Chapter-5 Surface Chemistry

What do you understand by shape selective catalysis? Why are zeolites good
shape selective catalysts?

What is the role of adsorption in froth floatation process used especially for
concentration of sulphide ores?

What are the applications of adsorption in chemical analysis?

What is the role of adsorption in heterogenous catalysis?

Match the items of Column I and Column II.
Column I                                                         Column II
(i) Butter                                                        (a) dispersion of liquid in liquid
(ii) Pumice stone                                              (b) dispersion of solid in liquid
(iii) Milk                                                         (c) dispersion of gas in solid
(iv) Paints                                                       (d) dispersion of liquid in solid

Match the items of Column I and Column II.
Column I                                         Column II
(i) Dialysis                                      (a) Cleansing action of soap
(ii) Peptisation                                (b) Coagulation
(iii) Emulsification                                (c) Colloidal sol formation
(iv) Electrophoresis                           (d) Purification

Match the types of colloidal systems given in Column I with the name given in
Column II.
Column I                                                   Column II
(i) Solid in liquid                                        (a) Foam
(ii) Liquid in solid                                        (b) Sol
(iii) Liquid in liquid                                       (c) Gel
(iv) Gas in liquid                                     (d) Emulsion

Match the statement given in Column I with the phenomenon given in
Column II.
Column I                                                 Column II
(i) Dispersion medium moves in                      (a) Osmosis
an electric field
(ii) Solvent molecules pass through semi         (b) Electrophoresis
permeable membrane towards solvent side
(iii) Movement of charged colloidal particles         (c) Electroosmosis
under the influence of applied electric
potential towards oppositely charged
electrodes
(iv) Solvent molecules pass through sem           i (d) Reverse osmosis
permeable membranes towards
solution side

Method of formation of solution is given in Column I. Match it with the type of
solution given in Column II.
Column I                                               Column II
(i) Sulphur vapours passed                     (a) Normal electrolyte solution
through cold water
(ii) Soap mixed with water above             (b) Molecular colloids
critical micelle concentration
(iii) White of egg whipped with water             (c) Associated colloid
(iv) Soap mixed with water below             (d) Macro molecular colloids
critical micelle concentration  

Do the vital functions of the body such as digestion get affected during fever?
Explain your answer.

How does a solid catalyst enhance the rate of combination of gaseous
molecules?

What is the role of diffusion in heterogenous catalysis?

Why is desorption important for a substance to act as good catalyst?

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

How does a delta form at the meeting place of sea and river water?

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

Why does the white precipitate of silver halide become coloured in the presence
of dye eosin.

What happens when dialysis is prolonged?

What happens when dialysis is prolonged?

Why do physisorption and chemisorption behave differently with rise in
temperature?

Why is Fe(OH)3 colloid positively charged, when prepared by adding FeCl3 to
hot water?

Why does bleeding stop by rubbing moist alum?

On the basis of Hardy-Schulze rule explain why the coagulating power of
phosphate is higher than chloride.

How will you distinguish between dispersed phase and dispersion medium
in an emulsion?

How does the precipitation of colloidal smoke take place in Cottrell precipitator?

Why does leather get hardened after tanning?

Why are some medicines more effective in the colloidal form?

How do emulsifying agents stabilise the emulsion?

A colloid is formed by adding FeCl3 in excess of hot water. What will happen if
excess sodium chloride is added to this colloid?

What causes brownian motion in colloidal dispersion?

What happens when electric field is applied to colloidal solution?

Why do we add alum to purify water?

What is collodion?

Gelatin which is a peptide is added in icecreams. What can be its role?

How does it become possible to cause artificial rain by spraying silver iodide
on the clouds?

What happens when gelatin is mixed with gold sol?

What type of solutions are formed on dissolving different concentrations of
soap in water?

Why is chemisorption referred to as activated adsorption?

What type of solutions are formed on dissolving different concentrations of
soap in water?

Why is chemisorption referred to as activated adsorption?

Why is it important to have clean surface in surface studies?

What are the physical states of dispersed phase and dispersion medium of froth?

What is the cause of Brownian movement among colloidal particles?

Arrange  the  solutions:  True  solution,  colloidal  solution,  suspension  in decreasing order of their particles size?

Give an example of micelles system?

Why is it necessary to remove CO when ammonia is obtained by Haber’s

process?

How is adsorption of a gas related to its critical temperature?

What is meant by Shape Selective Catalyst?

Of the physiorption & chemisorptions, which type of adsorption has higher enthalpy of adsorption?

Write down the Example of Positive Sol?

Write down the Example of Negative Sol? 

Differentiate between physical & chemical adsorption? 

Differentiate between Lyophobic & Lyophilic colloids?

Differentiate  between  multi  molecular,  macromolecular  and  associated

colloids?

What is difference between Sol. & Gel?

Action of Soap is due to Emulsification & Micelle formation? Comment.

Discuss the effect of pressure & temperature on the adsorption of gases on solids?

Describes some features of catalysis by Zeolites?

Comment on the statement that “colloid is not a substance but state of a

substance”?

Write short notes on followings:- (a) Tyndall effect

(b)     Brownian Movement

(c)     Hardy Schulze Rule

Comment on the statement that "colloid is not a substance but a state of substance"

Explain the terms with suitable examples:

(i) Alcosol (ii) Aerosol (iii) Hydrosol

Give four uses of emulsions.

Explain the following terms:

(i) Electrophoresis (ii) Coagulation

(iii) Dialysis (iv) Tyndall effect.

What is shape selective catalysis?

Describe some features of catalysis by zeolites.

What do you mean by activity and selectivity of catalysts?

Give four examples of heterogeneous catalysis.

Action of soap is due to emulsification and micelle formation. Comment.

What is demulsification? Name two demulsifiers.

What are emulsions? What are their different types? Give example of each type.

Explain what is observed

(i) When a beam of light is passed through a colloidal sol.

(ii) An electrolyte, NaCl is added to hydrated ferric oxide sol.

(iii) Electric current is passed through a colloidal sol?

How are colloids classified on the basis of

(i) Physical states of components

(ii) Nature of dispersion medium and

(iii) Interaction between dispersed phase and dispersion medium?

What are enzymes? Write in brief the mechanism of enzyme catalysis.

What is the difference between multimolecular and macromolecular colloids? Give one example of each. How are associated colloids different from these two types of colloids?

What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?

Discuss the effect of pressure and temperature on the adsorption of gases on solids.

How are the colloidal solutions classified on the basis of physical states of the dispersed phase and dispersion medium?

Why is adsorption always exothermic?

What role does adsorption play in heterogeneous catalysis?

What do you understand by activation of adsorbent? How is it achieved?

What is an adsorption isotherm? Describe Freundlich adsorption isotherm.

What are the factors which influence the adsorption of a gas on a solid?

Give reason why a finely divided substance is more effective as an adsorbent.

What is the difference between physisorption and chemisorption?

Distinguish between the meaning of the terms adsorption and absorption.

Give one example of each.

Why is it essential to wash the precipitate with water before estimating it quantitatively?

What modification can you suggest in the Hardy-Schulze law?

What is the role of desorption in the process of catalysis?

Why is the ester hydrolysis slow in the beginning and becomes faster after sometime?

Why is it necessary to remove CO when ammonia is obtained by Haber's process?

Why are powdered substances more effective adsorbents than their crystalline forms?

Why does physisorption decrease with the increase of temperature?

Write any two characteristics of Chemisorption.