Applied Chemistry.pptx

Applied Chemistry
Course outline:
Physical Chemistry: Properties of various groups and periods of periodic table.
Atomic Structure and Interatomic bonding: Atomic structure, atomic bonding
and mechanical bonding. Polymorphism and allotropic forms. Crystallography
basics.
Basic Mechanical properties: Structure of metals and ceramics.
Thermo-chemistry: Chemical Thermodynamics, Hess’s Law, heat of Formation
and reaction, relation between H and U, measurement of heat reaction, Bomb
calorimeter
Electrochemistry: Laws of electrolysis
Industrial Chemistry: Industrial chemistry introduction, manufacturing and uses
of various hydrocarbons. Lubricants and oils. Production and application of
paints, vulcanized rubber and fuels. Environmental pollution and control.
Water Treatment Methods: Water softening, treatment of water for industrial
purposes.

Applied Chemistry
Assessment: Mid Term, Presentation, Assignments, Quizzes, Report
Writing, Final Term
Text and Reference books:
W. H. Brown and L. S. Brown, Chemistry for Engineering Students, Cengage
Learning, 3rd ed.
O. V. Roussak, H. D. Gesser, Applied Chemistry: A Textbook for Engineers
and Technologists: Springer.
S. S. Zumdahl, Chemistry: An Atoms First Approach, Cengage.
N. J. Tro, Chemistry: A Molecular Approach, Pearson.
M. J. Shultz, Engineering Chemistry, Cengage.
Bahl, B. S. Bahl, G. D. Tuli, Essential of Physical Chemistry, S. Chand
Publishing, India.

Applied Chemistry
Definition:
Applied Chemistry is the scientific field for understanding basic chemical
properties of materials and for producing new materials with well-controlled
functions. It has four areas of study: physical chemistry, materials chemistry,
chemical engineering, and environmental chemistry
Examples of applied chemistry include creation of the variety of laundry
detergents on the market and development of oil refineries
Physical Chemistry: is the study of macroscopic, and particulate phenomena in
chemical systems in terms of the principles, practices, and concepts of physics
such as motion, energy, force, time, thermodynamics, quantum chemistry,
statistical mechanics, analytical dynamics and chemical equilibrium.
Materials Chemistry: is the section of Materials Science and Engineering that
investigates the chemical nature of materials. ... The diverse nature of materials
arises from their atomic composition and their complex molecular structures,
which are organized over many different length scales.

Applied Chemistry
Chemical engineering: is a certain type of engineering which deals with the
study of operation and design of chemical plants as well as methods of
improving production. Chemical engineers develop economical commercial
processes to convert raw material into useful products.
Environmental chemistry : is the study of chemical processes that occur in
water, air, terrestrial and living environments, and the effects of human
activity on them. It includes topics such as astrochemistry, atmospheric
chemistry, environmental modelling, geochemistry, marine chemistry and
pollution remediation.

Atomic Structure and Interatomic bonding:
Fundamental Concepts of the Atom
Our current model of the structure of atoms has been accepted for nearly a century,
but it took great creativity and many ingenious experiments to develop. The atom is
composed of a small, compact core called the nucleus surrounded by a disperse cloud
of electrons. The nucleus is composed of two types of particles: protons and neutrons.
There is so much space between the electrons and the nucleus that it is impossible
to show it to scale in an illustration. Consider the figure which show the relative
positions of the protons, neutrons, and electrons. But if the protons and neutrons were
actually the size shown, then the electrons would be hundreds
of meters away. Another misunderstanding promoted by this type of illustration
is the picture of electrons following regular orbits around the nucleus. A better model
of atomic structure views the electrons as clouds of negative charge that surround the
nucleus, as opposed to particles that orbit around it in an orderly way (Figure (b)).

Now we turn our attention to the numbers of protons, neutrons, and electrons in
the atom. Electric charge provides an important constraint on these numbers. Protons
are positively charged, electrons are negatively charged, and neutrons are neutral.
Atoms
themselves are also electrically neutral, so the numbers of protons and electrons
present must be such that their charges will cancel each other. You may know from
physics that the SI unit of charge is the coulomb (C). Experiments have shown that
the electrical charges on a proton and an electron are equal and opposite. Every
electron
carries a charge of −1.602 × 10−19 C, whereas every proton carries a charge of
+1.602 × 10−19 C. So for an atom to remain neutral, the numbers of electrons and
protons must be equal. Because neutrons have no charge, the number of neutrons
present is not restricted by the requirement for electrical neutrality. For most elements,
the number of neutrons can vary from one atom to another, as we’ll see.

Atomic Number and Mass Number
The number of protons in a particular atom, referred to as the atomic number, identifi
es the element. The atomic number of carbon is six, which tells us that a neutral
carbon atom has six protons. Electrical neutrality requires that a carbon atom also must
have six electrons. The great majority of carbon atoms—roughly 99%—also contain
six neutrons. But some carbon atoms contain seven or even eight neutrons. Atoms of
the same element that have different numbers of neutrons are called isotopes. Protons
and electrons govern nearly all of the important chemical properties of atoms, so generally
isotopes cannot be separated chemically. But the existence and even the relative
abundance of isotopes can be proven by careful examinations of the mass of atoms.
Protons and neutrons have similar masses; each is nearly 2000 times more massive
than the electron. So the mass of any atom is concentrated in its nucleus. Individual
atoms are so small and light that reporting their masses in conventional units
such as kilograms or grams is not convenient.

Atomic Number and Mass Number
Instead we use a unit that is appropriate to the atomic scale: the atomic mass unit or
amu.
1 amu = 1.6605 × 10−24 g
Both the neutron and the proton have masses very close to one amu. The mass of a
neutron is 1.009 amu, and that of a proton is 1.007 amu. The mass of an electron,
in contrast, is just 0.00055 amu. So for many practical purposes, we can determine
the mass of an atom simply by counting the number of protons and neutrons. That
number will be the mass in amu, to a fairly reasonable approximation. Because of this,
the combined total of protons and neutrons is called the mass number of the atom.
Because isotopes are atoms of the same element with different numbers of neutrons,
they will have the same atomic number but different mass numbers.

Isotope: are two or more types of atoms that have the same atomic number (number
of protons in their nuclei) and that differ in nucleon numbers (mass numbers) due to
different numbers of neutrons in their nuclei. While all isotopes of a given element have
almost the same chemical properties, they have different atomic masses and physical
properties. The term isotope is formed from the Greek roots isos ("equal") and topos
("place"), meaning "the same place"; thus, the meaning behind the name is that
different isotopes of a single element occupy the same position on the periodic table.
The number of protons within the atom's nucleus is called atomic number and is equal
to the number of electrons in the neutral (non-ionized) atom. Each atomic number
identifies a specific element, but not the isotope; an atom of a given element may have
a wide range in its number of neutrons. The number of nucleons (both protons and
neutrons) in the nucleus is the atom's mass number, and each isotope of a given
element has a different mass number.
For example, carbon-12, carbon-13, and carbon-14 are three isotopes of the
element carbon with mass numbers 12, 13, and 14, respectively. The atomic number of
carbon is 6, which means that every carbon atom has 6 protons so that the neutron
numbers of these isotopes are 6, 7, and 8 respectively.

Atomic Symbols
All the information about the structure of the atom, which we have just discussed, can
be written in scientific shorthand, using atomic symbols. The general atomic symbol
can be written as 𝑍
𝐴
𝐸
Here E represents the atomic symbol for the element in question, the superscript
A is the mass number, and the subscript Z is the atomic number. The symbol for
carbon-12, for example, is 6
12
𝐶.
Many atomic symbols are fairly obviously derived from the name of the element,
such as the use of C for carbon in our example. For other elements, the symbol is
based on the Latin name. The symbol for iron, for example, is Fe, derived from the
Latin name ferrum. An atom of iron with 26 protons and 30 neutrons is represented
as 26
56
𝐹𝑒.
A full list of elements and their symbols can be found in periodic Table.

Atomic Masses
The atomic mass is defined as the average mass of an atom of a particular element.Carbon
has two stable isotopes with masses of 12.0000 and 13.0036 amu, respectively. So why is
the average mass 12.011 and not something closer to 12.5? The answer is that when we
take the average mass, we must account for the relative abundance of each isotope.
Suppose that we could measure the mass of a 100-atom sample. Based on the isotopic
abundances, we would expect to have 99 atoms of carbon-12 and only a single atom of
carbon-13. In any sample that we can actually weigh, the number of atoms will be far
greater than 100. Even using the best available laboratory balances, the smallest quantity of
matter that can be weighed is about a nanogram, or 10−9 g. A nanogram of carbon would
contain more than 1013 atoms. For such large numbers of atoms, it is safe to assume that
the fraction of each isotope present will be determined by the natural abundances. For
carbon, the fact that we only need to consider two stable isotopes makes the calculation
fairly simple. We can multiply the mass by the fractional abundance to weight each isotope’s
contribution to the atomic mass.
Carbon-12: 12.0000 × 0.9893 = 11.87, Carbon-13: 13.0036 × 0.0107 = 0.139
Weighted average mass = 11.87 + 0.139 = 12.01 , The value of 12.011 found in the periodic

Atomic Masses
EXAMPLE PROBLEM 2.1 (Polyvinyl chloride)
The chlorine present in PVC has two stable isotopes. 35Cl with a mass of 34.97 amu
makes up 75.77% of the natural chlorine found. The other isotope is 37Cl, whose mass
is 36.95 amu. What is the atomic mass of chlorine?
Strategy To determine the atomic mass, we must calculate the average mass
weighted by the fractional abundance of each chlorine isotope. Because there are only
two stable isotopes, their abundances must add up to 100%. So we can calculate the
abundance of 37Cl from the given abundance of 35Cl.
Solution First, we calculate the abundance of the chlorine-37 isotope:
Abundance of 37Cl = 100% − 75.77% = 24.23%
Now we can calculate the contribution of each isotope to the atomic mass.
35Cl: 34.97 × 0.7577 = 26.50, 37Cl: 36.95 × 0.2423 = 8.953
Weighted average mass = 26.50 + 8.953 = 35.45, So the atomic mass of chlorine is 35.45 amu.

Ions:
Ions
Any atom or group of atoms that bears one or more positive or negative electrical charges is
called Ion. Positively charged ions are called cations
The charge of the electron is considered negative by convention. The negative charge of an
electron is equal and opposite to charged proton(s) considered positive by convention. The
net charge of an ion is not zero due to its total number of electrons being unequal to its total
number of protons.
Ions can also play important roles in many chemical processes, including several that are
important in the large-scale production of polymers. When an ion is derived from a single
atom it is called a monatomic ion. When groups of atoms carry a charge they are called
polyatomic ions. Monatomic or polyatomic ions may carry either negative or positive
charges. Negatively charged ions are called anions, and they contain more electrons than
protons. Similarly, an ion with more protons than electrons has a positive charge and is
called a cation.
Two fundamental aspect about electric charge are:
First, opposite charges attract each other and like charges repel one another. And second,
electric charge is conserved. These two ideas have important implications for the formation
of ions in chemical processes.

Ions:
Ions-Mathematical Description
The statement that “opposites attract and likes repel” can be quantified mathematically.
Coulomb’s law, describes the interaction of charged particles. The attraction of opposite charges
and the repulsion of like charges are both described mathematically by one simple equation:
Here q1 and q2 are the charges, is a constant called the permittivity of a vacuum, and r is the
distance between the charges. F is the force the objects exert on one another as a result of their
charges. When both charges have the same sign—either positive or negative—the resultant
value for the force is a positive number. When the charges are opposite, the value is negative.
This is consistent with the usual sign conventions used for force and energy; a negative value of F
indicates an attractive force and a positive value a repulsive one. Now consider the effect of
varying the distance, r, between two ions. If two positively charged particles are initially very far
apart (effectively infinite distance), the r2 term in the denominator of Equation will be very large.
This in turn means that the force F will be very small, and so the particles will not interact with
each other significantly. As the two like charges are brought closer together, the r2 term in the
denominator shrinks and so the (positive) force grows larger: the particles repel each other. If we
somehow force the particles closer together, the repulsive force will continue to grow.

Ions:
Ions and Their Properties : Many monatomic cations and anions exist. These ions can exist in the
gas phase, and many are important in atmospheric chemistry. But we encounter ions most
frequently when dealing with the chemistry of substances dissolved in water. For example,
sodium atoms lose an electron relatively easily to form the sodium cation, Na+. Because it still
has 11 protons, this ion retains the symbol of sodium, yet it does not behave at all like an atom of
sodium. Consider an order of French fries. You may have heard news stories about the high
amount of sodium in an order of fries, and concerns have been raised about the possible health
effects of too much sodium in our diets. This statement could be confusing because here the
word “sodium” does not refer to sodium metal. In fact, if we place sodium metal on freshly made
French fries, the metal will burst into flame! The sodium we hear about in stories on diet and
health is actually sodium ion, which is added to the fries when salt is sprinkled on. Too much salt
might still be a health concern, but we certainly don’t worry about the salt igniting. There is a big
difference between ions and atoms, at least in this case. In contrast to sodium, chlorine readily
gains an extra electron forming the chloride ion Cl−. Again, there is a noticeable difference
between the ion and the atom of chlorine. The table salt we discussed above is sodium chloride,
which contains chloride anions. Just like sodium, these chloride ions are present in French fries
or any other salted foods. Chlorine atoms, on the other hand, combine in pairs to form a
yellowish-green gas, Cl2, which irritates the lungs and can be toxic. The behavior of the ion is
clearly much different from that of the neutral atom or molecule.

Compounds and Chemical Bonds:
Chemical Formulas:
A chemical compound is a pure substance made up of atoms of two or more elements joined
together by chemical bonds. In any compound, the atoms combine in fixed whole number ratios.
In any such combination, the resultant substance behaves differently from the atoms alone. In
many compounds, atoms combine to form discrete particles called molecules. Molecules can be
broken down into their constituent atoms, but the resulting collection of atoms no longer
behaves like the original molecule. Other materials are composed of vast arrays or extended
structures of atoms or ions but do not form discrete molecules. Alloys, metals, and ionic solids
(composed of paired ions) fall into this category of chemical compounds. We’ve seen how we can
use atomic symbols as shorthand notation to designate atoms. That same idea can be extended
to describe the composition of either molecules or extended compounds in a simple symbolic
representation.
A chemical formula describes a compound in terms of its constituent elements. We will actually
encounter two distinct types of chemical formulas: molecular formulas and empirical formulas.
The molecular formula of a compound is a kind of parts list that describes the atomic
composition of a molecule efficiently. The molecular formula of the ethylene (colorless
flammable gas) monomer from which polyethylene is produced is C2H4; this tells us that there
are two carbon atoms and four hydrogen atoms per molecule.
The empirical formula tells us only the relative ratio between the numbers of atoms of the

different elements present. Let’s consider ethylene again. The ratio of carbon atoms to
hydrogen is 1:2. So the empirical formula is CH2. When dealing with an empirical formula, it is
important to realize that it does not tell how large or small an individual molecule of the
compound might be; only the relative numbers of atoms of each element are given. We often
emphasize this fact by writing a subscript ‘n’ on the entire formula. For ethylene, this would
give us (CH2)n, which means that each molecule must contain some integral number of CH2
units.
There are four rules that allow us to write most formulas:
1. Indicate the types of atoms in the substance by their atomic symbols.
2. The number of each atom in the compound is indicated by a subscript to the right
of the atomic symbol. For example, the chemical formula of ethylene, C2H4, tells
us that each molecule contains two carbon atoms and four hydrogen atoms.
3. Groups of atoms can be designated by using parentheses. Subscripts outside
these parentheses mean that all atoms enclosed in the parentheses are multiplied
by the value indicated in the subscript.
4. Water molecules associated with certain compounds called hydrates are indicated
separately from the rest of the compound.

Chemical Bonding
Atoms combine to make compounds by forming chemical bonds. Several different types of
chemical bonds are possible, and once we learn to recognize them, these types of bonds will
help us to understand some of the chemical properties of many substances.
All chemical bonds share two characteristics. First, all bonds involve exchange or sharing of
electrons. Second, this exchange or sharing of electrons results in lower energy for the
compound relative to the separate atoms. A chemical bond will not form, or will have only a
temporiry existence, unless it lowers the overall energy of the collection of atoms involved.
Chemical bonds can be divided into three broad categories: ionic, covalent, and metallic.
Some compounds are composed of collections of oppositely charged ions that form an
extended array called a lattice. The bonding in these compounds is called ionic bonding. To
form the ions that make up the compound, one substance loses an electron to become a
cation, while another gains an electron to become an anion. We can view this as the transfer
of an electron from one species to another. ionic compound, NaCl.
Ionic compounds form extended systems or lattices of alternating positive and negative
charges. Although the formula NaCl correctly indicates that sodium and chlorine are present
in a 1:1 ratio, we cannot really identify an individual “molecule” of NaCl. To emphasize this

Chemical Bonding
distinction, we sometimes refer to a formula unit, rather than a molecule, when talking
about ionic compounds. The formula unit is the smallest whole number ratio of atoms in an
ionic compound.

Chemical Bonding
Metals represent another type of extended system, but here the chemical bonding is totally
different. In metals, the atoms are once again arranged in a lattice, but positively and
negatively charged species do not alternate. Instead, the nuclei and some fraction of their
electrons comprise a positively charged “core” localized at these lattice points, and other
electrons move more or less freely throughout the whole array. This is called metallic
bonding. Metallic bonding leads to electrical conductivity because electrons can move easily
through the bulk material. Figure shows a schematic illustration of the concept of metallic
bonding.

Chemical Bonding
When electrons are shared between pairs of atoms rather than donated from one atom to
another or mobile across an entire lattice, we have covalent bonds. In covalent bonds,
electrons are usually shared in pairs. Two electrons (and sometimes four or six) are located
between two nuclei and the sharing leads to an attraction between the nuclei. The long
chains in all polymers are formed by covalent bonds in which electrons are shared between
adjacent carbon atoms.

The Periodic Table :
One of the most recognizable tools of chemistry is the periodic table. Periodic table
summarizes a wealth of information about the behavior of elements, organizing them
simultaneously in ascending order of atomic number and in groups according to chemical
behavior. An experienced chemist can get a rough idea of an element’s properties simply
from where that element sits in the periodic table.
Russian scientist Mendeleev had published his first periodic table and enumerated the
periodic law: when properly arranged, the elements display a regular and periodic variation
in their chemical properties. The most significant and impressive feature of Mendeleev’s
work was his prediction of the existence of undiscovered elements. He left holes in his
proposed table at positions where no known element seemed to fi t. Later, when the
elements to fill in these holes were identified, the scientific community accepted
Mendeleev’s work. The discovery of the periodic law and construction of the periodic table
represents one of the most significant creative insights in the history of chemistry. Prior to
Mendeleev’s time, chemists had to learn the properties of each element individually. As more
and more elements were discovered, that task became increasingly difficult. The periodic
table helped the study of chemistry to expand quickly by providing a simple, visual means to
organize the elements in terms of their chemical and physical properties.

Periods and Groups
The modern periodic table simultaneously arranges elements in two important ways:
the horizontal rows of the table, called periods, and the vertical columns, called groups. The
term “period” is used for the rows because many important properties of the elements vary
systematically as we move across a row. Figure shows a plot of the density of elements, all in
their solid state, as a function of atomic number. From the graph, it is clear that density varies
according to a fairly regular pattern that goes through a series of minima and maxima.
Different colors are used for the data points in this graph to show how the variation in density
is correlated with position in the periodic table. Each color represents a period (row) in the
table. Because the elements in the periodic table are arranged in order of increasing atomic
number, moving across each segment of the graph corresponds to moving from left to right
across the corresponding row of the periodic table. You can see readily that as we move
across a row in this way, the density of the elements is initially small, increases until passing
through a maximum, and then decreases again. 2nd figure shows the same data, with the
density represented by the shading of each element’s box. This representation clearly shows
how the density of the elements varies regularly across each row of the table. The rows in the
table are numbered 1 through 7 sequentially from top to bottom.

Periods and Groups

Periods and Groups
Although the properties of the elements can vary widely across a period, each column
collects elements that have similar chemical properties. Most elements can combine with
hydrogen to form compounds. The graph in Figure shows the number of hydrogen atoms with
which an atom of each element will combine, and the regular variation in the plot clearly
shows that this is a periodic property. Elements in a group (column) combine with the same
number of hydrogen atoms. Fluorine, chlorine, and bromine each combine with one atom of
hydrogen, for example, and all fall in the same group.
These types of chemical similarities were among the evidence that led to the development of
the periodic table, so some of the groups predate the general acceptance of the table. These
groups of elements were assigned names and those names have remained with them. Thus
the elements in the far left-hand column (Li, Na, K, Rb, and Cs) are known collectively as alkali
metals. Similarly, Be, Mg, Ca, Sr, and Ba are called alkaline earths, and F, Cl, Br, and I are
referred to as halogens. He, Ne, Ar, Kr, and Xe were discovered much later than most of the
other elements, and they have been named rare gases or noble gases. Other groups are
named, but their names are less commonly used and won’t be mentioned here.

Periods and Groups
There are also names for different regions of the table. Elements in the two groups on the left
side of the table and the six groups on the right side are collectively referred to as
representative elements, or main group elements. Elements that separate these two parts
of the representative groups in the main body of the periodic table are called transition
metals. Iron is an example of a transition metal. The elements that appear below the rest of
the periodic table are called lanthanides (named after the element lanthanum, Z = 57) and
actinides (named after the element actinium, Z = 89). In addition to these names, several
numbering systems have been used to designate groups. Current convention dictates
numbering from left to right starting with 1 and proceeding to 18. Thus, for example, the
group containing C, Si, Ge, Sn, and Pb is referred to as Group 14.

Metals, Nonmetals, and Metalloids
Another way to classify an element is as a metal, nonmetal, or metalloid. Once again, the
periodic table conveniently arranges elements so that one can place a given element easily
into one of these categories.

Most of the elements are metals. Their general location in the periodic table is toward the
left and bottom, as seen in the coloring of the periodic table in Figure Metals share a number
of similarities in chemical and physical properties. Physically, metals are shiny, malleable, and
ductile (meaning they can be pulled into wires). They also conduct electricity, so wires are
always made from metals. Chemical properties can also be used to distinguish metals.
Metallic elements tend to form cations in most of their compounds.
Nonmetals occupy the upper right-hand portion of the periodic table. There are fewer
nonmetals than metals. But when we consider the relative importance of elements,
nonmetals hold their own because of their role in the chemistry of living things. Most of the
molecules that make up the human body consist predominantly or exclusively of the
nonmetallic elements carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus. As our
examples so far might lead you to guess, polymers also consist almost exclusively of
nonmetallic elements. In contrast to metals, nonmetals are not shiny, malleable, or ductile
nor are they good conductors of electricity. These physical properties provide one means by
which we can distinguish metals from nonmetals.
Whether an element is a metal or nonmetal may seem simple to determine based

on the physical properties cited above. Yet, some elements cannot be classified easily as
either metal or nonmetal. The question whether or not a substance conducts electricity, for
example, does not always have a simple yes or no answer. Lacking a reliable means of
drawing a clean boundary between the two categories, scientists have generally chosen to
refer to intermediate cases as metalloids or semimetals. In the periodic table, metalloids are
clustered along a diagonal path, as shown in Figure.

Inorganic and Organic Chemistry:
Just as engineering can be broken down into various specialties, so too, chemistry can
be viewed as a collection of subfields. Two of the most fundamental areas of chemistry
are organic chemistry and inorganic chemistry. These names arise from the fact
that at one time organic chemistry would have been defined as the chemistry of living
things. A more modern definition is that organic chemistry is the study of compounds
of the element carbon. As we’ve already seen, this includes naturally occurring biological
molecules and also nearly all synthetic polymers. Inorganic chemistry is the study of all
other elements and their compounds.
Inorganic Chemistry:
Many inorganic compounds exist as relatively small molecules whose atoms are joined
together through covalent bonds. One such compound is silicon tetrachloride, SiCl4, which
has important uses in the production of semiconductors. Four chlorine atoms surround a
central silicon atom, and each chlorine shares one pair of electrons with the silicon. Silicon
and chlorine are both main group elements, found in Groups 14 and 17 of the periodic
table, respectively. As mentioned, elements from the same group tend to display similar
chemical properties.

Inorganic Chemistry and Transition Metals:
Thus once we know that SiCl4 exists, we might expect that other pairs of elements from
the same groups might form similar compounds. And this prediction is correct: compounds
such as SnCl4 and CF4 do exist and have structures and bonds analogous to SiCl4.
Other compounds of the main group elements form extended ionic structures, such as that
of NaCl. But despite the difference in the types of chemical bonds employed, we can still
readily predict that similar compounds should exist for other pairs of elements from the
same groups. From the periodic table, we see that sodium is in Group 1 and chlorine is in
Group 17. So we can expect that other pairs of elements from these columns of the table
will form ionic solids, too. Again, our prediction is accurate; compounds such as LiCl, NaF,
and KBr have structures analogous to that of NaCl. The reason for the existence of these
similar compounds is simple. All of the metals in Group 1 form cations with a 1+ charge,
and all of the elements in Group 17 form anions with a 1− charge. Any of these cations can
combine with any of the anions in a 1:1 ratio to form neutral compounds.

The chemistry of transition metals is somewhat more complicated than that of the main
group elements, though, because most transition metals can form multiple cations with
different charges.
Iron commonly forms two different monatomic cations:
Fe2+ and Fe3+. As a result of this, iron can form a more diverse set of compounds than
Group 1 metals. It can combine with chlorine to form either FeCl2 or FeCl3, and these two
compounds have significantly different physical properties. Largely because they can form
multiple cations, the chemistry of transition metals does not vary as sharply from group to
group. Regardless of their positions in the periodic table, for example, most transition
metals can form cations with a 2+ charge. Thus predictions based simply on group number
are not as reliable here as they are for the representative elements. When considering
transition metals and their compounds, we must rely more heavily on knowledge of the
specific chemistry of each element.

The chemistry of transition metals is somewhat more complicated than that of the main
group elements, though, because most transition metals can form multiple cations with
different charges.
Iron commonly forms two different monatomic cations:
Fe2+ and Fe3+. As a result of this, iron can form a more diverse set of compounds than
Group 1 metals. It can combine with chlorine to form either FeCl2 or FeCl3, and these two
compounds have significantly different physical properties group 3 to group 12.

Organic Chemistry:
By definition, an organic compound is based on carbon atoms. So to reduce clutter in a line
drawing, the ‘C’ symbols for carbon atoms are not written. Furthermore, because organic
compounds almost always contain many hydrogen atoms, the ‘H’ symbol for any hydrogen
atom that is attached directly to a carbon atom is also not written. Symbols are written
for any elements other than carbon and hydrogen, as well as for any hydrogen atoms
that are not directly attached to carbon.
Poly(methyl methacrylate) is widely known as Plexiglas®. The structural formula for the
monomer, methyl methacrylate, is shown below. Write the corresponding line structure for
methyl methacrylate.

Chemical Nomenclature:
Although only a limited number of elements exist, the number of compounds that may be
formed from those elements is virtually boundless. Given the vast number of molecules
that can be made, we require a systematic means of assigning names to chemical
compounds. This system should be sufficiently well defined that a person who knows the
rules can draw the structure of any compound, given its systematic name. This naming
process for molecules is often referred to as chemical nomenclature.
Binary Systems
Compounds that contain only two elements are called binary compounds. Fe2O3, for
example, is a binary compound. Different rules exist for naming binary molecules held
together by covalent bonds and ionic compounds. When two nonmetals combine, they
usually form a covalent compound. But when metals and nonmetals combine with one
another, they frequently form ionic compounds.
Naming Covalent Compounds
In some cases, a given pair of elements can form compounds in a number of different
ways. Nitrogen and oxygen, for example, form NO, N2O, NO2, N2O3, N2O4, and N2O5, all
of which are stable enough to observe. So it is critical that our naming system distinguishes

these different molecules. To accomplish this, the nomenclature system uses a prefix to
specify the number of each element present. The first ten of these prefixes, which arise
from the Greek roots for the numbers, are listed in Table
In a binary compound, the element that appears first
in the formula also appears first in the name.
The first element retains its full name,
whereas the second element is described
by replacing the ending from its name with
the suffix -ide. Both elements will be preceded
by a number-designating prefix except that
when there is only one atom of the first element,
it does not carry the prefix mono-.

EXAMPLE
What are the systematic names of the following compounds? (a) N2O5, (b) PCl3, (c) P4O6?
Solution (a) N2O5: dinitrogen pentoxide, (b) PCl3: phosphorus trichloride (remember: this
is not called monophosphorus trichloride), (c) P4O6: tetraphosphorus hexoxide. (The a in
hexa- is dropped here to simplify pronunciation.)
Naming Ionic Compounds
The name of a monatomic cation is simply the name of the element followed by the
word ion. Thus, Na+ is the sodium ion, Al3+ is the aluminum ion, Ca2+ is the calcium ion, and
so forth. We have seen that some elements lose different numbers of electrons, producing
ions of different charges. Iron, for example, can form two cations, each of which, when
combined with the same anion, makes a different compound with unique physical and
chemical properties. Thus, we need a different name for each iron ion to distinguish
Fe2+ from Fe3+. The same issue arises for other ions with more than one possible charge.

There are two ways to make this distinction. In the simpler, more modern approach, called
the Stock system, an ion’s positive charge is indicated by a roman numeral in parentheses
after the element name, followed by the word ion. Thus, Fe2+ is called the iron(II) ion, while
Fe3+ is called the iron(III) ion. This system is used only for elements that form more than
one common positive ion. We do not call the Na+ ion the sodium(I) ion because (I) is
unnecessary. Sodium forms only a 1+ ion, so there is no ambiguity about the name sodium
ion.
The second system, called the common system, is not conventional but is still prevalent
and used in the health sciences. This system recognizes that many metals have two
common cations. The common system uses two suffixes (-ic and -ous) that are appended to
the stem of the element name. The -ic suffix represents the greater of the two cation
charges, and the -ous suffix represents the lower one. In many cases, the stem of the
element name comes from the Latin name of the element.
The name of a monatomic anion consists of the stem of the element name, the suffix -ide,
and then the word ion. Thus, as we have already seen, Cl− is “chlor-” + “-ide ion,” or the
chloride ion. Similarly, O2− is the oxide ion, Se2− is the selenide ion, and so forth

Element Stem Charge Modern Name Common Name
iron ferr-
2+ iron(II) ion ferrous ion
3+ iron(III) ion ferric ion
copper cupr-
1+ copper(I) ion cuprous ion
2+ copper(II) ion cupric ion
tin stann-
2+ tin(II) ion stannous ion
4+ tin(IV) ion stannic ion
lead plumb-
2+ lead(II) ion plumbous ion
4+ lead(IV) ion plumbic ion
chromium chrom-
2+ chromium(II) ion chromous ion
3+ chromium(III) ion chromic ion
gold aur-
1+ gold(I) ion aurous ion
3+ gold(III) ion auric ion
Ion Name
F−
fluoride ion
Cl−
chloride ion
Br−
bromide ion
I−
iodide ion
O2−
oxide ion
S2−
sulfide ion
P3−
phosphide ion
N3−
nitride ion

Many compounds contain polyatomic anions,. Most often, the names of these polyatomic
ions are memorized rather than being obtained by a systematic nomenclature rule. There
is, however, a system for polyatomic anions that contain oxygen and one other element,
oxyanions. The base name of the oxyanion is provided by the element that is not oxygen. If
there are two possible groupings of the element with oxygen, the one with more oxygen
atoms uses the suffix -ate and the one with fewer oxygens uses the suffix -ite. When there
are four possible oxyanions, we add a prefix per- to the -ate suffix for the most oxygens
and a prefix hypo- to the -ite suffix for the least oxygens. Chlorine is the classic example of
an element that forms four oxyanions, whose names are provided in Table
Once we know how to name both of the ions,
an ionic compound is named simply
by combining the two names. The cation
is listed fi rst in the formula unit and in
the name.

The Periodic Table and Atomic Structure
The relationship between the electron configuration predicted by the quantum mechanical
model of the atom and the periodic table was vital to the acceptance of quantum
mechanics as a theory. The coloring of regions in this figure divides the table into four
blocks of elements. The elements in each block are similar in that the electron in the
highest energy orbital comes from the same subshell. Thus all the elements in the section

orbital. These are sometimes referred to as the s block. The green section
at the far right of the table is the p block because according to the aufbau principle, the
last orbital occupied is a p orbital. The transition metals are d-block elements (shown in
purple), and the lanthanides and actinides make up the f block (shown in yellow).
Because of this structure, we can use the periodic table to determine electron
configurations for most elements. (A few exceptions arise, mainly among the transition
metals.) We find the element of interest in the periodic table and write its core
electrons using the shorthand notation with the previous rare gas element. Then
we determine the valence electrons by noting where the element sits within its own
period in the table.

Electronic Configuration

2nd Chapter
Polymorphism
“Poly” means many and “morphism” means forms or shaps. The word polymorphism means
having many forms. Polymorphism is the ability of an object to take on many forms.... Real
life example of polymorphism: A person at the same time can have different characteristic.
Like a man at the same time is a father, a husband, an employee. So the same person posses
different behavior in different situations. This is called polymorphism.
In the crystallographic context, crystal polymorphism, refers to the ability of a certain
compound to exist in different crystallographic structures, resulting from different packing
arrangements of its molecules in the crystal structure
polymorphism, in crystallography, the condition in which a solid chemical compound exists in
more than one crystalline form; the forms differ somewhat in physical and, sometimes,
chemical properties, although their solutions and vapours are identical.
Polymorphism and allotropic forms. Crystallography basics

Allotropic
The existence of different crystalline or molecular forms of elements is called allotropy,
although it has been suggested that the meaning of allotropy should be restricted to
different molecular forms of an element, such as oxygen (O2) and ozone (O3), and that
polymorphism be applied to different crystalline forms of the same species, whether
a compound or an element. Differences in the crystalline forms of many elements
and compounds were discovered during the 1820s
Among polymorphs of certain compounds, one is more stable than the others under all
conditions; in the cases of other compounds, one polymorph is stable within a particular
range of temperature and pressure while another is stable under a different set of
conditions. In either circumstance, the rate at which a less stable polymorph becomes
more stable often is so low that an intrinsically unstable form may persist indefinitely. As
an example of the first class, calcium carbonate has an orthorhombic form (i.e., having
three unequal crystalline axes at right angles to each other) called aragonite and a

hexagonal form (having three equal axes intersecting at angles of 60 degrees and a
fourth axis at right angles to these three) called calcite. Calcite is the stabler form;
aragonite changes into calcite rapidly at temperatures around 470° C (about 880° F) but
very slowly at room temperatures. The second class is represented by silica, which has
three forms—quartz, tridymite, and cristobalite—each of which is stable only in its
particular range of temperature and pressure, the others slowly changing into the stable
modification.
Hexagonal Cube

Isomorphism: Compound having same shape

3nd Chapter
Metal
Any of a class of substances characterized by high electrical and thermal conductivity as well
as by malleability, ductility, and high reflectivity of light.
Approximately three-quarters of all known chemical elements are metals. The most
abundant varieties in the Earth’s crust are aluminum, iron, calcium, sodium, potassium,
and magnesium. The vast majority of metals are found in ores (mineral-bearing substances),
but a few such as copper, gold, platinum, and silver frequently occur in the free state because
they do not readily react with other elements.
Metals are malleable, meaning they can be formed into useful shapes or foils. They are
ductile, meaning they can be pulled into wires. Metals are good conductors of electricity and
heat. How does the bonding in metals help explain these properties? Can the inclusion of
metal atoms inside a nanotube provide the same properties? By looking at a model of
metallic bonding, we can gain significant insight into these questions.
Metals and Ceramics.

A metal is a material that, when freshly prepared, polished, or fractured, shows a lustrous
appearance, and conducts electricity and heat relatively well. Metals are
typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into
wires). A metal may be a chemical element such as iron; an alloy such as stainless steel; or a
molecular compound such as polymeric sulfur nitride.
In physics, a metal is generally regarded as any substance capable of conducting electricity at
a temperature of absolute zero.[1] Many elements and compounds that are not normally
classified as metals become metallic under high pressures. For example, the
nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand
times atmospheric pressure. Equally, some materials regarded as metals can become
nonmetals. Sodium, for example, becomes a nonmetal at pressure of just under two million
times atmospheric pressure.
In chemistry, two elements that would otherwise qualify (in physics) as brittle metals—
arsenic and antimony—are commonly instead recognised as metalloids due to their
chemistry (predominantly non-metallic for arsenic, and balanced between metallicity and
nonmetallicity for antimony). Around 95 of the 118 elements in the periodic table are metals
(or are likely to be such). The number is inexact as the boundaries between
metals, nonmetals, and metalloids fluctuate slightly due to a lack of universally accepted

definitions of the categories involved.
In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star
that are heavier than helium, and not just traditional metals. In this sense the first four
"metals" collecting in stellar cores through nucleosynthesis are carbon, nitrogen, oxygen,
and neon, all of which are strictly non-metals in chemistry. A star fuses lighter atoms, mostly
hydrogen and helium, into heavier atoms over its lifetime. Used in that sense,
the metallicity of an astronomical object is the proportion of its matter made up of the
heavier chemical elements.[2][3]
Metals, as chemical elements, comprise 25% of the Earth's crust and are present in many
aspects of modern life. The strength and resilience of some metals has led to their frequent
use in, for example, high-rise building and bridge construction, as well as most vehicles,
many home appliances, tools, pipes, and railroad tracks. Precious metals were historically
used as coinage, but in the modern era, coinage metals have extended to at least 23 of the
chemical elements.[4]

The history of refined metals is thought to begin with the use of copper about 11,000 years
ago. Gold, silver, iron (as meteoric iron), lead, and brass were likewise in use before the first
known appearance of bronze in the 5th millennium BCE. Subsequent developments include
the production of early forms of steel; the discovery of sodium—the first light metal—in
1809; the rise of modern alloy steels; and, since the end of World War II, the development of
more sophisticated alloys.

Metals Properties:
Form and structure:
Metals are shiny and lustrous, at least when freshly prepared, polished, or fractured. Sheets
of metal thicker than a few micrometres appear opaque, but gold leaf transmits green light.
The solid or liquid state of metals largely originates in the capacity of the metal atoms
involved to readily lose their outer shell electrons. Broadly, the forces holding an individual
atom's outer shell electrons in place are weaker than the attractive forces on the same
electrons arising from interactions between the atoms in the solid or liquid metal. The
electrons involved become delocalised and the atomic structure of a metal can effectively be
visualised as a collection of atoms embedded in a cloud of relatively mobile electrons. This
type of interaction is called a metallic bond.[5] The strength of metallic bonds for different
elemental metals reaches a maximum around the center of the transition metal series, as
these elements have large numbers of delocalized electrons
Although most elemental metals have higher densities than most nonmetals,[5] there is a
wide variation in their densities, lithium being the least dense (0.534 g/cm3)
and osmium (22.59 g/cm3) the most dense. Magnesium, aluminum and titanium are light
metals of significant commercial importance. Their respective densities of 1.7, 2.7 and

Metals Properties:
Form and structure:
4.5 g/cm3 can be compared to those of the older structural metals, like iron at 7.9 and
copper at 8.9 g/cm3. An iron ball would thus weigh about as much as three aluminum balls
of equal volume.
High melting point: Most metals have high melting points and all except mercury are solid at
room temperature.
Sonorous: Metals often make a ringing sound when hit.
Reactivity: Some metals will undergo a chemical change (reaction), by themselves or with
other elements, and release energy. These metals are never found in a pure form, and are
difficult to separate from the minerals. Potassium and sodium are the most reactive metals.
They react violently with air and water; potassium will ignite on contact with water!
Other metals don’t react at all with other metals. This means they can be found in a pure
form (examples are gold and platinum). Because copper is relatively inexpensive and has a
low reactivity, it’s useful for making pipes and wiring.

Five groups of metals:
Noble Metals are found as pure metals because they are nonreactive and don’t combine
with other elements to form compounds. Because they are so nonreactive, they don’t
corrode easily. This makes them ideal for jewelry and coins. Noble metals include copper,
palladium, silver, platinum, and gold.
Alkali Metals are very reactive. They have low melting points and are soft enough to be cut
with a knife. Potassium and sodium are two alkali metals.
Alkaline Earth Metals are found in compounds with many different minerals. They are less
reactive than alkali metals, as well as harder, and have higher melting points. This group
includes calcium, magnesium, and barium.
Transition Metals are what we usually think of when we think of metals. They are hard and
shiny, strong, and easy to shape. They are used for many industrial purposes. This group
includes iron, gold, silver, chromium, nickel, and copper, some of which are also noble
metals.
Poor Metals are fairly soft, and most are not used very much by themselves. They become
very useful when added to other substances, though. Poor metals include aluminum, gallium,
tin, thallium, antimony, and bismuth.

Alloys: Strong Combinations
The properties of these different metals can be combined by mixing two or more of them
together. The resulting substance is called an alloy. Some of our most useful building
materials are actually alloys. Steel, for example, is a mixture of iron and small amounts of
carbon and other elements; a combination that is both strong and easy to use. (Add
chromium and you get stainless steel. Other alloys like brass (copper and zinc) and bronze
(copper and tin) are easy to shape and beautiful to look at. Bronze is also used frequently in
ship-building because it is resistant to corrosion from sea water.
Titanium is much lighter and less dense than steel, but as strong; and although heavier than
aluminum, it’s also twice as strong. It’s also very resistant to corrosion. All these factors make
it an excellent alloy material. Titanium alloys are used in aircraft, ships, and spacecraft, as
well as paints, bicycles, and even laptop computers!
Gold, as a pure metal, is so soft that it is always mixed with another metal (usually silver,
copper, or zinc) when it’s made into jewelry. The purity of gold is measured in karats. The
purest you can get in jewelry is 24 karats, which is about 99.7% pure gold. Gold can also be
mixed with other metals to change its color; white gold, which is popular for jewelry, is an
alloy of gold and platinum or palladium.

Metal from Ore
Ores are rocks or minerals from which a valuable substance – usually metal – can be
extracted. Some common ores include galena (lead ore), bornite and malachite (copper),
cinnabar (mercury), and bauxite (aluminum). The most common iron ores are magnetite and
hematite (a rusty-colored mineral formed by iron and oxygen), which both contain about
70% iron.
There are several processes for refining iron from ore. The older process is to burn iron ore
with charcoal (carbon) and oxygen provided by bellows. The carbon and oxygen, including
the oxygen in the ore, combine and leave the iron. However, the iron does not get hot
enough to melt completely and it contains silicates left over from the ore. It can be heated
and hammered out to form wrought iron.
The more modern process uses a blast furnace to heat iron ore, limestone, and coke (a coal
product). The resulting reactions separate out the iron from the oxygen in the ore. This ‘pig
iron’ needs to be further mixed to create wrought iron. It can also be used for another
important purpose: when heated with carbon and other elements, it becomes a stronger
metal called steel.

Corrosion: Process & Prevention
When oxygen reacts with a metal, it forms an oxide on the surface of the metal. In some
metals, like aluminum, this is a good thing. The oxide provides a protective layer that keeps
the metal from corroding further.
Iron and steel, on the other hand, have serious problems if they are not treated to prevent
corrosion. The reddish oxide layer that forms on iron or steel when it reacts with oxygen is
called rust. The rust layer continually flakes away, exposing more of the metal to corrosion
until the metal is eventually eaten through
One common way to protect iron is to coat it with special paint that keeps oxygen from
reacting with the metal underneath the paint. Another method is galvanization: in this
process, steel is coated with zinc. The oxygen, water molecules, and carbon dioxide in the air
react with the zinc, forming a layer of zinc carbonate that protects from corrosion. Look
around your house, yard, and garage for examples of corrosion as well as galvanization and
other means of protecting metal from rust.

Ceramics.
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials
made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high
temperature. Common examples are earthenware, porcelain, and brick.
The earliest ceramics made by humans were pottery objects (pots or vessels)
or figurines made from clay, either by itself or mixed with other materials like silica,
hardened and sintered in fire. Later, ceramics were glazed and fired to create smooth,
colored surfaces, decreasing porosity through the use of glassy, amorphous ceramic coatings
on top of the crystalline ceramic surface. Ceramics now include domestic, industrial and
building products, as well as a wide ranic materials were developed for use in advanced
ceramic engineering, such as in semiconductors.
The word "ceramic" comes from the Greek word (keramikos), "of pottery" or "for
pottery", from κέραμος (keramos), "potter's clay, tile, pottery".

Ceramics.
Ceramic material is an inorganic, non-metallic oxide, nitride, or carbide material. Some
elements, such as carbon or silicon, may be considered ceramics. Ceramic materials are
brittle, hard, strong in compression, and weak in shearing and tension. They withstand
chemical erosion that occurs in other materials subjected to acidic or caustic environments.
Ceramics generally can withstand very high temperatures, ranging from 1,000 °C to 1,600 °C
(1,800 °F to 3,000 °F).
The crystallinity of ceramic materials varies widely. Most often, fired ceramics are
either vitrified (glass) or semi-vitrified as is the case with earthenware, stoneware, and
porcelain. Varying crystallinity and electron composition in the ionic and covalent bonds
cause most ceramic materials to be good thermal and electrical insulators (researched
in ceramic engineering). With such a large range of possible options for the
composition/structure of a ceramic (nearly all of the elements, nearly all types of bonding,
and all levels of crystallinity), the breadth of the subject is vast, and identifiable attributes
(hardness, toughness, electrical conductivity) are difficult to specify for the group as a whole.
General properties such as high melting temperature, high hardness, poor conductivity,
high moduli of elasticity, chemical resistance and low ductility are the norm, with known
exceptions to each of these rules

Ceramics.
(piezoelectric ceramics, glass transition temperature, superconductive ceramics).
composites, such as fiberglass and carbon fiber, while containing ceramic materials are not
considered to be part of the ceramic family.
Highly oriented crystalline ceramic materials are not amenable to a great range of
processing. Methods for dealing with them tend to fall into one of two categories – either
make the ceramic in the desired shape, by reaction in situ, or by "forming" powders into the
desired shape, and then form into a solid body. Ceramic forming techniques include shaping
by hand (sometimes including a rotation process called "throwing"), slip casting, tape
casting (used for making very thin ceramic capacitors), injection molding, dry pressing, and
other variations.
Many ceramics experts do not consider materials with amorphous (noncrystalline) character
(i.e., glass) to be ceramics even though glassmaking involves several steps of the ceramic
process and its mechanical properties are similar to ceramic materials. However, heat
treatments can convert glass into a semi-crystalline material known as glass-ceramic
Traditional ceramic raw materials include clay minerals such as kaolinite, whereas more
recent materials include aluminum oxide, more commonly known as alumina. The modern

Ceramics.
ceramic materials, which are classified as advanced ceramics, include silicon
carbide and tungsten carbide. Both are valued for their abrasion resistance and hence find
use in applications such as the wear plates of crushing equipment in mining operations.
Advanced ceramics are also used in the medicine, electrical, electronics industries, and body
armor.
Properties
The physical properties of any ceramic substance are a direct result of its crystalline structure
and chemical composition. Solid-state chemistry reveals the fundamental connection
between microstructure and properties, such as localized density variations, grain size
distribution, type of porosity, and second-phase content, which can all be correlated with
ceramic properties such as mechanical strength, hardness, toughness, dielectric constant,
and the optical properties exhibited by transparent materials.
Ceramography is the art and science of preparation, examination, and evaluation of ceramic
microstructures. Evaluation and characterization of ceramic microstructures are often
implemented on similar spatial scales to that used commonly in the emerging field of
nanotechnology: from tens of ångstroms (Å) to tens of micrometers (µm). This is typically

Ceramics.
carbide and tungsten carbide. somewhere between the minimum wavelength of visible light
and the resolution limit of the naked eye.
The microstructure includes most grains, secondary phases, grain boundaries, pores, micro-
cracks, structural defects, and hardness micro indentions. Most bulk mechanical, optical,
thermal, electrical, and magnetic properties are significantly affected by the observed
microstructure. The fabrication method and process conditions are generally indicated by the
microstructure. The root cause of many ceramic failures is evident in the cleaved and
polished microstructure. Physical properties which constitute the field of materials
science and engineering include the following:
Mechanical properties
Mechanical properties are important in structural and building materials as well as textile
fabrics. In modern materials science, fracture mechanics is an important tool in improving
the mechanical performance of materials and components. It applies
the physics of stress and strain, in particular the theories of elasticity and plasticity, to the
microscopic crystallographic defects found in real materials in order to predict the
macroscopic mechanical failure of bodies. Fractography is widely used with fracture

Ceramics.
mechanics to understand the causes of failures and also verify the
theoretical failure predictions with real-life failures.
Ceramic materials are usually ionic or covalent bonded materials. A material held together by
either type of bond will tend to fracture before any plastic deformation takes place, which
results in poor toughness in these materials. Additionally, because these materials tend to be
porous, the pores and other microscopic imperfections act as stress concentrators,
decreasing the toughness further, and reducing the tensile strength. These combine to
give catastrophic failures, as opposed to the more ductile failure modes of metals.
These materials do show plastic deformation. However, because of the rigid structure of
crystalline material, there are very few available slip systems for dislocations to move, and so
they deform very slowly.
To overcome the brittle behavior, ceramic material development has introduced the class
of ceramic matrix composite materials, in which ceramic fibers are embedded and with
specific coatings are forming fiber bridges across any crack. This mechanism substantially
increases the fracture toughness of such ceramics. Ceramic disc brakes are an example of
using a ceramic matrix composite material manufactured with a specific process

Ceramics.
Ice-templating for enhanced mechanical properties
If ceramic is subjected to substantial mechanical loading, it can undergo a process called ice-
templating, which allows some control of the microstructure of the ceramic product and
therefore some control of the mechanical properties. Ceramic engineers use this technique
to tune the mechanical properties to their desired application. Specifically, strength is
increased, when this technique is employed. Ice templating allows the creation of
macroscopic pores in a unidirectional arrangement. The applications of this oxide
strengthening technique are important for solid oxide fuel cells and water filtration devices.
To process a sample through ice templating, an aqueous colloidal suspension is prepared to
contain the dissolved ceramic powder evenly dispersed throughout the colloid, for
example Yttria-stabilized zirconia (YSZ). The solution is then cooled from the bottom to the
top on a platform that allows for unidirectional cooling. This forces ice crystals to grow in
compliance with the unidirectional cooling and these ice crystals force the dissolved YSZ
particles to the solidification front of the solid-liquid interphase boundary, resulting in pure
ice crystals lined up unidirectionally alongside concentrated pockets of colloidal particles.
The sample is then simultaneously heated and the pressure is reduced enough to force the

Ceramics.
ice crystals to sublimate (change the form) and the YSZ pockets begin to anneal together to
form macroscopically aligned ceramic microstructures. The sample is then further sintered to
complete the evaporation of the residual water and the final consolidation of the ceramic
microstructure.
During ice-templating, a few variables can be controlled to influence the pore size and
morphology of the microstructure. These important variables are the initial solids loading of
the colloid, the cooling rate, the sintering temperature and duration, and the use of certain
additives which can influence the microstructural morphology during the process. A good
understanding of these parameters is essential to understanding the relationships between
processing, microstructure, and mechanical properties of unequal porous materials

Ceramics.
Electrical properties
Semiconductors
Some ceramics are semiconductors. Most of these are transition metal oxides that are II-VI
semiconductors, such as zinc oxide. While there are prospects of mass-producing blue LEDs
(ight-emitting diode) from zinc oxide, ceramicists are most interested in the electrical
properties that show grain boundary effects. One of the most widely used of these is the
varistor (semiconductor diode with resistance dependent). These are devices that exhibit the
property that resistance drops sharply at a certain threshold voltage. Once the voltage across
the device reaches the threshold, there is a breakdown of the electrical structure in the
vicinity of the grain boundaries, which results in its electrical resistance dropping from
several megohms down to a few hundred ohms. The major advantage of these is that they
can dissipate a lot of energy, and they self-reset; after the voltage across the device drops
below the threshold, its resistance returns to being high. This makes them ideal for surge-
protection applications; as there is control over the threshold voltage and energy tolerance,
they find use in all sorts of applications. The best demonstration of their ability can be found
in electrical substations, where they are employed to protect the infrastructure

Ceramics.
low maintenance, and do not appreciably degrade from use, making them virtually ideal
devices for this application. Semiconducting ceramics are also employed as gas sensors.
When various gases are passed over a polycrystalline ceramic, its electrical resistance
changes. With tuning to the possible gas mixtures, very inexpensive devices can be
produced.
Superconductivity
Under some conditions, such as extremely low temperature, some ceramics exhibit high-
temperature superconductivity.The reason for this is not understood, but there are two
major families of superconducting ceramics
Ferroelectricity (reversal of flow) and supersets
Piezoelectricity, a link between electrical and mechanical response, is exhibited by a large
number of ceramic materials, including the quartz used to measure time in watches and
other electronics. Such devices use both properties of piezoelectrics, using electricity to
produce a mechanical motion (powering the device) and then using this mechanical motion
to produce electricity (generating a signal). The unit of time measured is the natural interval
required for electricity to be converted into mechanical energy and back again.

Ceramics.
The piezoelectric effect is generally stronger in materials that also exhibit pyroelectricity
(generate a temporary voltage), and all pyroelectric materials are also piezoelectric. These
materials can be used to inter-convert between thermal, mechanical, or electrical energy; for
instance, after synthesis in a furnace, a pyroelectric crystal allowed to cool under no applied
stress generally builds up a static charge of thousands of volts. Such materials are used
in motion sensors, where the tiny rise in temperature from a warm body entering the room is
enough to produce a measurable voltage in the crystal.
In turn, pyroelectricity is seen most strongly in materials that also display the ferroelectric
effect, in which a stable electric dipole can be oriented or reversed by applying an
electrostatic field. Pyroelectricity is also a necessary consequence of ferroelectricity. This can
be used to store information in ferroelectric capacitors, elements of ferroelectric RAM.
The most common such materials are lead zirconate titanate and barium titanate. Aside from
the uses mentioned above, their strong piezoelectric response is exploited in the design of
high-frequency loudspeakers, transducers for sonar.

Ceramics.
Positive thermal coefficient
Temperature increases can cause grain boundaries to suddenly become insulating in some
semiconducting ceramic materials, mostly mixtures of heavy metal titanates. The critical
transition temperature can be adjusted over a wide range by variations in chemistry. In such
materials, current will pass through the material until joule heating brings it to the transition
temperature, at which point the circuit will be broken and current flow will cease. Such
ceramics are used as self-controlled heating elements in, for example, the rear-window
defrost circuits of automobiles.
At the transition temperature, the material's dielectric response becomes theoretically
infinite. While a lack of temperature control would rule out any practical use of the material
near its critical temperature, the dielectric effect remains exceptionally strong even at much
higher temperatures.

Ceramics.
Optical properties
Optically transparent materials focus on the response of a material to incoming light waves
of a range of wavelengths. Frequency selective optical filters can be utilized to alter or
enhance the brightness and contrast of a digital image. Guided lightwave transmission via
frequency selective waveguides involves the emerging field of fiber optics and the ability of
certain glassy compositions as a transmission medium for a range of frequencies
simultaneously (multi-mode optical fiber) with little or no interference between
competing wavelengths or frequencies. This resonant mode of energy and data
transmission via electromagnetic (light) wave propagation, though low powered, is virtually
lossless. Optical waveguides are used as components in Integrated optical circuits (e.g. light-
emitting diodes, LEDs) or as the transmission medium in local and long haul optical
communication systems. Also of value to the emerging materials scientist is the sensitivity of
materials to radiation in the thermal infrared (IR) portion of the electromagnetic spectrum.
This heat-seeking ability is responsible for such diverse optical phenomena as Night-
vision and IR luminescence.
Thus, there is an increasing need in the military sector for high-strength, robust materials

Ceramics.
Optical properties
1. Barium titanate: (often mixed with strontium titanate) displays ferroelectricity, meaning
that its mechanical, electrical, and thermal responses are c
2. Sialon (Silicon Aluminium Oxynitride) has high strength; resistance to thermal shock,
chemical and wear resistance, and low density. These ceramics are used in non-ferrous
molten metal handling, weld pins, and the chemical industry.
3.Silicon carbide (SiC) is used as a susceptor in microwave furnaces, a commonly used
abrasive, and as a refractory material.
4.Silicon nitride (Si3N4) is used as an abrasive powder.
5.Steatite (magnesium silicates) is used as an electrical insulator.
6.Titanium carbide Used in space shuttle re-entry shields and scratchproof watches.
7.Uranium oxide (UO2), used as fuel in nuclear reactors.
8.Yttrium barium copper oxide (YBa2Cu3O7−x), another high temperature superconductor.

Ceramics.
Optical properties
9. Zinc oxide (ZnO), which is a semiconductor, and used in the construction of varistors.
10.Zirconium dioxide (zirconia), which in pure form undergoes many phase
changes between room temperature and practical sintering temperatures, can be chemically
"stabilized" in several different forms. Its high oxygen ion conductivity recommends it for use
in fuel cells and automotive oxygen sensors. In another variant, metastable structures can
impart transformation toughening for mechanical applications; most ceramic knife blades are
made of this material. Partially stabilised zirconia (PSZ) is much less brittle than other
ceramics and is used for metal forming tools, valves and liners, abrasive slurries, kitchen
knives and bearings subject to severe abrasion.

Ceramics.
usage
Ceramic products are usually divided into four main types; these are shown below with some
examples:
1.Structural, including bricks, pipes, floor and roof tiles
2. Refractories, such as kiln linings, gas fire radiants, steel and glass making crucibles
3. Whitewares, including tableware, cookware, wall tiles, pottery products and sanitary ware
4.Technical, also known as engineering, advanced, special, and fine ceramics. Such items
include:
gas burner nozzles, ballistic protection, vehicle armor, nuclear fuel uranium oxide pellets, biomedical
implants ,coatings of jet engine turbine blades ,Ceramic matrix composite gas turbine parts ,Reinforced
carbon–carbon ceramic disc brakes ,missile nose cones ,bearing (mechanical)
tiles used in the Space Shuttle program

Ceramics.
Applications:
1.Knife blades: blade of a ceramic knife will stay sharp for much longer than that of a steel
knife, although it is more brittle and susceptible to breaking.
2.Carbon-ceramic brake disks: for vehicles are resistant to brake fade at high temperatures.
3."Advanced composite ceramic and metal matrices" have been designed for most
modern armoured fighting vehicles because they offer superior penetrating resistance
against shaped charges (HEAT rounds) and kinetic energy penetrators.
4."Ceramics such as alumina and boron carbide" have been used in ballistic armored
vests to repel high-velocity rifle fire. Such plates are known commonly as small arms
protective inserts, or SAPIs. Similar material is used to protect the cockpits of some military
airplanes, because of the low weight of the material.
5.Ceramics can be used in place of steel for ball bearings. Their higher hardness means they
are much less susceptible to wear and typically last for triple the lifetime of a steel part. They
also deform less under load, meaning they have less contact with the bearing retainer walls
and can roll faster. In very high-speed applications, heat from friction during rolling can cause

Ceramics.
Applications:
problems for metal bearings, which are reduced by the use of ceramics. Ceramics are also
more chemically resistant and can be used in wet environments where steel bearings would
rust. In some cases, their electricity-insulating properties may also be valuable in bearings.
Two drawbacks to ceramic bearings are a significantly higher cost and susceptibility to
damage under shock loads.
6.In the early 1980s, Toyota researched production of an adiabatic engine using ceramic
components in the hot gas area. The ceramics would have allowed temperatures of over
1650°C. The expected advantages would have been lighter materials and a smaller cooling
system (or no need for one at all), leading to a major weight reduction. The expected
increase of fuel efficiency of the engine (caused by the higher temperature, as shown
by Carnot's theorem) could not be verified experimentally; it was found that the heat
transfer on the hot ceramic cylinder walls was higher than the transfer to a cooler metal wall
as the cooler gas film on the metal surface works as a thermal insulator. Thus, despite all of
these desirable properties, such engines have not succeeded in production because of costs
for the ceramic components and the limited advantages. (Small imperfections in the ceramic

Ceramics.
Applications:
material with its low fracture toughness lead to cracks, which can lead to potentially
dangerous equipment failure.) Such engines are possible in laboratory settings, but mass
production is not feasible with current technology.
7.Work is being done in developing ceramic parts for gas turbine engines. Currently, even
blades made of advanced metal alloys used in the engines' hot section require cooling and
careful limiting of operating temperatures. Turbine engines made with ceramics could
operate more efficiently, giving aircraft greater range and payload for a set amount of fuel.
8.Recent advances have been made in ceramics which include bioceramics, such as dental
implants and synthetic bones. Hydroxyapatite, the natural mineral component of bone, has
been made synthetically from several biological and chemical sources and can be formed into
ceramic materials. Orthopedic implants coated with these materials bond readily to bone
and other tissues in the body without rejection or inflammatory reactions so are of great
interest for gene delivery and tissue engineering scaffolds. Most hydroxyapatite ceramics are
very porous and lack mechanical strength, and are used to coat metal orthopedic devices to
aid in forming a bond to bone or as bone fillers. They are also used as fillers for orthopedic

Ceramics.
plastic screws to aid in reducing inflammation and increase the absorption of these plastic
materials. Work is being done to make strong, fully dense nanocrystalline hydroxyapatite
ceramic materials for orthopedic weight bearing devices, replacing foreign metal and plastic
orthopedic materials with a synthetic, but naturally occurring bone mineral. Ultimately, these
ceramic materials may be used as bone replacements or with the incorporation of
protein collagens, synthetic bones.
8.Durable actinide-containing ceramic materials have many applications such as in nuclear
fuels for burning excess Pu and in chemically-inert sources of alpha irradiation for power
supply of unmanned space vehicles or to produce electricity for microelectronic devices.
Both use and disposal of radioactive actinides require their immobilization in a durable host
material. Nuclear waste long-lived radionuclides such as actinides are immobilized using
chemically-durable crystalline materials based on polycrystalline ceramics and large single
crystals.
10.High-tech ceramic is used in watchmaking for producing watch cases. The material is
valued by watchmakers for its lightweight, scratch resistance, durability, and smooth
touch. IWC is one of the brands that initiated the use of ceramic in watchmaking.[19]

4Th Chapter
Energy and Chemistry
Energy
Energy is the capacity of a physical system to do work. The common symbol for energy is the
uppercase letter E. The standard unit is the joule, symbolized by J. One joule (1 J) is the
energy resulting from the equivalent of one newton (1 N) of force acting over one meter (1
m) of displacement. There are two main forms of energy, called potential energy and kinetic
energy.
Potential energy, sometimes symbolized U, is energy stored in a system. A stationary object
in a gravitational field, or a stationary charged particle in an electric field, has potential
energy.
Kinetic energy is observable as motion of an object, particle, or set of particles. Examples
include the falling of an object in a gravitational field, the motion of a charged particle in an
electric field, and the rapid motion of atoms or molecules when an object is at a temperature
above zero Kelvin.
Thermo-chemistry

4Th Chapter
Energy
Matter is equivalent to energy in the sense that the two are related by the Einstein equation:
E = mc2
where E is the energy in joules, m is the mass in kilograms, and c is the speed of light, equal
to approximately 2.99792 x 108 meters per second.
In electrical circuits, energy is a measure of power expended over time. In this sense, one
joule (1 J) is equivalent to one watt (1 W) dissipated or radiated for one second (1 s). A
common unit of energy in electric utilities is the kilowatt-hour (kWh), which is the equivalent
of one kilowatt (kW) dissipated or expended for one hour (1 h). Because 1 kW = 1000 W and
1 h = 3600 s, 1 kWh = 3.6 x 106 J.
Heat energy is occasionally specified in British thermal units (Btu) by nonscientists, where 1
Btu is approximately equal to 1055 J. The heating or cooling capability of a climate-control
system may be quoted in Btu, but this is technically a misuse of the term. In this sense, the
system manufacturer or vendor is actually referring to Btu per hour (Btu/h), a measure of
heating or cooling power.
Thermo-chemistry

4Th Chapter
Thermo-chemistry
Thermochemistry is the study of the heat energy which is associated with chemical
reactions and/or physical transformations. A reaction may release or absorb energy, and a
phase change may do the same, such as in melting and boiling. Thermochemistry focuses on
these energy changes, particularly on the system's energy exchange with its surroundings.
Thermochemistry is useful in predicting reactant and product quantities throughout the
course of a given reaction. In combination with entropy determinations, it is also used to
predict whether a reaction is spontaneous (immediate) (produced product under given
condition) or non-spontaneous, favorable or unfavorable.
Endothermic reactions absorb heat, while exothermic reactions release heat.
Thermochemistry combine into one the concepts of thermodynamics with the concept of
energy in the form of chemical bonds. The subject commonly includes calculations of such
quantities as heat capacity, heat of combustion, heat of formation, enthalpy, entropy, free
energy, and calories.
Thermo-chemistry

4Th Chapter
Heat and Work
Heat is the flow of energy between two objects, from the warmer one to the cooler one,
because of a difference in their temperatures. Thus if we are speaking carefully, heat is a
process and not a quantity. Although we routinely hear statements such as “turn up the
heat,” heat is not an entity we can pump into a room or a cup of coffee. An object does not
possess heat. In a strictly scientific sense, a furnace does not produce heat but rather a body
of warm air or hot water that has a higher temperature than the cool air in a room. What
emerges from the vent on the floor is not “heat,” but warm air. Although these distinctions
are essentially meaningful, they can be very important in many cases.
Work is the transfer of energy accomplished by a force moving a mass some distance against
resistance. Lifting a set of roller coaster cars up a hill against the pull of gravity is an example
of work. When we consider macroscopic examples, we are typically viewing work in terms of
mechanical energy. Work, however, encompasses a wider range of phenomena than just
mechanical movement of macroscopic objects. The most common type of work we will
Thermo-chemistry

4Th Chapter
Heat and Work
encounter in chemical processes is pressure-volume work (PV-work). When a gas expands, it
can do work. If an inflated balloon is released before it is tied off, it flies around as the gas
inside the balloon expands into the large volume of the room. Because the flying balloon has
mass, it is easy to see that the expanding gas is doing work on the balloon: this is pressure-
volume work.
For a more productive example of work being done by a chemical reaction, we might look at
the burning of gasoline in a car engine. Gasoline is actually a complex mixture of
hydrocarbons. The energy needed to propel a car is released by the combustion of those
hydrocarbons in the engine cylinders.
Hydrocarbon + O2(g) : CO2(g) + H2O(g)
This combustion produces carbon dioxide and water vapor, and those gases do PV-work as
they expand against the piston in the cylinder. This PV-work is then transmitted through the
drive train to move the car.
Thermo-chemistry

4Th Chapter
Energy Transformation and Conservation of Energy
The multiple forms of energy are not all equally useful, so in many cases it is desirable to
transform energy from one form into another. For example, the lighting in room is provided
by electricity, but that electricity was probably generated by the release of chemical energy
through the combustion of coal. Chemical energy released as the coal burns and then
convert it to electrical energy. That electrical energy must then be conveyed to room, where
light bulbs convert it into radiant energy. The first and foremost constraint on energy
transformation is that total energy must be conserved. It need to define a number of terms.
The system is defined as the part of the universe that is being considered. The remainder of
the universe is referred to as the surroundings, even though it is not generally necessary to
consider everything else in the actual universe. These definitions assure that the system plus
the surroundings must equal the universe. The system and the surroundings are separated
by a boundary. In some cases, this boundary may be a physical container, and in others, it
might be a more abstract separation.
Thermo-chemistry

4Th Chapter
Once an appropriate choice of a system has been made, the concept of conservation of
energy immediately becomes useful. Because we said that heat and work are the only
possible forms of energy transfer, we can attribute the overall change in energy, E, of a
system to these two components. Heat is commonly designated as q and work as w, so we
can write ∆E = q + w (Change in internal Energy)
The symbol ∆ (delta) is introduced here as a notation meaning “the change in.” is always
defined as the difference between the final state and the initial state.
∆E = Efinal – Einitial
Convention dictates that energy transferred into a system is given a positive sign and energy
flowing out of a system carries a negative sign. Thus when heat flows into a system from the
surroundings, the value of q is positive, and when work is done on a system, the value of w is
positive. Conversely, when heat flows out of a system or work is done by the system on the
surroundings, q and w will be negative
Thermo-chemistry

4Th Chapter
EXAMPLE
If 515 J of heat is added to a gas that does 218 J of work as a result, what is the change
in the energy of the system?
Solution
Heat added TO the system means that q > 0, so q = +515 J.
Work done BY the system means that w < 0, so w = –218 J.
∆E = q + w = 515 J + (–218 J) = +297 J
Now ∆E = q + w (Change in internal Energy)
State that “Energy can be transformed from one form to another but cannot be created or
destroyed. This is known as the first law of thermodynamics.”
Which is called the Law of conservation of Energy.
Thermo-chemistry

4Th Chapter
Waste Energy
The combustion of gasoline is not inherently useful, but when the heat released is harnessed
in the engine of an automobile, the resulting work gets us where we need to go. All available
observations, however, point to the idea that it is impossible to convert heat completely to
work. The car’s engine gets hot when it runs. The heat that warms the engine does not
propel the car toward its destination. So a portion of the energy released by the combustion
of gasoline does not contribute to the desired work of moving the car. In terms of the energy
economy, this energy can be considered wasted.
One common way to obtain work from a system is to heat it: heat flows into the system and
the system does work. But in practice, the amount of heat flow will always exceed the
amount of useful work achieved. The excess heat may contribute to thermal pollution.
(Thermal pollution is the raising or lowering of water temperature in streams, lakes, or
oceans above or below normal seasonal ranges from the discharge of hot or cold waste
streams into the water.) The efficiency of conversion from heat to work can be expressed as a
percentage.
Thermo-chemistry

4Th Chapter
Waste Energy Table
Typical efficiencies of some common energy conversion devices
Device Energy Conversion Typical Efficiency (%)
Electric heater Electrical : thermal 100
Hair drier Electrical : thermal 100
Electric generator Mechanical : electrical 95
Electric motor (large) Electrical : mechanical 90
Battery Chemical : electrical 90
Steam boiler (power plant) Chemical : thermal 85
Home gas furnace Chemical : thermal 85
Home oil furnace Chemical : thermal 65
Electric motor (small) Electrical : mechanical 65
Home coal furnace Chemical : thermal 55
Steam turbine Thermal : mechanical 45
Gas turbine (aircraft) Chemical : mechanical 35
Gas turbine (industrial) Chemical : mechanical 30
Automobile engine Chemical : mechanical 25
Thermo-chemistry

4Th Chapter
Heat Capacity and Calorimetry
Heat Capacity
Different systems will absorb different amounts of energy (heat) based on three main factors:
the amount of material, the type of material, and the temperature change. The general
expression for Heat capacity is given as:
q = mc∆T
Where q is the heat capacity, m is mass of the material c is the specific heat of material and
∆T is the difference or change in temperature.
The specific heat is a physical property of a material that measures how much heat is
required to raise the temperature of one gram of that material by 1°C. Similarly, the molar
heat capacity is a physical property that describes how much heat is required to raise the
temperature of one mole of a substance by 1°C. So if we choose to express the amount of
material in terms of moles rather than mass, our equation changes only slightly.
q = ncp∆T OR q = ncv∆T
Thermo-chemistry

4Th Chapter
Calorimetry
Calorimetry is the term used to describe the measurement of heat flow (heat flow into or out
of a system). Experiments are carried out in devices called calorimeters. It is the process of
measuring the amount of heat released or absorbed during a chemical reaction. The heat
evolved or absorbed by the system of interest is determined by measuring the temperature
change in its surroundings. Every effort is made to isolate the calorimeter thermally,
preventing heat flow between the immediate surroundings and the rest of the universe. If
the instrument is thermally isolated from the rest of the universe, the only heat flow that
must be considered is that between the system being studied and the immediate
surroundings, whose temperature can be measured.
A two-step process is used to make a calorimetric measurement. The first step is calibration
in which a known amount of heat is generated in the apparatus. The second step is the actual
measurement, in which we determine the amount of heat absorbed or released in the
reaction of a known amount of material. The calibration can be done either by burning a
known amount of a well-characterized material or by resistive heating, in which a known
amount of current is passed through a wire that heats due to its electrical resistance.
Thermo-chemistry

4Th Chapter
Calorimetry
The heat capacity of the entire calorimeter may be obtained by measuring the change in
temperature of the surroundings resulting from a known heat input.
Known amount of heat = calorimeter constant × ∆T , Or q = Ccalorimeter × ∆T

4Th Chapter
Heat Capacity and Calorimetry
Calorimetry
Note that in contrast to our earlier equations relating q and ∆T, there is no mass or number
of moles term here for the quantity of material. The calorimeter constant is the heat capacity
of a particular object (or set of objects) rather than that of a material. It may help to think of
it as the heat capacity “per calorimeter” and then realize that we have just one calorimeter.
For someone who routinely uses the same calorimeter, this approach is much simpler than
the alternative, which would be to keep track of the masses of steel, water, and other
materials in the calorimeter. In the case of a bomb calorimeter, the calorimeter constant is
largely attributable to the water that surrounds the bomb but also includes the heat
capacities of the thermometer, the stirring system, and the bomb itself.
Thermo-chemistry

4Th Chapter
EXAMPLE
A calorimeter is to be used to compare the energy content of some fuels. In the calibration of
the calorimeter, an electrical resistance heater supplies 100.0 J of heat and a temperature
increase of 0.850°C is observed. Then 0.245 g of a particular fuel is burned in this same
calorimeter, and the temperature increases by 5.23°C. Calculate the energy density of this
fuel, which is the amount of energy liberated per gram of fuel burned.
Strategy :The calibration step allows us to determine the calorimeter constant. Once this is
known, the amount of heat evolved from the fuel can be determined by using Equation.
Finally, we divide this heat by the mass of fuel that generated it to arrive at the requested
energy density.
Solution
Step 1: Calibration
q = Ccalorimeter × ∆T
So Ccalorimeter = q/ ∆T
= 100.0 J/0.850°C
Ccalorimeter = 118 J/°C
Thermo-chemistry

4Th Chapter
EXAMPLE
Step 2: Determination of heat evolved by fuel
qcalorimeter = Ccalorimeter × ∆T
= 118 J/°C × 5.23°C
= 615 J
And
qfuel = –qcalorimeter = –615 J
Step 3: Calculation of the energy density
Energy density = –qfuel/m
= –(–615 J)/0.245 g
= 2510 J/g = 2.51 kJ/g
Discussion This problem illustrates the need to be careful with signs in thermodynamic
calculations. Because the burning of fuel releases heat, q for the fuel should be negative. The
energy density, though, would be reported as a positive number, resulting in the additional
negative sign in the final step.
Thermo-chemistry

4Th Chapter
Enthalpy
The enthalpy of a thermodynamic system is defined as the sum of its internal energy and the
product of its pressure and volume (work done)
By using the definition of internal energy , the change in internal energy ∆E equals the sum
of heat flow and work.
∆E = q + w
In chemical reactions, we usually need to consider only PV-work. When a gas expands, it
does an amount of work equal to P∆V on its surroundings. But if the expanding gas is our
system, we want w to be the work done on the gas, and that will be –P ∆V. So we can replace
w in the equation above with –P∆V.
∆E = q – P ∆V
If the volume is held constant, ∆V is zero, so the second term is zero. All that remains is
∆ E = qv
where subscript “v” denote that the equation is correct under constant volume conditions.
Thermo-chemistry

4Th Chapter
Enthalpy
If the experiment is at constant pressure, than above equation will became
H = E + PV
Where “H” is known as enthalpy which is the sum of its internal energy and the product of
its pressure and volume (work)
Working from this definition, we can show that the change in enthalpy (∆H) will be equal to
the heat flow under constant pressure conditions. From the above definition, the change in
enthalpy (∆H) must be
∆H = ∆E + ∆(PV)
We can expand this by substituting for ∆E using
∆H = (q – P ∆V ) + ∆(PV )
If the pressure is held constant, then the ∆(PV ) term will simply become P ∆V, giving
∆H = q – P ∆V + P ∆V
The second and third terms clearly cancel and leave the desired result.
∆H = qp
Thermo-chemistry

4Th Chapter
Enthalpy
The enthalpy change therefore equals the heat flow under constant pressure. (This is
denoted with a subscript “p”.)
Now we have two ways to define heat flow into a system, under two different sets of
conditions. For a process at constant volume, the measurable heat flow is equal to ∆E, the
change in internal energy. For a process at constant pressure, the measurable heat flow is
equal to the change in enthalpy, ∆H. A reaction carried out in a beaker in the chemistry
laboratory, for instance, occurs under constant pressure conditions (or very nearly so). Thus,
when we refer to the heat of a process, we are typically referring to a change in enthalpy, ∆H.
As in previous definitions, ∆H refers to Hfinal – Hinitial. When heat evolves from a system, the
process is said to be exothermic and the value of ∆H is less than zero. An exothermic process
feels hot: if you pick up the beaker in which an exothermic reaction is taking place, heat will
flow from the reacting system into your hand. Conversely, when heat is absorbed by the
system, the process is said to be endothermic, and the value of ∆H is greater than zero.
Endothermic processes feel cold because they draw heat from their surroundings.
Thermo-chemistry

4Th Chapter
Enthalpy
∆H of Phase Changes
Heat flow into a substance does not always raise its temperature. If heat flows into an ice
cube at 0°C, for example, the ice will melt to form liquid water at 0°C. (If heat continues to
flow into the resulting water, its temperature will begin to rise, of course.) How can the
temperature remain constant despite the influx of heat? To understand this, we need to
remember that intermolecular forces are more extensive in a solid than in a liquid. So as the
ice cube melts, energy must be expended to overcome some of the intermolecular
attractions. The internal energy of liquid water is higher than that of solid ice, even though
both are at the same temperature.
For similar reasons, there will be heat flow in any phase change. The names of phase changes
among solids, liquids, and gases are summarized in Figure. Because these phase changes
generally take place at constant pressure, the corresponding heat flows should be viewed as
changes in enthalpy. Some phase changes are so common that their enthalpy changes have
Thermo-chemistry

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