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NCERT Solutions for Class 12 Chemistry Chemistry I Chapter 5 Surface Chemistry

NCERT Solution For Class 12 Chemistry Chemistry I

Surface Chemistry Here is the CBSE Chemistry Chapter 5 for Class 12 students. Summary and detailed explanation of the lesson, including the definitions of difficult words. All of the exercises and questions and answers from the lesson's back end have been completed. NCERT Solutions for Class 12 Chemistry Surface Chemistry Chapter 5 NCERT Solutions for Class 12 Chemistry Surface Chemistry Chapter 5 The following is a summary in Hindi and English for the academic year 2024-25. You can save these solutions to your computer or use the Class 12 Chemistry.

Question 1

NCERT Solutions for Class 12 Chemistry Chemistry I Chapter 5 Surface Chemistry

NCERT Solution For Class 12 Chemistry Chemistry I

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

Why does physisorption decrease with the increase of temperature?

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

In Haber's process, hydrogen is obtained by reacting methane with steam in presence of NiO as catalyst. The process is known as steam reforming. Why is it necessary to remove CO when ammonia is obtained by Haber’s process?

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

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

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

What is adsorption?

What do you mean by adsorbent and adsorbate?

What is desorption?

Define physical and chemical adsorption.

Is adsorption exothermic or endothermic?

What is an adsorption isotherm and isobar?

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

Name a few common adsorbents.

What property must a good adsorbent have?

Why colloids are regarded as very good adsorbents?

What do you mean by sorption?

How do the surface molecules have the tendency of adsorption?

What are homogeneous and heterogeneous catalysts?

What are Zeolites?

Write the Freundlich adsorption isotherm for the adsorption from solution.

Give the Langmuir adsorption isotherm expression for the adsorption from solutions.

Why catalyst are required in very small non-stoichiometric quantities?

What are enzymes?

Name some solid catalysts.

What is meant by the term ‘peptization’?

How does BF3 act as a catalyst in industrial process?

What happens when an electric field is applied to a colloidal dispersion?

Give an example of an associated colloid.

Mention an application of emulsions.

How can the Freundlich adsorption isotherm be represented when the value of n is less than one?

Why is a catalyst, in general in the form of finely divided powder?

How does the emulsification of fats take place in the intestines?

Which colloidal system is represented by butter?

Why do colloidal solution exhibit Tyndall effect?

State any one characteristic of enzymatic catalysis.

What is the cause of Brownian movement observed in colloidal solutions?

What is the sign of ΔH and ΔS when bromine gas gets absorbed on charcoal?

Why is a lyophilic colloid more stable than a lyophobic colloid?

What is an aerosol?

What is a gel? Give one example?

What do you mean by the selectivity of the catalyst?

Deltas are formed where the river and sea water meet. Give reasons.

What is the effect of increase of temperature on the adsorption of a gas on a solid surface?

Write the name of the states of (i) dispersed phase and, (ii) dispersion medium in the case of butter.

Write a mathematical expression showing relationship between the amount of solute adsorbed per unit mass of the solid adsorbent and the concentration of the solute in solution.

What do x and m represent in the following expression:xm=kP1/n?

What are emulsifiers?

What happens when a freshly precipitated Fe(OH)3 is shaken with little amount of dilute solution of FeCl3?

Which will adsorbe more a lump of charcoal or charcoal powder, and why?

Draw a plot of variation in the quantity of the gas absorbed (x/m) with the pressure of the gas?

What is observed when sodium chloride is added to ferric hydroxide sol?

Give one difference between sol and gel.

What are macro-molecular colloids? Give one example.

Derive the variation of x/m versus temperature for physical adsorption process. Explain the nature of the curve.

What is common in aqua-sols and solid aerosols? Also find the point of distinction between them.

What is electrophoresis due to?

Give one example each of positively charged sol and one example of negatively charged sol:

How does chemical adsorption of a gas on a solid vary with temperature?

What is meant by ‘Shape selective’ catalysis?

Define the enthalpy of adsorption.

Write down the heterogeneous catalyst involved in the polymerisation of ethylene.

Of NH3 and N2 which gas will be absorbed more readily on the surface of charcoal and why?

What is the range for the enthalpy of adsorption for physisorption and chemisorption?

Lyophilic sols are reversible whereas lyophobic sols are irreversible. Why?

Why does chemisorption have more heat of adsorption than physico-adsorption?

Colloidal solution can be had in a water and in air as media. What distinctive names are given to these two types of sols?

Which sol is more stable-lyophilic or lyophobic?

Write one example of each category in which sols particles carry – ve and + ve charges.

Give one example each of W / O and O / W emulsion.

Which names are given if sols have dispersion medium of (a) H2O, (b) alcohol, (c) benzene?

Write the order of effectiveness of the equimolar solutions of following electrolytes for coagulating a negatively charged sol.FeCl3, NaCl, BaCI2, Th(NO3)4.

Why are lyophilic sols self-stabilized?

A sol is prepared by addition of excess of AgNO3 solution in KI solution. What charge is likely to develop on the colloidal particles?

How can a colloidal solution and true solution of the same colour be distinguished from each other?

Write the reaction in which bismuth molybdate is used as a catalyst.

What is the difference in the nature of a dilute soap solution and a concentrated soap solution?

How does BF₃ act as a catalyst in industrial process?

What do x and m represent in the following expression:
$(\frac{x}{m}) = {kP}^{1 / n} ?$

What happens when a freshly precipitated Fe(OH)₃ is shaken with little amount of dilute solution of FeCl₃?

Of NH₃ and N₂ which gas will be absorbed more readily on the surface of charcoal and why?

Which names are given if sols have dispersion medium of (a) H₂O, (b) alcohol, (c) benzene?

Write the order of effectiveness of the equimolar solutions of following electrolytes for coagulating a negatively charged sol.
FeCl₃, NaCl, BaCI₂, Th(NO₃)₄.

A sol is prepared by addition of excess of AgNO₃ solution in KI solution. What charge is likely to develop on the colloidal particles?

Which of the following is adsorbed preferably: O₂, NH_3, CO?

Explain the following observations:
(a) Cottrell’s smoke precipitator is fitted at the mouth of the chimney used in factories.
(b) Physical adosption is multi layered, while chemisorption non-tayered.

How are colloids classified on the basis of
(i) physical states of components
(ii) nature of dispersed phase and
(iii) interaction between dispersed phase and dispersion medium?

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?

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

Explain the following term:
(i) Electro-dialysis
(ii) Phases of a colloidal solution.

Explain the following terms with an example of each:
(i) Emulsification,
(ii) Chemisorption.

A colloidal solution of Agl is prepared by two different methods shown below:

(i) What is the charge of AgI colloidal particles in the two test tube (A) and (B).
(ii) Give reason for the origin of change.

(a) What is gel? Give an example.
(b) How is gold sol prepared by reduction method ?

The adsorption of gases on solids can be described by Frundlich’s reaction:
$(\frac{x}{m}) = {kp}^{1 / 4}$

(i) How are the values of k and n determined experimentally?
(ii) Explain why the value of n should be equal to or greater than one?

Explain the following observations:
(a) Ferric hydroxide sol gets coagulated on addition of sodium chloride solution.
(b) Cottrell’s smoke precipitator is fitted at the mouth of the chimney used in factories.
(c) Physical adsorption is multi layered, while chemisorption non layered.

Consider the adsorption isotherm given below and interpret the variation in the extent of adsorption (x/m) when:

(i) temperature increases at constant pressure.
(ii) pressure increases at constant temperature.