Explore topic-wise InterviewSolutions in .

1. Interface: The surface of separation of the two phases where the concentration of adsorbed molecule is high is known as interface.

2. Desorption: The process of removing an adsorbed substance from the substance is called desorption.

Removal of adsorbate from the surface of adsorbent is known as desorption. 

The extent of surface adsorption does not depend on Density

AS₂S₃ has spherical shape

(d) rod like

(a) (i) & (iii)

1. The gaseshaving low critical temperature are adsorbed slowly, while gases with high critical temperature are adborbed readily.

2. Among CO₂ , and NH₃ , NH₃ will be more readily adsorbed on the surface of the charcoal. This is because the critical temperature of ammonia gas is quite high than the CO₂ . Hence, it easily combines with the materials than the CO₂ whether it is solid, liquid or any gases.

Due to high critical temperature and easily liquefiable gas NH₃ is more readily adsorbed on the surface of charcoal.

 The catalytic reaction that depends upon the structure of the catalyst and size of the reactant and product molecules is called shape selective catalyst. e.g. Zeolite.

The catalytic reaction that depends upon the pore size e of the catalyst and also the size of reactant and product molecules is called shape selective catalysis. 

e.g. Zeolites are good shape selective catalyst.

Lyophilic colloids: Gum and Starch
Lyphobic colloids: As₂S₃ and Au sol.

(ii) ΔH = TΔS

(a) (iv) (i) (ii) (iii)

(b) Both A and R are correct and R is the correct explanation of A.

(a) Hydrolysis of sucrose in presence of all HCl 

Both reactant and catalyst are in same phase. i.e. (1)

(c) temperature

(a) Nitrocellulose

pyroxylin (nitro cellulose)

1. active centres 

2. easily liquefiable 

3. Permanent, adsorbed 

4. Adsorption isotherm 

5. gases on solid surface 

6. charcoal 

7. Activated charcoal 

8. silica gel

9. alumina, silica

10. Permutit

(d) A < C < B < D

1. interface 

2. positive adsorption 

3. desorption 

4. free energy 

5. occlusion 

6. sorption 

7. 400kJ/rnole

8. Van der Waals forces of attraction 9. low temperature 

10. Chemisorption

(d) activated charcoal

(a) Both A and R are correct and R is the correct explanation of A.

I. By heating

II. By chemical – Smelting, Aluminothermite process.

III. Auto reduction

OR

IV.  Electrolytic reduction

(ii) Assertion and reason both are correct but reason does not explain assertion.

The answer is (a) Gelatin

Chromatographic method.

(b) 1 mμ to 1 μm diameter

1. The pores of ordinary filter papers permit the passage of colloidal solutions. In ultrafilteration, the membranes are made by using collodion, cellophane or visiking.

2. Vhen a colloidal solution is filtered using such a filter, colloidal particles are separated on the filter and the impurities are removed as washings.

3. This process is quickened by application of pressure. The separation of sol particles from electrolyte by fikration through an ultrafilter is called ultrafiltration. 

4. Collodian is 4% solution of nitrocellulose in a mixmre of alcohol and water.

Adsorption is a surface phenomenon. Therefore, adsorption is directly proportional to the surface area. A finely divided substance has a large surface area. Both physisorption and chemisorption increase with an increase in the surface area. Hence, a finely divided substances behaves as a good absorbent.

The gold number is defined as the number of milligrams of a hydrophilic colloid that will just prevent the precipitation of 10 mL of a gold sol on the addition of 1 mL 10% NaCl solution.

Nonmetals are extracted by oxidation method.

Metal should form volatile compound with given reagent at low temperature. Volatile compound of metal should be unstable at high temperature. 

Saponification value of soaps depends on the amount of base required to saponify therefore soaps do not show saponification in acidic medium.

Zeolite catalyst ZSM-5 is used for converting methanol into gasoline.

Adsorption is a surface phenomenon. The extent of adsorption depends on the surface area, therefore adsorption is directly proportional to surface area. A finely divided substance like nickel, platinum and porous substances like charcoal, silica gel provide large surface area. Hence, finely divided substances behave as good adsorbent.

1. Oil-in-water (O/W): milk

2. Water in oil (W/O): Butter

(c) micoderma

Urease is used in the hydrolysis of urea

(d) Gold sol

An example of liquid aerosol is Fog

(a) mayonnaise

(a) The gas masks function on principle of adsorption. 

(b) Chromatography is based on adsorption phenomenon.

1. A negative ion causes the precipitation of positively changed sol and vice versa.

2. When the valency of ion is high, the precipitation power increased. So in cations the precipitation power order is Al³⁺ > Ba²⁺ > Na and in anions the precipitation power order is [Fe(CN)₆]^4- > SO₄^2- > Cl^-.

3. The precipitation power of electrolyte is determined by finding the minimum concentration required to cause precipitation of sol in 2hrs. This value is called flocculation value. The smaller the flocculation value, greater will be precipitation.

(1) In the preparation of gas masks using activated charcoal to avoid poisonous gases like CO, CH₄ etc.     

(2) Froth floatation method used for concentration of sulphide ores is based on adsorption. 

(3) Silica gel can be used to remove moisture and to control humidity.     

(4) Ion exchange method used to soften water is based on adsorption.     

(5) Adsorption chromatography is used to purify and separate pigments, harmones etc.     

(6) Charcoal powder can remove coloured impurities from sugar.     

(7) Charcoal is used for making high vacuum.     

(8) The cleaning action of soaps and detergents.     

(9) Formation of stable emulsions in cosmetics and syrups etc.     

(10) In heterogeneous catalysis.

(i) Assertion and reason both are correct and the reason is correct explanation of assertion.

Role of adsorption in a catalytic reaction. The role of heterogeneous catalysis has been explained on the basis of adsorption theory postulated by Faraday. 

According to it: Due to unsatisfied valences forces on the catalyst surface, the molecules of the gaseous reactants get adsorbed in unimolecular layer.Due to increased concentration of the reacting substances on the surface of the solid catalyst the chemical action is accelerated. 

The electrical charges of the particles prevent them from coming together due to electrostatic repulsion. All the dispersed particles in a colloidal solution carry the same charge while the dispersion medium has equal and opposite charge.

(c) Electro osmosis