1) Colloids have particle sizes between 1-100 nm, are heterogeneous systems that cannot be filtered or separated by centrifugation, and include sols, emulsions, and gels.
2) Sols are dispersions where the dispersed phase is a solid and the dispersion medium is a liquid. They can be lyophilic or lyophobic.
3) Emulsions are dispersions where both phases are liquids, existing as oil-in-water or water-in-oil forms. Gels have a solid dispersion medium and liquid dispersed phase.
4) Colloids exhibit unique optical, kinetic, and electrical properties due to their intermediate size, including Tyndall effect, Brownian
Rheology is the science that study flow of fluids. Viscosity is the main parameter of flow. Newtonian & non newtonian are the two types of flow behavior according to newtons law of flow. non-newtonian flow can be plastic, pseudoplastic, dilatant, thixotropic, antithixotropic or rheopexy. viscosity can be determined by using various viscometers such as capillary viscometer, cup & bob viscometer, cone & plate viscometer, falling sphere viscometer, brookfield viscometer, etc. factors affeting viscosity are intrinsic, extrinsic or temperature dependence.
In this presentation:
Surface Tension
Interfacial Tension
Definition of inerfacial tension in different ways
Measurement of interfacial and surface tesion
Surface and Interfacial tension [Part-3(a)](Measurement of Surface and Inter...Ms. Pooja Bhandare
MEASUREMENT OF SURFACE AND INTERFACIAL TENSION
Capillary Rise Method, Drop Count and Weight Method.
Wilhelmy Plate Methods ,The DuNouy Ring Method.
Capillary Rise Method: Upward force due to surface tension: Drop count and Weight method Downward Force: Drop weight method: Drop count method
Solid State of matter,
Crystalline, Amorphous & Polymorphism Forms,
Classification of solid state of matter On the basis of Internal Structure,
PHYSICAL PHARMACEUTICS-I,
Habet,
B.Pharm,
Solubility of Drugs (PHYSICAL PHARMACEUTICS-I)Rakesh Mishra
Solubility expressions, mechanisms of solute solvent interactions,solubility parameters, factors influencing
solubility of drugs, diffusion principles in biological systems, Raoult’s law, real solutions. Partially miscible
liquids(Phase equilibria, Phase rule, One , two and three component systems, ternary phase
diagram, Critical solution temperature and applications). Distribution law, its limitations and
applications
Rheology is the science that study flow of fluids. Viscosity is the main parameter of flow. Newtonian & non newtonian are the two types of flow behavior according to newtons law of flow. non-newtonian flow can be plastic, pseudoplastic, dilatant, thixotropic, antithixotropic or rheopexy. viscosity can be determined by using various viscometers such as capillary viscometer, cup & bob viscometer, cone & plate viscometer, falling sphere viscometer, brookfield viscometer, etc. factors affeting viscosity are intrinsic, extrinsic or temperature dependence.
In this presentation:
Surface Tension
Interfacial Tension
Definition of inerfacial tension in different ways
Measurement of interfacial and surface tesion
Surface and Interfacial tension [Part-3(a)](Measurement of Surface and Inter...Ms. Pooja Bhandare
MEASUREMENT OF SURFACE AND INTERFACIAL TENSION
Capillary Rise Method, Drop Count and Weight Method.
Wilhelmy Plate Methods ,The DuNouy Ring Method.
Capillary Rise Method: Upward force due to surface tension: Drop count and Weight method Downward Force: Drop weight method: Drop count method
Solid State of matter,
Crystalline, Amorphous & Polymorphism Forms,
Classification of solid state of matter On the basis of Internal Structure,
PHYSICAL PHARMACEUTICS-I,
Habet,
B.Pharm,
Solubility of Drugs (PHYSICAL PHARMACEUTICS-I)Rakesh Mishra
Solubility expressions, mechanisms of solute solvent interactions,solubility parameters, factors influencing
solubility of drugs, diffusion principles in biological systems, Raoult’s law, real solutions. Partially miscible
liquids(Phase equilibria, Phase rule, One , two and three component systems, ternary phase
diagram, Critical solution temperature and applications). Distribution law, its limitations and
applications
Electro osmosis ,colligative propertries of colloids ,electrokinetic properti...Anand P P
electro osmosis.that topics deals with colloids and their one of the colligative properties that is electro kinetic property.under the electrokinetic colligative property of colloids consist 2 properties mainly electrophoresis and elecoosmosis.the electro osmosis have several application properties.the electroosmosis is mainly deals with the charge of colloidal system and their movements opposite charges.electrical double layer theory.
Colloids are crucial to both ordinary living and pharmacological formulations. the study of both big molecules
and intricately divided multiphase systems is known as colloidal science. the intersection of colloid and
surface science is the multi-phase system. a colloid is a mixture in which one material is suspended within
another substance and has insoluble particles scattered over a tiny scale. between genuine solutions and
suspensions, colloidal solutions or colloidal dispersions represent a middle ground. the dispersed phase of
colloids is distributed throughout the dispersion medium. in many facets of chemistry, colloidal chemistry
knowledge is necessary. this article provides information on what colloids are, their types, sizes, forms,
qualities, and uses.
Classification of dispersed systems & their general characteristics, size & shapes of colloidal particles, classification of colloids & comparative account of their general properties. Optical, kinetic & electrical properties. Effect of electrolytes, coacervation, peptization& protective action.
The following presentation is only for quick reference. I would advise you to read the theoretical aspects of the respective topic and then use this presentation for your last minute revision. I hope it helps you..!!
Mayur D. Chauhan
Crystallization is a separation process very commonly used in the industry of many different materials, from commercially very common chemicals to very specific ones. It also plays an important role in the pharmaceutical industry, as more than 90% of active pharmaceutical ingredients (API) are synthesized as a crystalline product. Crystallization may have a significant direct and indirect influence on the quality of a product; therefore, it is one of the most important purification and separation methods in the production of APIs.
Colloidal Dispersion, Its Types and Method of PreparationChitralekhaTherkar
Dispersion
Definition of Colloids
Shapes and Sizes of Colloids
Classification of Colloids
Properties of Colloids
1. Optical Properties.
2. Electrical Properties.
3. Kinetic Properties
Purification of Colloids
Method of Preparation of Colloids.
Physical Stability of Colloids.
Factors affecting Colloidal Dispersion.
Food: Food additives: Food preservatives, artificial sweeteners and antioxidants (definition and
examples, structures not required) – Structure of BHT, BHA and Ajinomoto - Commonly used permitted
and non-permitted food colours (structures not required) - Fast foods and junk foods & their health
effects - Artificial ripening of fruits and its health effects. Importance of milk, coconut water and Neera.
Cleansing Agents: Soaps - Saponification of lipids – Hard and soft soaps. Detergents (classification and
examples) – Cleansing action - Advantages and disadvantages of soaps and detergents.
Dyes: Definition – Requirements of a dye - Theories of colour and chemical constitution - Structure and
applications of Martius yellow, indigo and alizarin.
Petrochemicals: Name, carbon range and uses of fractions of petroleum distillation – Octane number –
Cetane number – Flash point. LPG and CNG: Composition and uses.
Pharmaceuticals: Drug - Chemical name, generic name and trade names with examples. Prodrug.
Antipyretics, analgesics, antibiotics, antacids, antiseptics, antihistamines and tranquilizers
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Toxic effects of heavy metals : Lead and Arsenicsanjana502982
Heavy metals are naturally occuring metallic chemical elements that have relatively high density, and are toxic at even low concentrations. All toxic metals are termed as heavy metals irrespective of their atomic mass and density, eg. arsenic, lead, mercury, cadmium, thallium, chromium, etc.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Salas, V. (2024) "John of St. Thomas (Poinsot) on the Science of Sacred Theol...Studia Poinsotiana
I Introduction
II Subalternation and Theology
III Theology and Dogmatic Declarations
IV The Mixed Principles of Theology
V Virtual Revelation: The Unity of Theology
VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
2. COLLOIDS
• True solution
0.1-1 nm is the molecular size
Homogeneous system
Cannot filter, cannot see through naked eyes or microscope,
wont settle down
• Suspension
A heterogeneous system, diameter > 100 nm.
Can filter, settle rapidly under gravity, no diffusion
• Colloid
Diameter 1-100 nm
Cannot filter, wont settle down , diffusion is very low
Colloids, Manju Sebastian, St. Mary's College
3. Colloidal solution
• A heterogeneous system consisting of 2 phases-dispersed
phase of colloidal particles and the dispersion medium of
the solvent or medium
Colloids, Manju Sebastian, St. Mary's
College
4. SOLS
• Dispersed phase solid-dispersion medium
liquid
• Eg: Colloidal suspension of starch, gelatin,
gold etc.
• Classification of sols based on dispersion
medium
– Hydrosol, Alcosol or Benzosol
• Classification based on affinity between phases
– Lyophilic (liquid loving) colloids and lyophobic
colloids (liquid hating)
Colloids, Manju Sebastian, St. Mary's
College
5. Differences between lyophilic and
lyophobic sols
Lyophilic sol
• Greater affinity between dispersed
phase and dispersion medium
• Very stable
• Can easily prepare by warming
• They are reversible
• Particles are heavily solvated
• No effect on adding small amount of
electrolyte
• Sol has lower surface tension than the
medium
• Each sol has a viscosity greater than
the medium
• Eg: starch, gelatin, protein etc in water
Lyophobic sol
• Very little affinity between dispersed
phase and dispersion medium
• less stable
• Preparation is difficult
• They are irreversible
• Particles are poorly solvated
• Addition of electrolyte cause
precipitation of dispersed phase
• Sol has a surface tension similar to the
medium
• Each sol has a viscosity comparable to
the medium
• Eg: Gold, Fe(OH)3, As2O3 in water
Colloids, Manju Sebastian, St. Mary's College
6. Classification of colloids
• Macromolecular Colloids- Colloidal
solution of macromolecules like starch,
gelatin, protein etc (lyophilic)
• Multimolecular Colloids- Aggregates of
atoms or molecules in colloidal dimension.
Eg: Au Sol, S sol etc. (lyophobic)
• Associated Colloids- Micelles, above cmc
certain substance shows colloidal property.
Eg: Soaps and detergents (lyophilic)
Colloids, Manju Sebastian, St. Mary's College
7. Preparation of sols
• Preparation of lyophilic sol
– Usually macromolecular colloids are lyophilic
– Easy method of preparation-just warm the
substance to be dispersed in the dispersion
medium
– Eg: Gelatin or starch or soap in warm water,
rubber in benzene
– Intrinsic colloid
Colloids, Manju Sebastian, St. Mary's
College
8. Preparation of lyophobic sol
• 2 methods- Condensation methods and
dispersion methods
Colloids, Manju Sebastian, St. Mary's
College
9. Condensation methods
(Aggregation method)-
– Preparation is through aggregation of molecules
by suitable physical or chemical methods
• Chemical Method-
– Double decomposition As2O3+H2S As2S3+3H2O
– Hydrolysis FeCl3+3H2O Fe(OH)3+3HCl
– Oxidation 2AuCl3 + 3SnCl2 3SnCl4 + Au
– Reduction 2H2S + O2 2H2O+ S
• Physical methods-
– Exchange of solvent- Preparation of aqueous sol of S, P
etc by alcoholic solution
– Change in physical state- Aq. Sol of S or Hg- by passing
their vapours through solution in presence of a stabiliser
Colloids, Manju Sebastian, St. Mary's College
10. Dispersion method
• Large coarse particles are broken down to
smaller ones in colloidal range by dispersion
– Mechanical dispersion
• Using a colloidal mill (2 steel discs having small
clearance between them-rotated in opposite direction in
very high speed)
• Preparation
– Electrodispersion (Bredig’s Arc method)
• Electrical disintegration of coarse material
• Colloidal dispersion of Au, Ag, Pt, Cu etc can prepare
– Peptization
• The process of bringing freshly precipitated substance
into colloidal state by a peptizing agent
Colloids, Manju Sebastian, St. Mary's College
11. Electrodispersion (Bredig’s Arc
method)
• Suitable for aq.
Colloidal dispersions of
metals like Au, Ag etc
• 2 steps
Dispersion step and
condensation step
Colloids, Manju Sebastian, St. Mary's
College
12. Peptization
• Peptizing agent is an electrolyte which
contain ions.
• One of the ion adsorb on a fresh precipitate
which is held together by van der Waal’s
force of attraction
• Eg:
Colloids, Manju Sebastian, St. Mary's College
13. Purification of sols
• 2 methods: Dialysis and ultrafiltration
• Dialysis- Diffusion of impurities through a membrane
• Apparatus used-dialyser (fig)
• If electricity is passed through the solution diffusion
accelerates-Electrodialysis, hot water used in hot dialysis
Colloids, Manju Sebastian, St. Mary's College
14. Ultrafiltration
• Filtration through an ultrafilter
• Remove soluble impurities
• Commonly used ultrafilter-cellophane, pore
sizes are small so that the colloids retained
in the filter while impurities are filtered off
Colloids, Manju Sebastian, St. Mary's
College
15. Properties of sol
• Optical property
– Tyndall effect and ultramicroscope
• Kinetic property
– Brownian motion
• Electrical property
– Electric double layer and zeta potential
Colloids, Manju Sebastian, St. Mary's
College
16. Optical property
Tyndall effect and ultramicroscope
• Sols are heterogeneous, so they shows optical
properties
• Scattering of light by colloidal particles is called
Tyndall effect
• Eg: Cinema projector’s light
Colloids, Manju Sebastian, St. Mary's College
17. • Tyndall effect is used to distinguish
between true solution and colloidal solution
• Most lyophobic sols exhibit tyndall effect.
• Intense tyndall effect is observed when
– The diameter of the dispersed particle is not
much smaller than wavelenth of light used
– There must be a large difference in the
refractive indices of the dispersed phase and
dispersion medium
Colloids, Manju Sebastian, St. Mary's College
18. Application of Tyndall Effect-
Ultramicroscope
• Tyndall beam is viewed through a microscope
• Bright spots of colloidal particle can see
• Determination of sol particles taking advantage of
tyndall effect m/d=4r3n/3
• Radius of the sol particle=(3m/4dn)1/3
Colloids, Manju Sebastian, St. Mary's College
19. Kinetic property- Brownian Motion
• The ceaseless, erratic, zig-zag motion
exhibited by colloidal particles
• Unequal bombardment of colloidal
particles
• Stabilise colloid-counteract the force of
gravity on colloidal particles
• Perrin’s Equation (size of sol by taking
advantage of Brownian motion and
Tyndall effect)
)')((
3
4
ln 12
3
2
1
ddhhgr
n
n
No
RT
Colloids, Manju Sebastian, St. Mary's College
20. Electrical properties
• Colloidal particles are charged
• Charge originate due to preferential
adsorption of ions
• Eg: Fe(OH)3 adsorb Fe3+ ions, As2S3 adsorb
S2-
• Electrical double layer and zeta potential
Colloids, Manju Sebastian, St. Mary's
College
21. Electrical double layer and zeta
potential
• The difference in potential between
the position of closest approach of the
ions to the fixed layer at the surface
and the electroneutral region of bulk
liquid across the diffused layer is
called Zeta potential
• =4ed/D
-is the potential difference
between the hypothetical
plates, D-dielectric con, e-
charge/cm2, d-distance of the
diffused layer
Colloids, Manju Sebastian, St. Mary's
College
22. Consequences of electrical
double layer
• Electrokinetic phenomenon is observed due
to electrical double layer
– Electrophoresis
– Electroosmosis
Colloids, Manju Sebastian, St. Mary's
College
23. Electrophoresis
• When a colloidal particle is placed in an
electric field, the electrically charged
colloidal particles migrate towards the
oppositely charged electrode; this
phenomenon is called electrophoresis
• Type of charge can determine by checking
the migration
• Electrical double layer moves in an electric
field
The pH at which sol particles of an ampholytic substance
become electrically neutral and exhibit no movement in an
electrical field is called isoelectric point of the sol
Colloids, Manju Sebastian, St. Mary's College
24. Electroosmosis
electroendosmosis
• The electrophoretic motion of the dispersed
particles of a sol is prevented by suitable
means, the dispersion medium begins to
move in an electric field; this phenomenon
is called electroosmosis. Sol is taken in middle
compartment
C1, C2 side compartments
D1, D2 dialysing membranes
Colloids, Manju Sebastian, St. Mary's
College
25. Stability of sol
• Lyophobic sol
– Similar charges repel, hence no aggregation
• Lyophilic sol
– Similar charges repel, hence no aggregation
– Extensive solvation
– Brownian motion
Colloids, Manju Sebastian, St. Mary's
College
26. Coagulation of sols
• Coagulation or flocculation is the
precipitation of dispersed phase through
induced aggregation
• Methods
– Persistent electrophoresis
– Persistent dialysis
– Addition of oppositely charged sol
– Addition of electrolytes
Colloids, Manju Sebastian, St. Mary's
College
27. Hardy-Schulze law
• The law states that “The greater the valency
of the ion bearing a charge opposite to that
on sol particles, the greater is its power to
cause coagulation”
• Na+ < Ba2+ < Al3+
• Cl- < SO4
2- < PO4
3- < [Fe(CN)6]4-
Colloids, Manju Sebastian, St. Mary's
College
28. Flocculation value
• The minimum concentration of an
electrolyte required to cause coagulation of
a sol
• Values are in agreement with Hardy
Schulze rule
• NaCl, BaCl2, AlCl3 for As2S3--- 52, 0.69,
0.093
Colloids, Manju Sebastian, St. Mary's
College
29. Protective colloids- Gold number
• A lyophilic substance that offers protection to a lyophobic
sol from the precipitating effect of electrolytes is called
protective colloid
• Eg: gelatin in gold sol
• The protective power of a lyophilic sol is expressed in
terms of gold number
– Gold number of a protective colloid is defined as the weight
in mg of the dry protective colloid that just prevents the
coagulation of 10ml of a standard gold sol on adding 1ml of
10% NaCl solution.
– The smaller the gold no greater the protection
– Gelatin 0.005-0.01, Hb 0.03-0.07, Albumin 0.1-0.2, Starch
20-25 Colloids, Manju Sebastian, St. Mary's
College
30. EMULSIONS
• Dispersed phase and dispersion medium are
liquids
• 2 types
– Oil in water emulsion-oil is the dispersed phase
and water is the dispersion medium , Eg: Milk
– Water in oil emulsions- Water is the dispersed
phase and oil is the dispersion medium, Eg:
Butter
Colloids, Manju Sebastian, St. Mary's
College
31. Tests for determining the type of
emulsion
• Conductance test
– Oil in water > Water in oil
• Dilution test
– Addition of water
• Dye test
– Addition of oil soluble dye (sudan III)
• Spreading test
– Study spreading behaviour on the surface of oil.
Water in oil type spreads quickly
Colloids, Manju Sebastian, St. Mary's
College
32. Preparation and properties of
emulsions
• Emulsification- shaking 2 immisible
components of liquid
• Emulsifier or emulsifiying agents will stabilise
an emulsion by lowering the interfacial tension
between the two liquids and thereby preventing
aggregation.(Eg: soaps and detergents are good
emulsifiers; they emulsify grease with water)
• Demulsification- Breaking up of an emulsion
Colloids, Manju Sebastian, St. Mary's
College
33. Some applications of emulsions
• Milk and water are emulsions of fat in water
are used as constituents of our food.
• Pharmaceutical preparations
• Emulsion of asphalt is used in making roads
• Many superior quality paints are emulsions
• Froth floatation makes use of the process of
emulsification
• Cleansing action of soap/detergent is based on
their emulsifiying properties
Colloids, Manju Sebastian, St. Mary's
College
34. GEL
• Dispersed phase is a liquid and dispersion medium
is a solid
• Eg: Jellies, jam, cheese, silica acid gel etc.
• Structure of gel
– Particles are united through cohesive forces to form an
interlocking system known as fibrils. Fibrils hold the
particle through solvation
• Preparation:
– Cooling- Cooling an aqueous lyophilic sol like gelatin,
starch etc.
– Double decomposition- sodium silicate and HCl on
mixing give silicic acid (silica gel) Colloids, Manju Sebastian, St. Mary's
College
35. Properties of gels
• Elastic and inelastic gels
• Imbibition-The process of imbibing liquid, it may
follow an increase in size of gel is called swelling.
It is shown by elastic gels
• Synerisis- On standing many gel give off small
amount of water and experience a contraction.
• Thixotropy- some Gels on vigorous shaking
changes to sol and back on standing. The
reversible GEL SOL transformation is called
thixotropy Colloids, Manju Sebastian, St. Mary's
College
36. Applications of gels
• Tooth paste, hair gel, boot polishes etc.
• Many food stuffs are in gel form
• Medicines
• Silica gel-remove moisture, desiccant
• Alcohol+calcium acetate gel-in picnic stove
as fuel
• Gelatin, agar agar gels in lab for making
liquid junctionColloids, Manju Sebastian, St. Mary's
College
37. Applications of colloids
• In foods
• In medicine
• In industry
• In sewage disposal
• In laundry
• Formation of deltas
Colloids, Manju Sebastian, St. Mary's
College
38. Sedimentation potential or
Dorn effect
• When the coarse particles of a suspension
are allowed to settle under the influence of
gravity, a potential difference develops
between upper and lower layers of the
liquid column through which they fall. This
phenomenon is known as Dorn effect or
sedimentation potential
• Reverse of electrophoresis
Colloids, Manju Sebastian, St. Mary's
College
40. Significance of Donnan
Equilibrium
• Biological systems – The distribution of
ions between RBC and surrounding plasma
• Artificial kidney
• Tanning of leather
• Dyeing of animal fibres by acid dyes
Colloids, Manju Sebastian, St. Mary's College