NCERT Solutions for Class 12 Chemistry Chapter 5 – Surface Chemistry

NCERT Solutions for Class 12 Chemistry Chapter 5 – Surface Chemistry cover all the topics given in chapter 5. This chapter presents the interfacial phenomenon and its significance in chemistry. This chapter of NCERT Solutions tells you about adsorption, its types and its mechanism. Further, it explains the factors controlling adsorption on solids and Freundlich’s adsorption isotherm. This chapter also talks about the role of catalysts in industry and colloidal solutions, their preparation methods and properties and use of colloids.

In this chapter, there are a total of 27 questions asked at the end. All of these questions have been answered on the basis of guidelines given by CBSE and NCERT. These are designed to cover all the concepts taught in NCERT CBSE Class 12 Chemistry Chapter 5 in details and in a step by step manner. The direct and applicative questions of the exercise are based on adsorption and its types, properties and factors affecting adsorption, colloidal solutions and its properties, emulsions and micelles. 

All of these questions have been answered precisely in Class 12 Chemistry Chapter 5 – Surface Chemistry. The solutions are framed in such a way that they make learning fun, interesting, engaging, interactive and an efficient process.

NCERT Class 12 Chemistry Chapter 5

NCERT Solutions for Class 12 Chemistry Chapter 5 – Surface Chemistry includes all the concepts of this chapter. They give you a comprehensive understanding of the chapter. The main points given in this chapter are as follows –

  • Adsorption

This chapter introduces you to the adsorption which is a phenomenon of attracting and retaining the molecules of a substance (gaseous or liquid) on the surface, resulting in a higher surface concentration compared to bulk. The material adsorbed is known as adsorbate, and one which adsorbs is called adsorbent.

  • Types of adsorption

This part of the chapter tells you about physisorption which occurs due to weak van der Waals forces between adsorbate and adsorbent surface and chemisorption which is a result of strong chemical bond formation between the molecules of adsorbate and adsorbent.  

  • Adsorption isotherms

This part of the NCERT CBSE Class 12 Chemistry Chapter 4 teaches you that adsorption isotherm is a curve which expresses the variation in the amount of gas adsorbed by the adsorbent with variation in pressure at a constant temperature. According to Freundlich’s adsorption isotherm x/m = k.p1/n (n >1), where x is the mass of the gas adsorbed on mass m of the adsorbent at pressure p. The validity of Freundlich’s isotherm is obtained by plotting x/m on x and log p on y axis to obtain a straight line.

This portion further tells that solids absorb solutes from solution phase also where it has been observed that extent of adsorption – decreases with increase in temperature and increases with the increase of surface area and depends on the concentration of solute in solution and nature of adsorbate and adsorbent used.

CBSE NCERT Class 12 Chemistry Chapter 5 further tells you regarding the application of adsorption phenomenon in various areas like metallurgy, chromatographic separations, industrial productions etc.

  • Catalysis

This part of the chapter tells you that catalysis helps us by increasing the rate of chemical reactions widespread in many industries.

  • Homogeneous and heterogeneous catalysis

This part of the chapter tells us that in homogeneous catalysis, the catalyst is in the same phase as of reactants and heterogeneous catalysis is the case where catalyst and reactants are in different phases.

  • Adsorption theory of heterogeneous catalysis

This part of the NCERT Class 12 Chemistry Chapter 5 makes you aware of the old and modern theories explaining the mechanism of heterogeneous catalysis.

This further tells you that according to modern adsorption theory the mechanism has the following steps – diffusion of reactants to the surface of catalyst followed by adsorption of reactants and occurrence of chemical reaction on the catalyst surface and finally desorption of products from the catalytic surface and their moving away. Catalysts find a large utility in various industries.

  • Enzyme catalysis 

This part of the Class 12 Surface Chemistry chapter mentions that enzymes are complex organic compounds containing nitrogen elements and produced by plants and animals. These are protein molecules catalyzing biochemical reactions. Enzyme catalysis is unique in being highly specific and efficient. 

  • Colloids

This part of the chapter teaches you about colloid, which is a heterogeneous system with particles of finely dispersed substance (dispersed phase) in another substance known as the dispersion medium. Colloidal solutions are midway between true solutions and suspensions.

  • Classification of colloids

This part of the chapter tells you that colloids are divided based on the criterion such as the physical state of the mediums, nature of the interaction between the mediums and type of particles of the dispersed phase. The most common types are sols (solids in liquids), gels (liquids in solids) and emulsions (liquids in liquids).

  • Preparation of colloids

This part of the chapter tells you that colloidal solutions can be prepared by chemical, electrical and peptization methods. 

  • Purification of colloidal solutions

This part of the NCERT CLas 12 Chemistry Chapter 5 teaches you that dialysis, electrodialysis and ultrafiltration are the methods of removing impurities from colloidal solutions.

  • Properties of colloidal solutions

Here you come to know that colloidal solutions show various properties due to the presence of particles in them. Colligative properties, Tyndall effect, Brownian movement, the charge on particles, the colour of colloidal solution, electrophoresis and coagulation are the common properties shown by them.

  • Emulsions

This portion of the chapter teaches you that emulsions are colloidal systems in which both dispersed phase and dispersion medium are liquids and can be of either water in oil type or oil in water type. The process of preparing emulsion is known as emulsification, and an emulsifier is added to ensure the stability of an emulsion. 

  • Colloids Around Us

This portion gives you examples of colloids observed in daily life and application of colloids in industry. 

CBSE NCERT Class 12 Chemistry Chapter 5 Exercise

Our NCERT Solutions for Chapter 5 – Surface Chemistry consists of 27 questions covering the important topics learnt here. The constituents of the exercise have been listed below.

  • Question 1 is a differential question asking you to distinguish between adsorption and absorption.
  • Question 2 is a differential question on types of adsorption.
  • Question 3 is an application-based question.
  • Question 4 is a direct question based on factors affecting adsorption. 
  • Question 5 is a direct question on adsorption isotherm.
  • Question 6 asks about the activation of an adsorbent.
  • Question 7 asks you to comment upon the role of adsorption in heterogeneous catalysis and 19 asks to provide examples of heterogeneous catalysis.
  • Question 8 asks you why adsorption releases heat.
  • Questions 9, 11, 12, 14, 26 and 27 are based on colloids. 
  • Question 10 is based on factors affecting adsorption. 
  • Question 13 is a direct question based on enzymes.
  • Questions 15 and 23 are based on various properties of colloidal solutions. 
  • Questions 16 to 18 and 24 are based on emulsions.
  • Question 20 is a comparative question on activity and selectivity of catalysis. 
  • Question 21 asks you to describe the features of zeolite catalysis.
  • Question 22 is a direct question on shape-selective catalysis.
  • Question 25 is a direct question based on micelles.
  • Question 26 asks you to explain the given terms on sols.

There are 8 intext questions asked in CBSE NCERT Class 12 Chemistry Chapter 5 to which suitable answers are provided in our solutions.

Benefits of NCERT Solutions for Class 12th Chemistry Chapter 5 – Surface Chemistry 

Some of the major benefits of learning and revising from NCERT Solutions for Class 12 Chemistry Chapter 5 – Surface Chemistry are as follows –

  • These are user friendly, and you can learn from them anywhere anytime.
  • They are less time and effort consuming.
  • They help you build a strong conceptual foundation. 
  • They include detail explanations and relevant examples to help you learn efficiently.
  • They cover a wide range of question types important from exam point of view.

They help you score well in your class 12th board exams.