(a) What happens when a freshly precipitated Fe(OH)₃ is shaken with water containing a small quantity of FeCl₃?
(b) Why is finely divided substance more effective as an adsorbent?

2

(a)

What is the sign of \(\Delta H\) and  \(\Delta S\) when bromine gas gets adsorbed on charcoal?

2

(a)

What happens when a solution of NaCl is added to Fe(OH)₃ sol, explain? Write whether Fe(OH)₃ sol is a multimolecular colloid or macromolecular colloid.

2

(a)

Why are substances like platinum and palladium often used for carrying out electrolysis of aqueous solutions?

2

(a)

What role does adsorption play in hetrogeneous catalysis?

2

(a)

Explain the terms with suitable examples:
(i) Alcosol
(ii) Aerosol and
(iii) Hydrosol 

2

(a)

What is the role of activated charcoal in gas mask used in coal mines?

2

(a)

Give an example where physisorption changes to chemisorption with rise in temperature. Explain the reason for the change.

2

(a)

Describe the preparation of the following colloidal solutions. Name the method used in each case.

(i) Silver sol

(ii) Sulphur sol

(iii) Collodion

(iv) Gold sol.

2

(a)

(a) Heat of adsorption is greater for chemisorption than physiorption. Why?
(b) What is collodion?
(c) Differentiate between peptization and coagulation.

2

(a)

(a) In reference to Freundlich adsorption isotherm, write the expression for absorption of gases on solids in the form of an equation.

2

(a)

Explain the following methods for preparing colloids:

(i) Bredig's arc method.

(ii) Peptisation.

2

(a)

Giving appropriate examples, explain how the two types of processes of adsorption (physisorption and chemisorption) are influenced by the prevailing temperature, the surface area of adsorbent and the activation energy of the process?

2

(a)

Explain the following terms by giving one example for each.
(i) Micelles
(ii) Aerosol

2

(a)

Explain the curdling of milk when it is sour.

2

(a)