NCERT Solutions | Class 12 Chemistry Chapter 3

NCERT Solutions | Class 12 Chemistry Chapter 3 | Electro chemistry 

CBSE Solutions | Chemistry Class 12

Check the below NCERT Solutions for Class 12 Chemistry Chapter 3 Electro chemistry Pdf free download. NCERT Solutions Class 12 Chemistry  were prepared based on the latest exam pattern. We have Provided Electro chemistry Class 12 Chemistry NCERT Solutions to help students understand the concept very well.

NCERT | Class 12 Chemistry

NCERT Solutions Class 12 Chemistry

Book:	National Council of Educational Research and Training (NCERT)
Board:	Central Board of Secondary Education (CBSE)
Class:	12th
Subject:	Chemistry
Chapter:	3
Chapters Name:	Electro chemistry
Medium:	English

Electro chemistry | Class 12 Chemistry | NCERT Books Solutions

You can refer to MCQ Questions for Class 12 Chemistry Chapter 3 Electro chemistry to revise the concepts in the syllabus effectively and improve your chances of securing high marks in your board exams.

NCERT Exercises

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 1.

How would you determine the standard electrode potential of the system Mg²⁺ | Mg?

Solution.

Set up an electrochemical cell consisting of MglMgSO₄(1 M) as one electrode by dipping a magnesium wire in 1 M MgSO₄ solution and standard hydrogen electrode Pt, H₂ (1 atm) | H⁺(1 M) as the second electrode. Measure the EMF of the cell and also note the direction of deflection in the voltmeter. The direction of deflection shows that the electrons flow from magnesium electrode to hydrogen electrode, i.e., oxidation takes place on magnesium electrode and reduction on hydrogen electrode.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 2.

Can you store copper sulphate solution in a zinc pot ?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 3.

Consult the table of standard electrode potentials and suggest three substances that can oxidise ferrous ions under suitable conditions.

Solution.

Oxidation of ferrous ions means :

Only those substances can oxidise Fe²⁺ to Fe³⁺ which are stronger oxidising agents and have positive reduction potentials greater than 0.77 V so that EMF of the cell reaction is positive. This is for elements lying below Fe³⁺/Fe²⁺ in the electrochemical series, for example, Br₂, Cl₂ and F₂.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 4.

Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 5.

Calculate the emf of the cell in which the following reaction takes place :
Ni_(S) + 2Ag⁺ (0.002 M) → Ni²⁺(0.160 M) + 2Ag_(S)
Given that E°cell = 1.05 V

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 6.

The cell in which the following reaction occurs: 2Fe³⁺_(aq) + 2l^–_(aq) → 2Fe²⁺_(aq) + l_2(s) has E°cell = 0.236 V at 298 K. Calculate the standard Gibb’s energy and the equilibrium constant of the cell reaction.

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 7.

Why does the conductivity of a solution decrease with dilution?

Solution.

Conductivity of solution decreases with dilution because number of ions per unit volume decreases.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 8.

Suggest a way to determine the A°m value of water.

Solution.

Water is a weak electrolyte. Its A°m value can be determined with the help of Kohlrausch’s law.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 9.

The molar conductivity of 0.025 mol L^-1 methanoic acid is 46.1 S cm² mol^-1. Calculate its degree of dissociation and dissociation constant. Given λ (H⁺) = 349.6 S cm² mol^-1 and λ (HCOO^–) = 54.6 S cm² mol^-1

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 10.

lf a current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons would flow though the wire?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 11.

Suggest; a list of metals that are extracted electrolytically.

Solution.

Ca, Na, K, Al are extracted electrolytically.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 12.

Consider the reaction:
Cr₂O^2-₇ + 14H⁺ + 6e^– → 2Cr³⁺ + 7H₂O,
What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr₂ O^2-₇?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 13.

Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.

Solution.

Chemical reactions while recharging :
2PbSO₄ + 2H₂O → PbO₂ + Pb + 2H₂SO₄
Electricity is passed through the electrolyte PbSO₄ which is converted into PbO₂ and Pb.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 14.

Suggest two materials other than hydrogen that can be used as fuels in fuel cells.

Solution.

CH₄ and CO can be used in fuel cell instead of hydrogen.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 15.

Explain how rusting of iron is envisaged as setting up of an electrochemical cell.

Solution.

The following reactions take place at the surface of iron metal which acts as an electrochemical cell.

The water layer present on the surface of iron dissolves acidic oxides of air like C0₂ to form acids which dissociate to give H⁺ ions. Fe starts losing electrons in presence of H⁺ ions.
H₂O + CO₂ → H₂CO₃ \(\rightleftharpoons \) 2H⁺ + C0₃^2-

NCERT Exercises

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 1.

Arrange the following metals in the order in which they displace each other from the solution of their salts.
Al, Cu, Fe, Mg and Zn.

Solution.

Mg, Al, Zn, Fe, Cu

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 2.

Given the standard electrode potentials,
K⁺/ K = – 2.93 V, Ag⁺/ Ag = 0.80 V, Hg²⁺/ Hg = 0.79 V, Mg²⁺/ Mg = -2.37 V, Cr³⁺/ Cr = – 0.74 V
Arrange these metals in their increasing order of reducing power.

Solution.

Higher the oxidation potential, more easily it is oxidized and hence greater is the reducing power. Thus, increasing order of reducing power will be
Ag < Hg < Cr < Mg < K.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 3.

Depict the galvanic cell in which the reaction Zn_(S) + 2Ag⁺_(aq) Zn²⁺_(aq), + 2Ag_(s) takes place. Further show :

1. Which of the electrode is negatively charged?
2. The carriers of the current i n the cell.
3. Individual reaction at each electrode.

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 4.

Calculate the standard cell potentials of galvanic cell in which the following reactions take place :

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 5.

Write the Nernst equation and emf of the following cells at 298 K :

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 6.

In the button cells widely used in watches and other devices the following reaction takes place :

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 7.

Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

Solution.

The reciprocal of resistivity is known as specific conductance or simply conductivity. It is denoted by K (kappa). Thus, if K is the specific conductance and G is the conductance of the solution, then

Now, if I = 1 cm and A = lsq.cm, then K = G.

Hence, conductivity of a solution is defined as the conductance of a solution of 1 cm length and having 1 sq. cm as the area of cross¬section. Alternatively, it may be defined as conductance of one centimetre cube of the solution of the electrolyte.

Molar conductivity of a solution at a dilution V is the conductance of all the ions produced from 1 mole of the electrolyte dissolved in V cm³ of the solution when the electrodes are one cm apart and the area of the electrodes is so large that the whole of the solution is contained between them. It is represented by ∆_m.

Variation of conductivity and molar conductivity with concentration: Conductivity always decreases with decrease in concentration, for both weak and strong electrolytes. This is because the number of ions per unit volume that carry the current in a solution decreases on dilution.

Molar conductivity increases with decrease in concentration. This is because that total volume, V, of solution containing one mole of electrolyte also increases. It has been found that decrease in K on dilution of a solution is more than compensated by increase in its volume.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 8.

The conductivity of 0.20 M solution of KCI at 298 K is 0.0248 S cm^-1. Calculate its molar conductivity.

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 9.

The resistance of a conductivity cell containing 0.001 M KCI solution at 298 K is 1500 Ω. What is the cell constant if conductivity of 0.001 M KCI solution at 298 K is 0.146 × 10^-3 S cm^-1.

Solution.

Cell constant = K × R = 0.146 × 10^-3 × 1500 = 0.219 cm^-1

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 10.

The conductivity of sodium chloride at 298K has been determined at different concentrations and the results are given below:
Concentration/M 0.001 0.010 0.020 0.050 0.100
10² × K/S m^-1 1.237 11.85 23.15 55.53 106.74
Calculate ∆_m for all concentrations and draw a plot between ∆_m and c^1/2. Find the value of ∆°_m

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 11.

Conductivity of 0.00241 M acetic acid is 7.896 × 10^-5 S cm^-1. Calculate its molar conductivity. If ∆°_m for acetic acid is 390.5 S cm² mol^-1, what is its dissociation constant?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 12.

How much charge is required for the following reductions:

1. 1 mol of Al³⁺to Al ?
2. 1 mol of Cu²⁺ to Cu ?
3. 1 mol of MnO₄^– to Mn²⁺ ?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 13.

How much electricity in terms of Faraday is required to produce

1. 20.0 g of Ca from molten CaCl₂?
2. 40.0 g of Al from molten Al₂O₃?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 14.

How much electricity is required in coulomb for the oxidation of

1. 1 mol of H₂O to O₂?
2. 1 mol of FeO to Fe₂O₃?

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 15.

A solution of Ni(NO₃)₂ is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?
(At. mass of Ni = 58.7)

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 16.

Three electrolytic cells A, B, C containing solutions of ZnSO₄, AgNO₃ and CuSO₄ respectively are connected in series. A steady current of 1.5 amperes was passed through them until 1.45 g of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?
(At. wt. of Ag = 108, Cu = 63.5, Zn = 65.3)

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 17.

Using the standard electrode potentials predict if the reaction between the following is feasible :

Solution.

NCERT Solutions for Class 12 Chemistry Chapter 3, Question 18.

Predict the product of electrolysis in each of the following:

1. An aqueous solution of AgNO₃ with silver electrodes.
2. An aqueous solution of AgNO₃ with platinum electrodes.
3. A dilute solution of H₂SO₄ with platinum electrodes.
4. An aqueous solution of CuCI₂ with platinum electrodes.

Solution.

NCERT Class 12 Chemistry

Class 12 Chemistry Chapters | Chemistry Class 12 Chapter 3

Chapterwise NCERT Solutions for Class 12 Chemistry

NCERT Solutions For Class 12 Chemistry Chapter 1 The Solid State
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions
NCERT Solutions For Class 12 Chemistry Chapter 3 Electro chemistry
NCERT Solutions For Class 12 Chemistry Chapter 4 Chemical Kinetics
NCERT Solutions For Class 12 Chemistry Chapter 5 Surface Chemistry
NCERT Solutions For Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements
NCERT Solutions For Class 12 Chemistry Chapter 7 The p Block Elements
NCERT Solutions For Class 12 Chemistry Chapter 8 The d and f Block Elements
NCERT Solutions For Class 12 Chemistry Chapter 9 Coordination Compounds
NCERT Solutions For Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes
NCERT Solutions For Class 12 Chemistry Chapter 11 Alcohols Phenols and Ethers
NCERT Solutions For Class 12 Chemistry Chapter 12 Aldehydes Ketones and Carboxylic Acids
NCERT Solutions For Class 12 Chemistry Chapter 13 Amines
NCERT Solutions For Class 12 Chemistry Chapter 14 Biomolecules
NCERT Solutions For Class 12 Chemistry Chapter 15 Polymers
NCERT Solutions For Class 12 Chemistry Chapter 16 Chemistry in Everyday Life

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