)2SiO4 or fo25fa75, etc. Mole fractions are denoted as Xi. We need a way of splitting up the Gibbs free energy of a phase among the various components of the phase--how for example do we decide how much of the Gibbs free energy of an olivine is related to the forsterite component and how much derives from the fayalite component? Likewise, how does the Gibbs free energy of a phase vary with composition--is the relationship linear between endmembers?? We address these issues by defining a partial Gibbs free energy for each component at constant pressure and temperature and constant composition of other components, called the partial molar Gibbs free energy or chemical potential i = where n is the amount of substance. For olivine solid solution composed of fayalite and forsterite components or endmembers, we write dG = dnfayalite + dnforsterite Volume of Mixing Imagine that mole fractions of phase A and phase B with molar volumes VA and VB, are mixed together. We can describe the volume of the mixture as V = XAVA° + XBVB° and it is a linear mixing of the two endmember volumes. We call this ideal mixing or mechanical mixing. Real solutions, however, do not behave this way, and the mixing is always non ideal, although sometimes only weakly so. The figure shows mixing that produces a smaller volume than expected, but it is not possible to predict the shapes and positions of such mixing curves.
  • 59.
    Partial Molar Volume Thepartial molar volume is defined as i If you mix two compounds A and B together and find a volume of mixing that is non-ideal, how can you determine the contribution that A and B each make to the volume? That is, what are the partial molar volumes of A and B, A and B?? Graphically, the partial molar volumes are the A and B axis intercepts of the tangent to the mixing curve, and can be described by the simple relationship: Vmix = XA A + XB B or Vmix = Xi i The behavior of this function is such that when XA is 1, Vmix = VA and when XA is 0, Vmix = VB. Alternatively,
  • 60.
    A = (Vmix - XB B) / XA Entropy of Mixing The entropy of mixing is never zero because mixing increases entropy. As we discussed days ago, the entropy of mixing (i.e., the configurational entropy) is Smix = -R (Xi ln Xi) where i = 1..n is the number of sites over which mixing is occurring. Enthalpy of Mixing Enthalpies also do not combined ideally (linearly) in mixtures because the mixture may have stronger bonds than were present in either of the unmixed phases. The excess enthalpy is Hmix = 0.5 * N z XAXB [2 AB - AA - BB] where AB is the interaction energy among A-B atoms, AA is the interaction energy among A-A atoms, and BB is the interaction energy among B-B atoms. Gibbs Free Energy of Mixing Recall that all spontaneous processes/reactions occur because of a decrease in Gibbs free energy. It should therefore not surprise you that the Gibbs free energy of mixing is always negative--otherwise mixing would not occur. The fact that A < G°A and B < G°B illustrates why compounds combine spontaneously--each compound is able to lower its free energy.
  • 61.
    The above figureis hypothetical because we cannot measure or calculate the absolute Gibbs free energy of phases. For this reason, is always expressed as a difference from some standard state measurement, as , - °, or - G°. The difference between the absolute Gibbs free energy G° per mole ° of a pure compound and the chemical potential per mole of dissolved compound is A - G°A = A - °A = RT lnXA This function has the following shape:
  • 62.
    implying that whenthe mineral is pure (X = 1) then = 0, and when the mineral is infinitely dilute (X = 0) then the chemical potential is undefined. For example, in a two-component mineral if XA = 0.4, at T = 298 K, A- °A = 8.314 * 298 ln 0.4 = -2271 J B- °B = 8.314 * 298 ln 0.6 = -1266 J The equation of the Gmix line is the sum of the chemical potentials of the endmembers: Gmix = RT (XA ln XA + XB ln XB) or Gmix = RT (Xi ln Xi) which looks like this for two components: Actually, all this discussion has been predicated on the assumption that Hmix = 0. If this is not true, Gmix is not a simple function of composition, but has the general form:
  • 63.
    Depending on therelative values of Hmix and -T Smix, the free energy of mixing may be negative throughout the whole composition range if the entropic energy contribution outweighs the enthalpy increase; this is more likely at higher temperature. The two free energy minima in the above figure indicate that minerals of intermediate compositions can reduce their free energy by unmixing into two phases. This explains the appearance and driving force for exsolution. Note that this can only be true if Hmix > 0, i.e., if 2 AB > AA + BB, which makes sense because it means that the A-B bonds have a higher free energy than the sum of the free energies of separate AA and BB bonds. Activities In reality, no phases behave ideally--that is, their chemical potentials are never simple logarithmic functions of composition as A - °A = RT lnXA implies. Instead, we say that the chemical potential is a simple logarithmic function of activity and define activity as a = ( X) where a is the activity of a compound, is the "site occupancy coefficient" (e.g., = 2 for Mg in Mg2SiO4), and is the activity coefficient that describes the non-ideal behavior. Thus we write A - °A = RT lnaA For pure compounds a=1 because X=1. For ideal compounds =1. As a specific example, the chemical potential of the almandine (Fe3Al2Si3O12) component of a garnet solid solution ((Fe, Mg, Ca, Mn)3Al2Si3O12) is alm = °alm + RT lnXalm
  • 64.
    To be clear,° is the chemical potential of the component in its pure reference state and varies as a function of pressure and temperature; this we measure with calorimetry. is the chemical potential as it actually occurs and varies as a function of phase composition; this we measure with an electron microprobe. The activity forms a bridge between idealized behavior and real behavior. The Equilibrium Constant At equilibrium the sum of the Gibbs free energies of the reactants equals the sum of the Gibbs free energies of the products. Equally, the sum of the partial molar Gibbs free energies (chemical potentials) of the reactants equals the sum of the partial molar Gibbs free energies (chemical potentials) of the products. In other words, for SiO2 + 2H2O = H4SiO4 at equilibrium, H4SiO4 = SiO2 + 2 H2O More generally, for aA + bB = cC + dD then c C+d D=a A+b B or, at equilibrium r =0=c C+d D-a A-b B which we can reformat as r = i i where i is the stochiometric coefficient of a product or reactant and is positive if for a product and negative if for a reactant. If we then remember that - ° = RT lna and rewrite it as = ° + RT lna we can reformat the earlier equation as
  • 65.
    r = 0 = c( C° + RT lnaC) + d( D° + RT lnaD) - a( A° + RT lnaA) - b( B° + RT lnaB) which looks nicer as r = r ° + RT ln (aCc aDd/aAa aBb) To be completely general we write r = r ° + RT ln ai ( means to multiply all i terms) This equation is invariably simplified to r = r ° + RT lnQ and Q is the activity product ratio. The activities in the Q term change as the reaction progresses toward equilibrium. To be clear again, r ° is the difference in the Gibbs free energies of the products and reactants when each is in its pure reference state and varies as a function of pressure and temperature. r is the difference in the Gibbs free energies of the products and reactants as they actually occur and varies as a function of phase composition. At equilibrium, the product and reactant activities have adjusted themselves such that r = 0. We write this (with K instead of Q, to signify equilibrium) as 0= rG° = -RT ln K K is called the equilibrium constant. If K is very large (ln K positive), the combined activities of the reaction products are enormous relative to the combined activities of the reactants and the reaction will likely progress. On the other hand, if K is small (ln K negative), there is unlikely to be any reaction. The utility of K is that it tells us for any reaction and any pressure and temperature, what the activity ratios of the phases will be at equilibrium. For example, for the reaction albite = jadeite + quartz let's say that at a particular P and T, rG° = -20.12 kJ/mol Using rG° = -RT lnK we calculate
  • 66.
    log K =3.52 This means that at equilibrium, (ajadeite aquartz / aNaAlSi3O8) = e3.52 Where ajadeite is the activity of NaAlSi2O6 in clinopyroxene and aalbite is the activity of NaAlSi3O8 in plagioclase. Alternative Route to the Equilibrium Constant When we think of mass balance in a reaction, we can explicitly write 0= iMi where i are the stoichiometric coefficients and Mi are the masses or the phase components. Analogously, we can explicitly write a similar balance among the chemical potentials: 0= i i For each chemical potential we can write i= °i + RT lnai Combining these two equations we find 0= i °i + iRTln ai 0= i °i + RTln (ai) 0= i °i + RTln ai 0= i °i + RTln K and eventually 0= rG° + RT ln K or rG° = -RT ln K The equation K= ai
  • 67.
    is the lawof mass action (which actually discusses the action of chemical potential rather than mass). We can also write for 298 K and 1 atm rH° -T rS° = - RT ln K and for any P and T of interest: rH1,Tref + CPdT - T rSTref + dT + rVP = - RT ln K This has been called "the most important equation in thermodynamics," so you'd better like it(!) The equilibrium constant K is a function of 1/T -ln K = ( rG° / RT) = [( rH / RT) - ( rS / R)] Which looks like Activity Models (Activity-Composition Relations) for Crystalline Solutions Garnets are solid solutions of component abbrev. Formula pyrope prp Mg3Al2Si3O12 almandine alm Fe3Al2Si3O12 grossular grs Ca3Al2Si3O12 spessartine sps Mn3Al2Si3O12 andradite and Ca3Fe23+Si3O12 Mixing models derive from entropy considerations. In particular the relation
  • 68.
    Smix = -R Xi ln Xi although we will not go through the derivation. Mixing on a Single Site The simplest type of useful activity model is the ionic model, wherein we assume that mixing occurs on crystallographic sites. For a Mg-Fe-Ca-Mn garnet with mixing on one site, which we can idealize as (A,B,C,D) Al2Si3O12, the activities are 3 3 aprp = Mg XMg 3 3 aalm = Fe XFe 3 3 agrs = Ca XCa 3 3 asps = Mn XMn The pyrope activity is shown in the above figure. In general, for ideal mixing in a mineral with a single crystallographic site that can contain ions, ai = Xj where a, the activity of component i, is the mole fraction of element j raised to the power. For non- ideal mixing, we include an activity coefficient ai = j Xj Mixing on a Several Sites For minerals with two distinct sites and the general formula (A,B) (Y,Z)
  • 69.
    there are fourpossible end member components A Y , A Z , B Y , and B Z . The ideal activities of these components are aA Y = XA XY aA Z = XA XZ aB Y = XB XY aB Z = XB XZ For non-ideal garnet activities we write aprp = XMg3 XAl2 or Mg3 XMg3 Al2 XAl2 aalm = XFe3 XAl2 or Fe3 XFe3 Al2 XAl2 agrs = XCa3 XAl2 or Ca3 XCa3 Al2 XAl2 asps = XMn3 XAl2 or Mn3 XMn3 Al2 XAl2 aand = XCa3 XFe3+2 or Ca3 XMn3 Fe3+2 XFe3+2 where the X3 term describes mixing on the 8-fold trivalent site and the X2 term describes mixing on the octahedral divalent site. The pyrope activity is shown in the above figure for Mg from 0 3 and Al from 0 2. It is common to modify such models that are based on completely random mixing of elements with models that consider local charge balance on certain sites or the Al-avoidance principle. Geothermometry and Geobarometry Exchange Reactions Many thermometers are based on exchange reactions, which are reactions that exchange elements but preserve reactant and product phases. For example:
  • 70.
    Fe3Al2Si3O12 + KMg3AlSi3O10(OH)2 = Mg3Al2Si3O12 + KFe3AlSi3O10(OH)2 almandine + phlogopite = pyrope + annite We can reduce this reaction to a simple exchange vector: (FeMg)gar+1 = (FeMg)bio-1 Popular thermometers include garnet-biotite (GARB), garnet-clinopyroxene, garnet-hornblende, and clinopyroxene-orthopyroxene; all of these are based on the exchange of Fe and Mg, and are excellent thermometers because rV is small, such that = is large (i.e., the reactions have steep slopes and are little influenced by pressure). Let's write the equilibrium constant for the GARB exchange reaction K = (aprpaann)/(aalmaphl) thus rG = -RT ln (aprpaann)/(aalmaphl) This equation implies that the activities of the Fe and Mg components of biotite and garnet are a function of Gibbs free energy change and thus are functions of pressure and temperature. If we assume ideal behavior ( = 1) in garnet and biotite and assume that there is mixing on only 1 site aalm = Xalm3 = [Fe/(Fe + Mg + Ca + Mn)]3 aprp = Xprp3 = [Mg/(Fe + Mg)]3 aann = Xann3 = [Fe/(Fe + Mg)]3 aphl = Xphl3 = [Mg/(Fe + Mg)]3 Thus the equilibrium constant is K = (XMggar XFebio)/(XFegar XMgbio) When discussing element partitioning it is common to define a distribution coefficient KD, which is just the equilibrium constant without the exponent (this just describes the partitioning of elements and not the partitioning of chemical potential): KD = (XMggar XFebio)/(XFegar XMgbio) = (Mg/Fe)gar /(Mg/Fe)bio = K1/3
  • 71.
    Long before mostof you were playground bullies (1978) a couple of deities named John Ferry and Frank Spear measured experimentally the distribution of Fe and Mg between biotite and garnet at 2 kbar and found the following relationship: If you compare their empirical equation ln KD = -2109 / T + 0.782 this immediately reminds you of ln K = - ( rG° / RT) = -( rH / RT) - (P rV / RT) + ( rS / R) and you realize that for this reaction rS = 3*0.782*R = 19.51 J/mol K (the three comes from the site occupancy coefficient; i.e., K = KD3) and -( rH / R) - (P rV / R) = -2109 or rH = 3*2109*R -2070* rV Molar volume measurements show that for this exchange reaction rV = 0.238 J/bar, thus rH = 52.11 kJ/mol The full equation is then
  • 72.
    52,110 - 19.51*T(K)+ 0.238*P(bar) + 3RT ln KD = 0 To plot the KD lines in PT space Net-Transfer Reactions Net-transfer reactions are those that cause phases to appear or disappear. Geobarometers are often based on net-transfer reactions because rV is large and relatively insensitive to temperature. A popular one is GASP: 3CaAl2Si2O8 = Ca3Al2Si3O12 + 2Al2SiO5 + SiO2 anorthite = grossular + kyanite + quartz which describes the high-pressure breakdown of anorthite. For this reaction rG = -RT ln [(aqtzaky2agrs) / aan3] = -RT ln agrs / aan3 (the activities of quartz and kyanite are one because they are pure phases). A best fit through the experimental data for this reaction by Andrea Koziol and Bob Newton yields P(bar) = 22.80 T(K) - 7317 for rV = -6.608 J/bar. Again, if we use
  • 73.
    ln K =-( rH / RT) - (P rV / RT) + ( rS / R) and set ln K = 0 to calculate values at equilibrium, we can rewrite the above as (P rV / R) = -( rH / R) + (T rS / R) or P=T rS / rV - rH / rV if T rS / rV = 22.8 then rS = -150.66 J/mol K if rH / rV = 7317 then rH = -48.357 kJ/mol So, we can write the whole shmear as 0 = -48,357 + 150.66 T(K) -6.608 P (bar) + RT ln K Contours of ln K on a PT diagram for GASP look like this: Kinetics Thermodynamics places no constraints on the rate or mechanism of reaction--that is the realm of kinetics. A popular method for describing the rate at which reactions proceed is to talk of an activated state through which the reaction must pass:
  • 74.
    When a systempasses from an initial to a final state it must overcome an activation energy barrier G*. The advantages of this activation energy barrier paradigm are that it qualitatively explains the i) persistence of metastable states; ii) effect of catalysts in lowering G*; iii) temperature dependence of transformation. We can draw a similar diagram for a change in enthalpy induced by the reaction rH and an activation enthalpy barrier H* (usually called an activation energy Q*). Of course, unlike rG, rH can be positive or negative: It is not easy to generalize about the activation entropy S*, however, in general, reactions with positive entropy change rS are faster. For example, evaporation is faster than condensation, melting is faster than crystallization, and disordering is faster than ordering. Because thermal energy dictates whether an atom has sufficient energy to overcome an activation energy barrier, we will write that the fraction of atoms with thermal energy greater than H* is f = exp ( - H*/RT)
  • 75.
    i.e., if f<< 1, few atoms have enough thermal energy to overcome the activation energy barrier, whereas if f = 1 all atoms can overcome the activation energy barrier. For reactions that involve a single step characterized by a single activation energy, the rate of the reaction depends on the i) frequency with which atoms attempt to jump from one site to the next ; ii) fraction of atoms with thermal energy greater than Q*; and iii) probability p that the atom jumping satisfies some geometrical consideration (this is a fancy name for a fudge factor): rate p exp(-Q*/RT) Often this is rewritten as rate (kT/h) exp(-Q*/RT) where k is Boltzmann's constant, and h is Planck's constant. Thus, the rate at which atoms jump is related to temperature and to atom-scale processes described by k and h. Nucleation Most transformations take place by nucleation and growth. The driving force for nucleation results from the fact that the formation of the new phase lowers the total free energy by VG, the Gibbs free energy change of reaction per unit volume. Nucleation is opposed by an interfacial energy and a strain energy . The overall change in nucleation energy for a spherical nucleus of radius r is then nG = VG + Ginterfacial + Gstrain = (4/3) r3 VG + 4 r2 + (4/3) r3 These different energy contributions yield an increase in total free energy up to a certain radius termed the critical radius, beyond which the total free energy decreases.
  • 76.
    This change fromincreasing to decreasing nucleation free energy happens because the surface:volume ratio decreases with increasing radius, so the negative volume free energy term that favors nucleation eventually overwhelms the positive surface and strain free energy terms that oppose nucleation. We can re-order the terms in the above equation to calculate the critical size of the nucleus rc rc = -2 /( VG + ) If, at the critical radius, nG = G*, the activation energy for nucleation is 3 G* = 16 / 3( VG + )2 Growth Following nucleation, grains of the product phase(s) grow to replace the parent phase(s). Either the reaction is polymorphic, or atoms of the parent phase must dissolve, be transported, and then attach themselves to the product phase. The rate of growth is thus controlled by the rate of the slowest of these three steps, and is described as either interface controlled or diffusion controlled. Turnbull's (1956) formulation to quantify interface-controlled growth rate is: = (kT/h) exp( -Q*/RT)[( - rG/RT)] where is an "interface jump distance" and the rest you will recognize from previous equations. The [( - rG/RT)] term indicates that the rate of growth depends on the Gibbs free energy change of reaction. As rG 0, this term also approaches zero. As rG , this term approaches 1. Transformation: Nucleation + Growth
  • 77.
    A complete transformationinvolves nucleation and growth--the product phases must form and grow and the parent phases must be consumed. The letter _ is often used to indicate 'reaction progress' or 'degree of transformation,' and varies from 0 (no reaction) to 1 (complete reaction). The transformation is the time-integrated result of ongoing nucleation and growth, which can vary in time and space: = 1 - exp[(4/3) dt] Just as an example, the general rate equation for interface-controlled (i.e., not diffusion-controlled) growth of nuclei formed on grain boundaries is 2 = 1 - exp{(6.7/d) [1-exp( [ (t - )2 - y2] d )] dy} In their simplest form, these equations have the form = 1 - exp(-ktn) Flip this around to exp(-ktn) = 1 - linearize by means of logarithms -ktn = ln (1 - ) change signs and cleverly insert ln 1 ktn = ln 1 - ln (1 - ) rewrite the two logarithms as one, recalling that ln (a/b) = ln a - ln b ktn = ln [1 / (1 - )] and linearize once more with logarithms to get the final glorious equation n ln t + ln k = ln [ ln (1 - )] The Last Supper: A Still Life of Thermodynamics & Kinetics Zeolites, like laumontite and wairakite, form in oil fields as alteration products of plagioclase and other Ca-bearing phases. The thermodynamic properties ( H, S, V, CP) of zeolites have been measured, and we can use those properties to calculate a phase diagram for the CASH system:
  • 78.
    Laumontite is thephase that is stable at the lowest P and T. Wairakite is the next phase to form, and it does so via the reaction laumontite _ wairakite + H2O. At higher temperature wairakite + H2O decompose to anorthite + quartz + H2O. Kinetic experiments conducted on the reaction laumontite _ wairakite + H2O, using crystals of laumontite suspended in H2O, reveal the transformation vs. time data in the figure above. One could use the equation to interpret the two sub-figures to reveal different n and k values for each temperature. This is the way rate data were interpreted in the bad old days, but this approach lacks any physical or mechanistic basis. Instead, we can measure the rate of growth at each temperature and relate the rate of growth to the Turnbull equation. Above is an example of grain growth data collected for 450°C. The rate of growth is interpreted to be a constant 2.0 ± 0.3 E-10 m/s. If growth rate data like this can be collected for every temperature of interest, an activation energy for growth can be calculated: The activation energy for growth apparently varies from ~196 kJ/mol to ~ 72 kJ/mol depending on the reaction mechanism. The growth rate data can be combined with similar nucleation rate data to yield a complete transformation rate equation that can be extrapolated to geologic conditions of interest. The figure below shows extrapolated growth rates (m/s) for the laumontite _ wairakite + H2O reaction. search Potentials Free energy · Free entropy Internal energy U(S,V) Enthalpy H(S,p) = U + pV Helmholtz free energy A(T,V) = U − TS Gibbs free energy G(T,p) = H − TS The four laws of thermodynamics define fundamental physical quantities (temperature, energy, and entropy) that characterize thermodynamic systems. The laws describe how these quantities behave under various circumstances, and forbid certain phenomena (such as perpetual motion). The four laws of thermodynamics are:[1][2][3][4][5][6]
  • 79.
    Zeroth law ofthermodynamics: If two systems are in thermal equilibrium with a third system, they must be in thermal equilibrium with each other. This law helps define the notion of temperature. First law of thermodynamics: Heat and work are forms of energy transfer. Energy is invariably conserved but the internal energy of a closed system changes as heat and work are transferred in or out of it. Equivalently, perpetual motion machines of the first kind are impossible. Second law of thermodynamics: The entropy of any isolated system not in thermal equilibrium almost always increases. Isolated systems spontaneously evolve towards thermal equilibrium—the state of maximum entropy of the system—in a process known as "thermalization". Equivalently, perpetual motion machines of the second kind are impossible. Third law of thermodynamics: The entropy of a system approaches a constant value as the temperature approaches zero. The entropy of a system at absolute zero is typically zero, and in all cases is determined only by the number of different ground states it has. Specifically, the entropy of a pure crystalline substance at absolute zero temperature is zero. Classical thermodynamics describes the exchange of work and heat between systems. It has a special interest in systems that are individually in states of thermodynamic equilibrium. Thermodynamic equilibrium is a condition of systems which are adequately described by only macroscopic variables. Every physical system, however, when microscopically examined, shows apparently random microscopic statistical fluctuations in its thermodynamic variables of state (entropy, temperature, pressure, etc.). These microscopic fluctuations are negligible for systems which are nearly in thermodynamic equilibrium and which are only macroscopically examined. They become important, however, for systems which are nearly in thermodynamic equilibrium when they are microscopically examined, and, exceptionally, for macroscopically examined systems that are in critical states,[7] and for macroscopically examined systems that are far from thermodynamic equilibrium. There have been suggestions of additional laws, but none of them achieve the generality of the four accepted laws, and they are not mentioned in standard textbooks.[1][2][3][4][5][8][9] The laws of thermodynamics are important fundamental laws in physics and they are applicable in other natural sciences. Table of Contents 1 Zeroth law 2 First law 3 Second law 4 Third law 5 History 6 See also 7 References 8 Further reading Zeroth law
  • 80.
    The zeroth lawof thermodynamics may be stated as follows: If system A and system B are individually in thermal equilibrium with system C, then system A is in thermal equilibrium with system B The zeroth law implies that thermal equilibrium, viewed as a binary relation, is a Euclidean relation. If we assume that the binary relationship is also reflexive, then it follows that thermal equilibrium is an equivalence relation. Equivalence relations are also transitive and symmetric. The symmetric relationship allows one to speak of two systems being "in thermal equilibrium with each other", which gives rise to a simpler statement of the zeroth law: If two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other However, this statement requires the implicit assumption of both symmetry and reflexivity, rather than reflexivity alone. The law is also a statement about measurability. To this effect the law allows the establishment of an empirical parameter, the temperature, as a property of a system such that systems in equilibrium with each other have the same temperature. The notion of transitivity permits a system, for example a gas thermometer, to be used as a device to measure the temperature of another system. Although the concept of thermodynamic equilibrium is fundamental to thermodynamics and was clearly stated in the nineteenth century, the desire to label its statement explicitly as a law was not widely felt until Fowler and Planck stated it in the 1930s, long after the first, second, and third law were already widely understood and recognized. Hence it was numbered the zeroth law. The importance of the law as a foundation to the earlier laws is that it allows the definition of temperature in a non-conjugate variable. First law The first law of thermodynamics may be stated thus: Increase in internal energy of a body = heat supplied to the body - work done by the body. U = Q -W
  • 81.
    For a thermodynamiccycle, the net heat supplied to the system equals the net work done by the system. More specifically, the First Law encompasses several principles: The law of conservation of energy. This states that energy can be neither created nor destroyed. However, energy can change forms, and energy can flow from one place to another. The total energy of an isolated system remains the same. The concept of internal energy and its relationship to temperature. If a system, for example a rock, has a definite temperature, then its total energy has three distinguishable components. If the rock is flying through the air, it has kinetic energy. If it is high above the ground, it has gravitational potential energy. In addition to these, it has internal energy which is the sum of the kinetic energy of vibrations of the atoms in the rock, and other sorts of microscopic motion, and of the potential energy of interactions between the atoms within the rock. Other things being equal, the internal energy increases as the rock's temperature increases. The concept of internal energy is the characteristic distinguishing feature of the first law of thermodynamics. The flow of heat is a form of energy transfer. In other words, a quantity of heat that flows from a hot body to a cold one can be expressed as an amount of energy being transferred from the hot body to the cold one. Performing work is a form of energy transfer. For example, when a machine lifts a heavy object upwards, some energy is transferred from the machine to the object. The object acquires its energy in the form of gravitational potential energy in this example. Combining these principles leads to one traditional statement of the first law of thermodynamics: it is not possible to construct a perpetual motion machine which will continuously do work without consuming energy. Second law The second law of thermodynamics asserts the existence of a quantity called the entropy of a system and further states that When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself (but not necessarily in equilibrium with each other at first) are at some time allowed to interact, breaking the isolation that separates the two systems, allowing them to exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final combination of exchanging systems. In the process of reaching a new thermodynamic equilibrium, total entropy has increased, or at least has not decreased. It follows that the entropy of an isolated macroscopic system never decreases. The second law states that spontaneous natural processes increase entropy overall, or in another formulation that heat can
  • 82.
    spontaneously be conductedor radiated only from a higher-temperature region to a lower-temperature region, but not the other way around. The second law refers to a wide variety of processes, reversible and irreversible. Its main import is to tell about irreversibility. The prime example of irreversibility is in the transfer of heat by conduction or radiation. It was known long before the discovery of the notion of entropy that when two bodies of different temperatures are connected with each other by purely thermal connection, conductive or radiative, then heat always flows from the hotter body to the colder one. This fact is part of the basic idea of heat, and is related also to the so-called zeroth law, though the textbooks' statements of the zeroth law are usually reticent about that, because they have been influenced by Carathéodory's basing his axiomatics on the law of conservation of energy and trying to make heat seem a theoretically derivative concept instead of an axiomatically accepted one. Šilahvý (1997) notes that Carathéodory's approach does not work for the description of irreversible processes that involve both heat conduction and conversion of kinetic energy into internal energy by viscosity (which is another prime example of irreversibility), because "the mechanical power and the rate of heating are not expressible as differential forms in the 'external parameters'". [10] The second law tells also about kinds of irreversibility other than heat transfer, and the notion of entropy is needed to provide that wider scope of the law. According to the second law of thermodynamics, in a reversible heat transfer, an element of heat transferred, δQ, is the product of the temperature (T), both of the system and of the sources or destination of the heat, with the increment (dS) of the system's conjugate variable, its entropy (S) View formula on Wikipedia[1] The second law defines entropy, which may be viewed not only as a macroscopic variable of classical thermodynamics, but may also be viewed as a measure of deficiency of physical information about the microscopic details of the motion and configuration of the system, given only predictable experimental reproducibility of bulk or macroscopic behavior as specified by macroscopic variables that allow the distinction to be made between heat and work. More exactly, the law asserts that for two given macroscopically specified states of a system, there is a quantity called the difference of entropy between them. The entropy difference tells how much additional microscopic physical information is needed to specify one of the macroscopically specified states, given the macroscopic specification of the other, which is often a conveniently chosen reference state. It is often convenient to presuppose the reference state and not to explicitly state it. A final condition of a natural process always contains microscopically specifiable effects which are not fully and exactly predictable from the macroscopic specification of the initial condition of the process. This is why entropy increases in natural processes. The entropy increase tells how much extra microscopic information is needed to tell the final macroscopically specified state from the initial macroscopically specified state.[11] Third law The third law of thermodynamics is sometimes stated as follows: The entropy of a perfect crystal at absolute zero is exactly equal to zero. At zero temperature the system must be in a state with the minimum thermal energy. This statement holds true if the perfect crystal has only one state with minimum energy. Entropy is related to the number of possible microstates according to S = kBln(Ω), where S is the entropy of the system, kB Boltzmann's constant, and Ω the number of microstates (e.g. possible configurations of atoms). At absolute zero there is only 1 microstate possible (Ω=1) and ln(1) = 0.
  • 83.
    A more generalform of the third law that applies to systems such as glasses that may have more than one minimum energy state: The entropy of a system approaches a constant value as the temperature approaches zero. The constant value (not necessarily zero) is called the residual entropy of the system. History See also: Philosophy of thermal and statistical physics Count Rumford (born Benjamin Thompson) showed, about 1797, that mechanical action can generate indefinitely large amounts of heat, so challenging the caloric theory. The historically first established thermodynamic principle which eventually became the second law of thermodynamics was formulated by Sadi Carnot during 1824. By 1860, as formalized in the works of those such as Rudolf Clausius and William Thomson, two established principles of thermodynamics had evolved, the first principle and the second principle, later restated as thermodynamic laws. By 1873, for example, thermodynamicist Josiah Willard Gibbs, in his memoir Graphical Methods in the Thermodynamics of Fluids, clearly stated the first two absolute laws of thermodynamics. Some textbooks throughout the 20th century have numbered the laws differently. In some fields removed from chemistry, the second law was considered to deal with the efficiency of heat engines only, whereas what was called the third law dealt with entropy increases. Directly defining zero points for entropy calculations was not considered to be a law. Gradually, this separation was combined into the second law and the modern third law was widely adopted. ENERGY TRASFORMATION Laws of Thermodynamics Process functions: Work · Heat Material properties T Specific heat capacity c = N Compressibility β=−1
  • 84.
    V ∂p 1 Thermal expansion α= V · Free entropy Internal energy U(S,V) Enthalpy H(S,p) = U + pV Helmholtz free energy A(T,V) = U − TS Gibbs free energy G(T,p) = H − TS The four laws of thermodynamics define fundamental physical quantities (temperature, energy, and entropy) that characterize thermodynamic systems. The laws describe how these quantities behave under various circumstances, and forbid certain phenomena (such as perpetual motion). The four laws of thermodynamics are:1][2][3][4][5][6] Zeroth law of thermodynamics: If two systems are in thermal equilibrium with a third system, they must be in thermal equilibrium with each other. This law helps define the notion of temperature. First law of thermodynamics: Heat and work are forms of energy transfer. Energy is invariably conserved but the internal energy of a closed system changes as heat and work are transferred in or out of it. Equivalently, perpetual motion machines of the first kind are impossible. Second law of thermodynamics: The entropy of any isolated system not in thermal equilibrium almost always increases. Isolated systems spontaneously evolve towards thermal equilibrium—the state of maximum entropy of the system—in a process known as "thermalization". Equivalently, perpetual motion machines of the second kind are impossible. Third law of thermodynamics: The entropy of a system approaches a constant value as the temperature approaches zero. The entropy of a system at absolute zero is typically zero, and in all cases is determined only by the number of different ground states it has. Specifically, the entropy of a pure crystalline substance at absolute zero temperature is zero. Classical thermodynamics describes the exchange of work and heat between systems. It has a special interest in systems that are individually in states of thermodynamic equilibrium. Thermodynamic
  • 85.
    equilibrium is acondition of systems which are adequately described by only macroscopic variables. Every physical system, however, when microscopically examined, shows apparently random microscopic statistical fluctuations in its thermodynamic variables of state (entropy, temperature, pressure, etc.). These microscopic fluctuations are negligible for systems which are nearly in thermodynamic equilibrium and which are only macroscopically examined. They become important, however, for systems which are nearly in thermodynamic equilibrium when they are microscopically examined, and, exceptionally, for macroscopically examined systems that are in critical states,[7] and for macroscopically examined systems that are far from thermodynamic equilibrium. There have been suggestions of additional laws, but none of them achieve the generality of the four accepted laws, and they are not mentioned in standard textbooks.[1][2][3][4][5][8][9] The laws of thermodynamics are important fundamental laws in physics and they are applicable in other natural sciences. Zeroth law The zeroth law of thermodynamics may be stated as follows: If system A and system B are individually in thermal equilibrium with system C, then system A is in thermal equilibrium with system B The zeroth law implies that thermal equilibrium, viewed as a binary relation, is a Euclidean relation. If we assume that the binary relationship is also reflexive, then it follows that thermal equilibrium is an equivalence relation. Equivalence relations are also transitive and symmetric. The symmetric relationship allows one to speak of two systems being "in thermal equilibrium with each other", which gives rise to a simpler statement of the zeroth law: If two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other However, this statement requires the implicit assumption of both symmetry and reflexivity, rather than reflexivity alone. The law is also a statement about measurability. To this effect the law allows the establishment of an empirical parameter, the temperature, as a property of a system such that systems in equilibrium with each other have the same temperature. The notion of transitivity permits a system, for example a gas thermometer, to be used as a device to measure the temperature of another system. Although the concept of thermodynamic equilibrium is fundamental to thermodynamics and was clearly stated in the nineteenth century, the desire to label its statement explicitly as a law was not widely felt until Fowler and Planck stated it in the 1930s, long after the first, second, and third law were already widely understood and recognized. Hence it was numbered the zeroth law. The importance of the law as
  • 86.
    a foundation tothe earlier laws is that it allows the definition of temperature in a non-circular way without reference to entropy, its conjugate variable. First law The first law of thermodynamics may be stated thus: Increase in internal energy of a body = heat supplied to the body - work done by the body. U = Q - W For a thermodynamic cycle, the net heat supplied to the system equals the net work done by the system. More specifically, the First Law encompasses several principles: The law of conservation of energy. This states that energy can be neither created nor destroyed. However, energy can change forms, and energy can flow from one place to another. The total energy of an isolated system remains the same. The concept of internal energy and its relationship to temperature. If a system, for example a rock, has a definite temperature, then its total energy has three distinguishable components. If the rock is flying through the air, it has kinetic energy. If it is high above the ground, it has gravitational potential energy. In addition to these, it has internal energy which is the sum of the kinetic energy of vibrations of the atoms in the rock, and other sorts of microscopic motion, and of the potential energy of interactions between the atoms within the rock. Other things being equal, the internal energy increases as the rock's temperature increases. The concept of internal energy is the characteristic distinguishing feature of the first law of thermodynamics. The flow of heat is a form of energy transfer. In other words, a quantity of heat that flows from a hot body to a cold one can be expressed as an amount of energy being transferred from the hot body to the cold one. Performing work is a form of energy transfer. For example, when a machine lifts a heavy object upwards, some energy is transferred from the machine to the object. The object acquires its energy in the form of gravitational potential energy in this example. Combining these principles leads to one traditional statement of the first law of thermodynamics: it is not possible to construct a perpetual motion machine which will continuously do work without consuming energy. Second law
  • 87.
    The second lawof thermodynamics asserts the existence of a quantity called the entropy of a system and further states that When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself (but not necessarily in equilibrium with each other at first) are at some time allowed to interact, breaking the isolation that separates the two systems, allowing them to exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final combination of exchanging systems. In the process of reaching a new thermodynamic equilibrium, total entropy has increased, or at least has not decreased. It follows that the entropy of an isolated macroscopic system never decreases. The second law states that spontaneous natural processes increase entropy overall, or in another formulation that heat can spontaneously be conducted or radiated only from a higher-temperature region to a lower-temperature region, but not the other way around. The second law refers to a wide variety of processes, reversible and irreversible. Its main import is to tell about irreversibility. The prime example of irreversibility is in the transfer of heat by conduction or radiation. It was known long before the discovery of the notion of entropy that when two bodies of different temperatures are connected with each other by purely thermal connection, conductive or radiative, then heat always flows from the hotter body to the colder one. This fact is part of the basic idea of heat, and is related also to the so-called zeroth law, though the textbooks' statements of the zeroth law are usually reticent about that, because they have been influenced by Carathéodory's basing his axiomatics on the law of conservation of energy and trying to make heat seem a theoretically derivative concept instead of an axiomatically accepted one. Šilahvý (1997) notes that Carathéodory's approach does not work for the description of irreversible processes that involve both heat conduction and conversion of kinetic energy into internal energy by viscosity (which is another prime example of irreversibility), because "the mechanical power and the rate of heating are not expressible as differential forms in the 'external parameters'".[10] The second law tells also about kinds of irreversibility other than heat transfer, and the notion of entropy is needed to provide that wider scope of the law. According to the second law of thermodynamics, in a reversible heat transfer, an element of heat transferred, δQ, is the product of the temperature (T), both of the system and of the sources or destination of the heat, with the increment (dS) of the system's conjugate variable, its entropy (S) View formula on Wikipedia[1] The second law defines entropy, which may be viewed not only as a macroscopic variable of classical thermodynamics, but may also be viewed as a measure of deficiency of physical information about the microscopic details of the motion and configuration of the system, given only predictable experimental
  • 88.
    reproducibility of bulkor macroscopic behavior as specified by macroscopic variables that allow the distinction to be made between heat and work. More exactly, the law asserts that for two given macroscopically specified states of a system, there is a quantity called the difference of entropy between them. The entropy difference tells how much additional microscopic physical information is needed to specify one of the macroscopically specified states, given the macroscopic specification of the other, which is often a conveniently chosen reference state. It is often convenient to presuppose the reference state and not to explicitly state it. A final condition of a natural process always contains microscopically specifiable effects which are not fully and exactly predictable from the macroscopic specification of the initial condition of the process. This is why entropy increases in natural processes. The entropy increase tells how much extra microscopic information is needed to tell the final macroscopically specified state from the initial macroscopically specified state.[11] Third law The third law of thermodynamics is sometimes stated as follows: The entropy of a perfect crystal at absolute zero is exactly equal to zero. At zero temperature the system must be in a state with the minimum thermal energy. This statement holds true if the perfect crystal has only one state with minimum energy. Entropy is related to the number of possible microstates according to S = kBln(Ω), where S is the entropy of the system, kB Boltzmann's constant, and Ω the number of microstates (e.g. possible configurations of atoms). At absolute zero there is only 1 microstate possible (Ω=1) and ln(1) = 0. A more general form of the third law that applies to systems such as glasses that may have more than one minimum energy state: The entropy of a system approaches a constant value as the temperature approaches zero. The constant value (not necessarily zero) is called the residual entropy of the system. History See also: Philosophy of thermal and statistical physics Count Rumford (born Benjamin Thompson) showed, about 1797, that mechanical action can generate indefinitely large amounts of heat, so challenging the caloric theory. The historically first established thermodynamic principle which eventually became the second law of thermodynamics was formulated by Sadi Carnot during 1824. By 1860, as formalized in the works of those such as Rudolf Clausius and William Thomson, two established principles of thermodynamics had evolved, the first principle and the second principle, later restated as thermodynamic laws. By 1873, for example, thermodynamicist Josiah Willard Gibbs, in his memoir Graphical Methods in the Thermodynamics of Fluids, clearly stated the first two absolute laws of thermodynamics. Some textbooks throughout the 20th century have numbered the laws differently. In some fields removed from chemistry, the second law was considered to deal with the efficiency of heat engines only, whereas what was called the third law dealt with entropy increases.
  • 89.
    Directly defining zeropoints for entropy calculations was not considered to be a law. Gradually, this separation was combined into the second law and the modern third law was widely adopted. See also Conservation law Third law of thermodynamics Entropy production Heat death of the universe Laws of science Table of thermodynamic equations Ginsberg's Theorem References ↑ 1.0 1.1 1.2 Guggenheim, E.A. (1985). Thermodynamics. An Advanced Treatment for Chemists and Physicists, seventh edition, North Holland, Amsterdam, ISBN 0-444-86951-4. ↑ 2.0 2.1 Kittel, C. Kroemer, H. (1980). Thermal Physics, second edition, W.H. Freeman, San Francisco, ISBN 0-7167-1088-9. ↑ 3.0 3.1 Adkins, C.J. (1968). Equilibrium Thermodynamics, McGraw-Hill, London, ISBN 0-07-084057-1. ↑ 4.0 4.1 Kondepudi D. (2008). Introduction to Modern Thermodynamics, Wiley, Chichester, ISBN 978- 0-470-01598-8. ↑ 5.0 5.1 Lebon, G., Jou, D., Casas-Vázquez, J. (2008). Understanding Non-equilibrium Thermodynamics. Foundations, Applications, Frontiers, Springer, Berlin, ISBN 978-3-540-74252-4. ↑ Chris Vuille; Serway, Raymond A.; Faughn, Jerry S. (2009). College physics. Belmont, CA: Brooks/Cole, Cengage Learning. p. 355. ISBN 0-495-38693-6. http://books.google.ca/books?id=CX0u0mIOZ44C&pg=PT355. ↑ Balescu, R. (1975). Equilibrium and Nonequilibrium Statistical Mechanics, Wiley, New York, ISBN 0- 471-04600-0. ↑ De Groot, S.R., Mazur, P. (1962). Non-equilibrium Thermodynamics, North Holland, Amsterdam. ↑ Glansdorff, P., Prigogine, I. (1971). Thermodynamic Theory of Structure, Stability and Fluctuations, Wiley-Interscience, London, ISBN 0-471-30280-5.
  • 90.
    ↑ Šilhavý, M.(1997). The Mechanics and Thermodynamics of Continuous Media, Springer, Berlin, ISBN 3-540-58378-5, page 137. ↑ Ben-Naim, A. (2008). A Farewell to Entropy: Statistical Thermodynamics Based on Information, World Scientific, New Jersey, ISBN 978-981-270-706-2. Further reading Atkins, Peter, 2007. Four Laws That Drive the Universe. OUP Oxford. Goldstein, Martin, and Inge F., 1993. The Refrigerator and the Universe. Harvard Univ. Press. A gentle introduction.ar:‫ال حراري ة ال دي نام ي كا ق وان ين‬ ca:Lleis de la termodinàmica cs:Termodynamický zákon de:Thermodynamik#Kurze Zusammenfassung der Hauptsätze fa:‫ ت رمودي نام يک ق وان ين‬fr:Principes de la thermodynamique gl:Leis da termodinámica ko:열역학 법칙 id:Hukum termodinamika lt:Termodinamikos dėsniai ml: ms:Hukum termodinamik nl:Hoofdwetten van de thermodynamica ro:Principiile termodinamicii ru:Начала термодинамики sl:Zakoni termodinamike fi:Termodynamiikan pääsäännöt sv:Termodynamikens huvudsatser th: tr:Termodinamik kanunları uk:Закони термодинаміки Retrieved from "http://mediawikifr.dp.teoma.com/wiki/Laws_of_thermodynamics" Category: Laws of thermodynamics The content on this page originates from Wikipedia and is licensed under the GNU Free Document License or the Creative Commons CC-BY-SA license. Related Web Search Thermodynamic Laws Expand Your Search Entropy Heat Transfer Laws of Physics
  • 91.
    Related Q&A Q What isthe First Law of Thermodynamics? The first law of thermodynamics is that energy can be transformed but not destroyed or created. This is also known as energy conservation. It could be argued that humans are energy...Read more » Source:answers.ask.com Q What is the Third Law of Thermodynamics? The third law of thermodynamics basically states that it is impossible to cool an object all the way down to absolute zero. The theory is based on the entropy of perfect crystals.Read more » Source:answers.ask.com Q What are the Laws of Thermodynamics? The laws of thermodynamics describe the movement of heat and work in the thermodynamic process. They have become some of the most important in all of physics. Look here for more in...Read more » Source:answers.ask.com Related Images
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    Proteins Sequence Analysis Taxonomy Training &Tutorials Variation About NCBI Accesskeys My NCBISign in to NCBISign Out PMC US National Library of Medicine National Institutes of Health Top of Form Search term Search database PMC Search Limits Advanced Journal list Help Bottom of Form Journal List > Appl Microbiol > v.11(6); Nov 1963 >
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    PMC1058043 Appl Microbiol. 1963November; 11(6): 523–528. PMCID: PMC1058043 Microbiological Production of Gibberellic Acid in Glucose Media1 A. Sanchez-Marroquin Escuela Nacional de Ciencias Quimícas, Universidad de México, Mexico, D.F., Mexico 1This paper was presented at the II Latin-American Congress of Microbiology, San José, Costa Rica, 10- 16 December 1961. Author information ► Copyright and License information ► Copyright notice Abstract Gibberellic acid production from various substrates was studied in 43 strains of Fusarium, among which F. moniliforme strain IOC-3326 was selected as the best producer. Experiments were carried out in shaker flasks and pilot plant fermentors. The results indicate that the best substrate for gibberellic acid production with this strain is composed of the following: glucose, 20 g; corn steep liquor, 25 g; ammonium nitrate, 2.6 g; monopotassium phosphate, 0.5 g; potassium sulfate, 0.2 g; and water, 1000 ml. Glucose, ammonium nitrate, and corn steep liquor were found to be critical. With this medium, maximal yields of 1196 mg per liter in shaker flasks and 997 mg per liter in fermentors were produced. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (923K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.
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    528 Selected References These referencesare in PubMed. This may not be the complete list of references from this article. Bird HL, Pugh CT. A Paper Chromatographic Separation of Gibberellic Acid and Gibberellin A. Plant Physiol. 1958 Jan;33(1):45–46. [PMC free article] [PubMed] DARKEN MA, JENSEN AL, SHU P. Production of gibberellic acid by fermentation. Appl Microbiol. 1959 Sep;7:301–303. [PMC free article] [PubMed] STODOLA FH, RAPER KB, FENNELL DI, CONWAY HF, SOHNS VE, LANGFORD CT, JACKSON RW. The microbiological production of gibberellins A and X. Arch Biochem Biophys. 1955 Jan;54(1):240–245. [PubMed] Articles from Applied Microbiology are provided here courtesy of American Society for Microbiology (ASM) Formats: Summary | Page Browse | PDF (923K) Related citations in PubMed Gibberellic acid production by Fusarium moniliforme on lupin seed extract. [Acta Microbiol Pol. 1994] Gibberellic acid production by Fusarium moniliforme on lupin seed extract. Gulewicz K, Rataj-Guranowska M, Lukaszewska N, Michalski Z. Acta Microbiol Pol. 1994; 43(1):73-7. Survey of some Fusarium moniliforme strains from different host plants for compounds possessing gibberellin-like activity. [Zentralbl Bakteriol Parasitenkd Infektionsk...]
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    Survey of someFusarium moniliforme strains from different host plants for compounds possessing gibberellin-like activity. El-Bahrawi S. Zentralbl Bakteriol Parasitenkd Infektionskr Hyg. 1977; 132(2):178-83. Biosynthesis of gibberellic acid from milk permeate in repeated batch operation by a mutant Fusarium moniliforme cells immobilized on loofa sponge. [Bioresour Technol. 2009] Biosynthesis of gibberellic acid from milk permeate in repeated batch operation by a mutant Fusarium moniliforme cells immobilized on loofa sponge. Meleigy SA, Khalaf MA. Bioresour Technol. 2009 Jan; 100(1):374-9. Epub 2008 Aug 5. Morphological mutants of Gibberella fujikuroi for enhanced production of gibberellic acid. [J Appl Microbiol. 2006] Morphological mutants of Gibberella fujikuroi for enhanced production of gibberellic acid. Lale G, Jogdand VV, Gadre RV. J Appl Microbiol. 2006; 100(1):65-72. EFFECTS OF CORN STEEP LIQUOR AND THIAMINE ON L-GLUTAMIC ACID FERMENTATION OF HYDROCARBONS.IV. UTILIZATION OF HYDROCARBONS BY MICROORGANISMS. [Appl Microbiol. 1965] EFFECTS OF CORN STEEP LIQUOR AND THIAMINE ON L-GLUTAMIC ACID FERMENTATION OF HYDROCARBONS.IV. UTILIZATION OF HYDROCARBONS BY MICROORGANISMS. TAKAHASHI J, KOBAYASHI K, IMADA Y, YAMADA K. Appl Microbiol. 1965 Jan; 13:1-4. See reviews... See all... Links PubMed PubMed PubMed citation for this article Substance Substance PubChem Substance links Taxonomy Taxonomy Related taxonomy entry
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    f42da7e2-09e3-4200-8fda-9d0df24fc5ad Y2:f42da7e2-09e3-4200-8fda-9d0df24fc5adSkip to content Librarians Authors & Editors Societies Register Sign in Mobile Browse Products Redeem a voucher Shortlist Cart The online platform for Taylor & Francis Group content Search Search Advanced Search Within current journal Entire site Home > List of Issues > Table of Contents > Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source Browse journal View all volumes and issues Current issue
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    Latest articles Most readarticles Most cited articles Authors and submissions Call for papers Instructions for authors Submit online Subscribe Journal information About this journal Aims & scope Editorial board Abstracting & indexing Related websites News & offers Environmental Technology Volume 18, Issue 5, 1997
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    Evaluation of SomeFood Industry Wastes for Production of Gibberellic Acid by Fungal Source Preview Access options DOI: 10.1080/09593331808616569 N. Cihangir & N. Aksöza pages 533-537 Publishing models and article dates explained Version of record first published: 11 May 2010 Article Views: 13 Alert me TOC email alert TOC RSS feed Citation email alert Citation RSS feed Abstract The control of environmental pollution and the recovery of agricultural, industrial and municipal wastes by converting them into useful products are two relevant biotechnological goals. In this study, the possibility of utilising food industry waste and residues as sources of carbon for gibberellic acid production by Aspergillus niger was investigated. Media prepared from molasses, vinasse, whey, sugar-beet waste and fruit pomace were used and GA3 yields were found in concentrations 155, 136.57, 120, 73, 118.13 mg l−1 respectively in such media. It was observed that food industry wastes can be used and evaluated as cheap sources of carbon for gibberellic acid production. Download full text Keywords food industry wastes, evaluation, production,
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    gibberellic acid Related Add to shortlist Link Permalink http://dx.doi.org/10.1080/09593331808616569 Download Citation Recommend to: A friend First page preview Close Download full text Click to increase image sizeClick to decrease image size Information Citations Reprints & permissions Details Citation information: Web of Science ® Version of record first published: 11 May 2010 Journal news 2011 Impact Factor: 1.406 ©2012 Thomson Reuters, 2011 Journal Citation Report® New journal - Environmental Technology Reviews for 2012!
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    Products Redeem a voucher Shortlist Cart The online platform for Taylor & Francis Group content Search Search Advanced Search Within current journal Entire site Home > List of Issues > Table of Contents > Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source Browse journal View all volumes and issues Current issue Latest articles Most read articles Most cited articles Authors and submissions Call for papers Instructions for authors Submit online Subscribe Journal information About this journal
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    Aims & scope Editorialboard Abstracting & indexing Related websites News & offers Environmental Technology Volume 18, Issue 5, 1997 Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source Preview Access options DOI: 10.1080/09593331808616569 N. Cihangir & N. Aksöza pages 533-537 Publishing models and article dates explained Version of record first published: 11 May 2010 Article Views: 13
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    Alert me TOC email alert TOC RSS feed Citation email alert Citation RSS feed Abstract The control of environmental pollution and the recovery of agricultural, industrial and municipal wastes by converting them into useful products are two relevant biotechnological goals. In this study, the possibility of utilising food industry waste and residues as sources of carbon for gibberellic acid production by Aspergillus niger was investigated. Media prepared from molasses, vinasse, whey, sugar-beet waste and fruit pomace were used and GA3 yields were found in concentrations 155, 136.57, 120, 73, 118.13 mg l−1 respectively in such media. It was observed that food industry wastes can be used and evaluated as cheap sources of carbon for gibberellic acid production. Download full text Keywords food industry wastes, evaluation, production, gibberellic acid Related Add to shortlist Link Permalink http://dx.doi.org/10.1080/09593331808616569 Download Citation Recommend to: A friend First page preview Close Download full text
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    Click to increaseimage sizeClick to decrease image size Information Citations Reprints & permissions Details Citation information: Web of Science ® Version of record first published: 11 May 2010 Journal news 2011 Impact Factor: 1.406 ©2012 Thomson Reuters, 2011 Journal Citation Report® New journal - Environmental Technology Reviews for 2012! Librarians Librarians' area Pricing
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    Skip to content Librarians Authors & Editors Societies Register Sign in Mobile Browse Products Redeem a voucher Shortlist Cart The online platform for Taylor & Francis Group content Search Search Advanced Search Within current journal Entire site Home > List of Issues > Table of Contents > Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source Browse journal View all volumes and issues Current issue Latest articles Most read articles
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    Most cited articles Authorsand submissions Call for papers Instructions for authors Submit online Subscribe Journal information About this journal Aims & scope Editorial board Abstracting & indexing Related websites News & offers Environmental Technology Volume 18, Issue 5, 1997 Evaluation of Some Food Industry Wastes for Production of Gibberellic Acid by Fungal Source Preview Access options
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    DOI: 10.1080/09593331808616569 N. Cihangir & N. Aksöza pages 533-537 Publishing models and article dates explained Version of record first published: 11 May 2010 Article Views: 13 Alert me TOC email alert TOC RSS feed Citation email alert Citation RSS feed Abstract The control of environmental pollution and the recovery of agricultural, industrial and municipal wastes by converting them into useful products are two relevant biotechnological goals. In this study, the possibility of utilising food industry waste and residues as sources of carbon for gibberellic acid production by Aspergillus niger was investigated. Media prepared from molasses, vinasse, whey, sugar-beet waste and fruit pomace were used and GA3 yields were found in concentrations 155, 136.57, 120, 73, 118.13 mg l−1 respectively in such media. It was observed that food industry wastes can be used and evaluated as cheap sources of carbon for gibberellic acid production. Download full text Keywords food industry wastes, evaluation, production, gibberellic acid Related Add to shortlist
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    Link Permalink http://dx.doi.org/10.1080/09593331808616569 Download Citation Recommend to: A friend First page preview Close Download full text Click to increase image sizeClick to decrease image size Information Citations Reprints & permissions Details Citation information: Web of Science ® Version of record first published: 11 May 2010 Journal news 2011 Impact Factor: 1.406 ©2012 Thomson Reuters, 2011 Journal Citation Report® New journal - Environmental Technology Reviews for 2012!
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    Help FAQs Contact us Feedback form Press releases Taylor & Francis Group Privacy Policy & Cookies Terms & Conditions Accessibility Feedback Powered by Atypon® Literatum Gibberellic acid From Wikipedia, the free encyclopedia Jump to: navigation, search This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2012) Gibberellic acid
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    IUPAC name[show] Identifiers CAS number 77-06-5 PubChem 522636 ChemSpider 7995349 UNII BU0A7MWB6L EC number 201-001-0 KEGG C01699 ChEBI CHEBI:28833 ChEMBL CHEMBL566653 Jmol-3D images Image 1 SMILES [show] InChI [show] Properties Molecular formula C19H22O6
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    Molar mass 346.37 g/mol Melting point 233 - 235 °C (decomposition) Solubility in water 5 g/l (20 °C) Hazards EU classification Irritant (Xi) R-phrases R36 S-phrases R26, S36 (verify) (what is: / ?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references Gibberellic acid (also called Gibberellin A3, GA, and GA3) is a hormone found in plants. Its chemical formula is C19H22O6. When purified, it is a white to pale-yellow solid. Gibberellic acid is a simple gibberellin, a pentacyclic diterpene acid promoting growth and elongation of cells. It affects decomposition of plants and helps plants grow if used in small amounts, but eventually plants develop tolerance to it[citation needed]. GA stimulates the cells of germinating seeds to produce mRNA molecules that code for hydrolytic enzymes. Gibberellic acid is a very potent hormone whose natural occurrence in plants controls their development. Since GA regulates growth, applications of very low concentrations can have a profound effect while too much will have the opposite effect.[1] It is usually used in concentrations between 0.01 and 10 mg/L. GA was first identified in Japan in 1935, as a metabolic byproduct of the plant pathogen Gibberella fujikuroi (thus the name), which afflicts rice plants; fujikuroi-infected plants develop bakanae ("foolish seedling"), which causes them to grow so much taller than normal that they die from no longer being sturdy enough to support their own weight. Gibberellins have a number of effects on plant development. They can stimulate rapid stem and root growth, induce mitotic division in the leaves of some plants, and increase seed germination rate.
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    Gibberellic acid issometimes used in laboratory and greenhouse settings to trigger germination in seeds that would otherwise remain dormant.[1] It is also widely used in the grape-growing industry as a hormone to induce the production of larger bundles and bigger grapes, especially Thompson seedless grapes. In the Okanagan and Creston valleys, it is also used as a growth replicator in the cherry industry. [edit] See also Gibberellin Plant hormone 6-Benzylaminopurine [edit] References 1. ^ a b Riley, John M.. "Gibberellic Acid for Fruit Set and Seed Germination". http://www.crfg.org/tidbits/gibberellic.html. Retrieved 26 Oct 2012. [edit] External links No longer maintained. Safety MSDS data Synonyms at webbook.nist.gov www.crfg.org Retrieved from "http://en.wikipedia.org/w/index.php?title=Gibberellic_acid&oldid=535424207" View page ratings Rate this page What's this? Trustworthy Objective Complete Well-written I am highly knowledgeable about this topic (optional)
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