Adsorption isotherm for solutions. The variation of extent of adsorption (x/m) and the equilibrium concentration (c) is expressed as
\(\frac { x }{ m } ={ kc }^{ 1/n }\) --------(i)
where k and n are constants which depend on the nature of adsorbent, adsorbate, and temperature. A graph between x/m and has been found to be similar to one shown for x/m and for gasses on solids. Taking logarithms, Eq. (i) becomes
\(log\frac { x }{ m } =k+\frac { 1 }{ n } log\quad c\)
when a graph is plotted between x/m and log c, a  graph similar to has been obtained. From this 1/n graph, the value of 1/n and log k can be obtained as n slope and intercept respectively.

(i) Chromatography is based on differential absorption.
(ii) The charge on the colloidal solution is due to selective adsorption of common ions on the surface.
(iii) Heterogeneous catalysis is based, on adsorption of gasses on solid.
(iv) Carbon particles from smoke get adsorbed on the surface of electrodes of Cottrell smoke precipitator

(i) Alcosol: Is is a colloidal dispersion having alcohol as the dispersion medium, e.g., collodion (a colloidal sol of cellulose nitrate in ethyl alcohol).
(ii) Aerosol: It is a colloidal dispersion of a liquid in a gas, e.g., fog.
(iii) Hydrosol: It is a colloidal sol of a solid in water as the dispersion medium, e.g., starch sol or gold sol.

Platinium and palladium form inert electrodes,i.e., they are not attacked by the ions of the electrolyte or the products of electrolysis. Hence, they are used as electrodes for carrying out the electrolysis.

Coagulation of Fe(OH)₃ sol takes place because excess of Cl^- will react with Fe(OH)_3. Fe(OH)₃ is multimolecular colloid.

\(\underset { Propene }{ { CH }_{ 2 }=CH-{ CH }_{ 3 }+{ O }_{ 2 } } \xrightarrow{BiMoO_4}\underset { Acrolein }{ { CH }_{ 2 }=CH-{ CH }O } +H_2O\)
This reaction explains selectivity of the catalyst

(a) Emulsification: The process of making an emulsion from an oil is termed emulsification.
(b) Emulsifying agent: The substances which stabilise emulsions are called emulsifying agents or emulsifier, e.g. soaps and detergents.
(c) Demulsifier: It is a substance which changes the emulsion into two separate layers.

Zeolites are being widely used as catalyst in petrochemical industries for cracking of hydrocarbons and isomerisation.An important catalyst used in the petroleum industry is ZSM-S.It converts alcohols directly into gasoline (petrol) by dehydrating them so that a mixture of hydrocarbon is obtained. Since zeolites have specific pore size therefore, only alcohols of specific size and shape are catalysed by them and converted into hydrocarbons.

Sulfur sol can be prepared by oxidation of with the help\({ H }_{ 2 }S\) of Conc. \({ HNO }_{ 3 }\)
\({ H }_{ 2 }S\overset { [O] }{ \underset { { HNO }_{ 3 } }{ \rightarrow } } { H }_{ 2 }O+S\ \ { HNO }_{ 3 }\)
Bredig's Arc Method: Platinum (Pt) sol can be prepared by Bredig's arc method. Two Pt metal electrodes are taken through which high voltage is passed so that metal gets vaporized. When vapors are condensed, a colloidal solution of Pt in water is obtained.

In butter, dispersed phase-liquid; dispersion medium- solid.

Sol is solid dispersed in liquid, e.g. paints, cell fluids etc.

Cationic detergents are quarternary ammonium salts of amines with acetates, chlorides or bromides as anions. The cationic part possesses a long hydrocarbon chain with a positive charge on nitrogen atom. e.g. cetyltrimethylammonium bromide used in hair conditioners.
\(\left[ { CH }_{ 3 }({ CH }_{ 2 })_{ 15 }-\overset { \begin{matrix} { CH }_{ 3 } \\ | \end{matrix} }{ \underset { \begin{matrix} | \\ { CH }_{ 3 } \end{matrix} }{ N } } \right] ^{ + }{ Br }^{ - }\)
(ii) Broad spectrum antibiotic Antibiotics which kill or inhibit a wide range of harmful or disease causing bacteria are called broad spectrum antibiotics. These are equally effective against gram-positive and gram-negative bacteria (both). e.g. ampicillin and amoxycillin.
(iii) Tranquiliser The chemical compounds which are used for the treatment of stress, mild and severe mental diseases are known as tranqulisers,
e.g. equanil. They form an essential component of sleeping pills

(i) Smaller the size of the particles of adsorbent larger will be the surface area and greater will be the extent of adsorption.
(ii) At constant temperature, the extent of adsorption increases with increase of pressure, rapidly in the beginning, relatively slow at moderate pressure and ultimately becomes independent of pressure.
(iii) At constant pressure, the physical adsorption decreases with increase of temperature whereas, the chemisorption first increases and then decreases.

(a) silver sol. in water is prepared by striking electric arc between two silver rods suspended in alkaline water. (Bredig's are method)
(ii) 2H₂S+H₂SO₃ \(\rightarrow\) 3H₂O+3S
(iii) Fecl₃+3H₂O \(\rightarrow\) Fe(OH)₃+3HCL
(iv) 2AuCl₃+3SnCl₂ \(\rightarrow\) 2Au+3SnCl₄
(b) (i) The gas masks function on principle of adsorption.
(ii) Chromatography is based on adsorption phenomenon.

Two types of emulsions are as follows:

Application of Emulsions:
(i) In medicine: The various pharmaceuticals and cosmetics are available in liquid form such as codliver oil etc., and some creams and ointment are emulsions of water in oil type.
(ii) Cleaning action of soap: This action is based on the formation of oil in water type emulsions

In heterogeneous catalysis, generally, the reactants are gaseous whereas catalysts a solid. The reactant molecules are adsorbed on the surface of the solid catalyst by physical adsorption or chemisorption. As a result of the concentration of the reactant molecules on the surface increases and hence the rate of reaction increases. Alternatively, one of the reactant molecules undergoes fragmentation on the surface of the solid catalyst producing active species which react faster. The product molecules, in either case, have no affinity for the solid catalyst and are desorbed making the surface free for fresh adsorption. This theory is called adsorption theory.

a) Silica gel is a good adsorbent and hence water vapour are adsorbed on its surface. Anhydrous CaCl₂ undergoes absorption because it combines with water molecules to form hydrated calcium chloride, CaCI₂. 2H₂O.
b) BF₃ acts as a strong Lewis acid and hence used as catalyst in industrial processes.

When we plot a graph between the extent of adsorption (x/m) vs pressure (p) at a constant temperature, it is called adsorption isotherm.Freundlich adsorption isotherm fails at high pressure of gas, whereas Langmuir adsorption isotherm does not. Langmuir adsorption isotherm is based on kinetic. theory of gasses. It involves two processes, i.e. adsorption and desorption. It is applicable to chemical adsorption in which unimolecular layer is formed. Langmuir adsorption isotherm is based on assumption that every adsorption site is equivalent and that the ability of a particle to bind a particular at adsorption site or active site does not depend on whether or not nearby sites are occupied

(iii) When solid is dispersed in water, it is called hydrosol, e.g. starch dispersed in water.

Colloidal particles are big in size (macromolecular) and hence small in number in the same amount in grams/litre.

(i) Soaps work due to the formation of micelles. But the formation of micelles takes place at a minimum temperature called 'Kraft temperature'. This temperature is reached in luke warm water.
(ii) Be humble to accept a scientific fact from a elder person.

(i) Finely divided nickel is used as catalyst in hydrogenation.
(ii) No, we should use vegetable oil instead of vegetable ghee as it is partly saturated, may lead to formation of cholesterol.
(iii) Nickel gets mixed with vegetable ghee. It is harmful for our body as it is found to be carcinogenic (cancer causing).
(iv) It is because these led to the formation of excess of acid, which leads to hyperacidity, indigestion and stomach disorders.
(v) These are basic in nature and thus can induce more secretion of hydrochloric acid in gastric juice, that is why, these should be avoided as far as possible.

(i) Blood is a colloidal solution of albuminoid substance. The styptic action (blood stopping action) of alum is due to coagulation of blood forming a clot which stops further bleeding.
(ii) Values associated with Meera's decision are:
(a) Friendship
(b) Keen observation
(c) Applying knowledge of chemistry to daily life
(d) Responsibility
(e) Love and care.

Method of preparation. An emulsion is prepared by shaking strongly the mixture of the two liquids or by passing the mixture through a colloid mill, called the homogenizer. The emulsions thus prepared from the pure liquids are usually not stable and the two liquids separate out on standing. To get a stable emulsion, small quantities of certain other substances are added during preparation. The substances thus added (tJ stabilize the emulsions are called emulsifiers or emulsifying agents. The substances commonly used as emulsifying agents are soaps of various kinds, long chain sulphonic acids or lyophilic colloids (proteins, gum, agar etc.).
Role of emulsifier. The role of emulsifier can be explained taking the example of soap as an emulsifier. Soaps are sodium or potassium salts of higher fatty acids, e.g., sodium palmitate (C15H31COONa), sodium stearate (C₁₇H₃₅COONa), etc. A molecule of soap consists of two parts, the hydrocarbon part (C₁₅H₃₁ -, C₁₇H₃₅ - , etc.) which is soluble in oil and the polar group (COO-Na+) which is soluble in water
         R                           COO-Na+
Hydrophobic part         Hydrophilic part
(Soluble in oil)            (Soluble in water)
Thus, if a drop of oil is surrounded by soap solution, the R - part of the soap remains in the oil and the COO^-Na⁺ part remains in water as shown in Fig. 5.31. Thus, soap molecules are concentrated over the surface of the drop of oil. As a result, the interracial tension between oil and water decreases and hence they are intermixed into each other to form the emulsion.Thus, micelles are formed Some other commonly used stabilizing agents are proteins, gums and agar
Types of Emulsions. If the term "oil" is used for any liquid which is immicible with water and is capable of forming an emulsion with water, then the various types of emulsions may be classified into two types (fig. 5.32). These are:
(i) Emulsion of oil-in-water (o/w) in which oil is the dispersed phase and water is the dispersion medium.
For example, milk is an emulsion of liquid fat dispersed
in water. Another well known example is that of vanishing cream
(ii)Emulsion of water-in-oil (w/o) in which water is the dispersed phase and oil is the dispersion medium.For example, cod liver oil is an emusion of water in oil, i.e., water is the dispersed phase and oil is the dispersion medium. Two other common examples of this type are butter and cold cream.
Evidently, the type of emulsion depends upon the relative amounts of the two liquids. If water is in excess, it is oil-in-water emulsion.JIf oil is in excess, it is water-in-oil emulsion. The type of emulsion formed also depends upon the nature of the emulsifying agent. For example, the presence of soluble soaps as the emulsifying agents generally favours the formation of emulsions of oil-in-water whereas the presence of insoluble soaps (containing non-alkali metal atoms) favours the formation of emulsions of water-in-oil.Some very commonly used emulsifying agents for o/w emulsions are : proteins, gums, natural and synthetic soaps whereas for w/o emulsions are: heavy metal salts of fatty acids, long chain alcohols, lamp black, etc
To test the type of emulsion. The type to which the given emulsion belongs can be tested experimentally by anyone of the following methods:
(i) Microscopic method. To a small amount of the given emulsion, a few drops of water are added. The water will mix completely if the emulsion is oil-in-water type. Likewise, for the water-in-oil emulsion, the miscibility with a few drops of oil can be tested. The miscibility can be seen under a microscope. 
(ii) Conductance method. This method is based upon adding a small amount of an electrolyte to the emulsion. If the conductance increases, the emulsion is oil-in-water type and if there is no significant change, it is water-in-oil type.
(iii) Dye method. A small amount of an oil-soluble dye is added to the emulsion. If it is water-in-oil type, it becomes deeply coloured, otherwise it remains colourless.

At P = 0.5 atm, \(\frac { x }{ m } kP1/n\ =\ 2\times { (0.5) }^{ 1 }=1.0\)

V₂ = 59.6 cm³