NCERT Solutions for Class 12 Chemistry Chemistry Part-1 Chapter 5

Surface Chemistry Class 12

Chapter 5 Surface Chemistry Exercise Solutions

<< Previous Chapter 4 : Chemical Kinetics Next Chapter 6 : General Principles and Processes of Isolation of Elements >>

In text : Solutions of Questions on Page Number : 127

Q1 :  

Write any two characteristics of Chemisorption.


Answer :

1. Chemisorption is highly specific in nature. It occurs only if there is a possibility of chemical bonding between the adsorbent and the adsorbate.

2. Like physisorption, chemisorption also increases with an increase in the surface area of the adsorbent.

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Q2 :  

Why does physisorption decrease with the increase of temperature?


Answer :

Physisorption is exothermic in nature. Therefore, in accordance with Le-Chateliere's principle, it decreases with an increase in temperature. This means that physisorption occurs more readily at a lower temperature.

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Q3 :  

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


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Q4 :  

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


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Q5 :  

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


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Q6 :  

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


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Q7 :  

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


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Q8 :  

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


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<< Previous Chapter 4 : Chemical Kinetics Next Chapter 6 : General Principles and Processes of Isolation of Elements >>

Exercise : Solutions of Questions on Page Number : 146

Q1 :  

Distinguish between the meaning of the terms adsorption and absorption.

Give one example of each.


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Q2 :  

What is the difference between physisorption and chemisorption?


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Q3 :  

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


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Q4 :  

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


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Q5 :  

What is an adsorption isotherm? Describe Freundlich adsorption isotherm.


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Q6 :  

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


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Q7 :  

What role does adsorption play in heterogeneous catalysis?


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Q8 :  

Why is adsorption always exothermic?


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Q9 :  

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


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Q10 :  

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


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Q11 :  

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


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Q12 :  

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?


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Q13 :  

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


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Q14 :  

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?


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Q15 :  

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?


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Q16 :  

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


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Q17 :  

What is demulsification? Name two demulsifiers.


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Q18 :  

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


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Q19 :  

Give four examples of heterogeneous catalysis.


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Q20 :  

What do you mean by activity and selectivity of catalysts?


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Q21 :  

Describe some features of catalysis by zeolites.


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Q22 :  

What is shape selective catalysis?


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Q23 :  

Explain the following terms:

(i) Electrophoresis (ii) Coagulation

(iii) Dialysis (iv) Tyndall effect.


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Q24 :  

Give four uses of emulsions.


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Q25 :  

Give four uses of emulsions.


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Q26 :  

Explain the terms with suitable examples:

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


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Q27 :  

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


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<< Previous Chapter 4 : Chemical Kinetics Next Chapter 6 : General Principles and Processes of Isolation of Elements >>

Chemistry Part-1 - Chemistry : CBSE NCERT Exercise Solutions for Class 12th for Surface Chemistry will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.

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