CBSE (Science) Class 12CBSE
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NCERT solutions Chemistry Class 12 Part 1 chapter 3 Electrochemistry

Chapters

NCERT Chemistry Class 12 Part 1

Chemistry Textbook for Class 12 Part 1

Chapter 3 - Electrochemistry

Pages 68 - 90

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

Q 1 | Page 68

Can you store copper sulphate solutions in a zinc pot?

Q 2 | Page 68

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

Q 3 | Page 68

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

Q 4 | Page 73

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

Q 5 | Page 73

The cell in which the following reactions occurs: 2Fe3+ (aq) + 2I– (aq) —> 2Fe2+ (aq) +I2 (s) has E°cell=0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.

 

Q 6 | Page 73

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 andλ°(HCOO-) = 54.6 S cm2 mol-1

Q 9 | Page 83

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

Q 10 | Page 86

Suggest a list of metals that are extracted electrolytically.

Q 11 | Page 86

Consider the reaction: Cr2O72--+ 14H+ + 6e- -> 2Cr3+ + 7H2O What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O72- ?

Q 12 | Page 86

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

Q 13 | Page 90

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

Q 14 | Page 90

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

Q 15 | Page 90

Pages 91 - 92

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

Q 1 | Page 91

Given the standard electrode potentials,

K+/K = −2.93V, Ag+/Ag = 0.80V,

Hg2+/Hg = 0.79V

Mg2+/Mg = −2.37 V, Cr3+/Cr = − 0.74V

Arrange these metals in their increasing order of reducing power.

Q 2 | Page 91

Depict the galvanic cell in which the reaction Zn(s) + 2Ag+(aq) → Zn2+(aq) + 2Ag(s) takes place. Further show:

(i) Which of the electrode is negatively charged?

(ii) The carriers of the current in the cell.

(iii) Individual reaction at each electrode.

Q 3 | Page 91

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

(i) 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd

(ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s)

Calculate the ΔrGθ and equilibrium constant of the reactions.

Q 4 | Page 91

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

(i) Mg(s) | Mg2+(0.001M) || Cu2+(0.0001 M) | Cu(s)

(ii) Fe(s) | Fe2+(0.001M) || H+(1M)|H2(g)(1bar) | Pt(s)

(iii) Sn(s) | Sn2+(0.050 M) || H+(0.020 M) | H2(g) (1 bar) | Pt(s)

(iv) Pt(s) | Br2(l) | Br(0.010 M) || H+(0.030 M) | H2(g) (1 bar) | Pt(s).

Q 5 | Page 91

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

Zn(s) + Ag2O(s) + H2O(l) → Zn2+(aq) + 2Ag(s) + 2OH(aq)

Determine `triangle_rG^Theta` and `E^Theta` for the reaction.

 

Q 6 | Page 91

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

Q 7 | Page 91

The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 Scm−1. Calculate its molar conductivity.

Q 8 | Page 91

Predict the products of electrolysis in each of the following:

An aqueous solution of CuCl2 with platinum electrodes.

Q 8.41 | Page 92

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

Q 9 | Page 91

The conductivity of sodium chloride at 298 K 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 × κ/S m–1 1.237 11.85 23.15 55.53 106.74

Calculate `Lambda_m` for all concentrations and draw a plot between `Lambda_m` and `c^(1/2)` Find the value of `Lambda_m^0`

Q 10 | Page 92

Conductivity of 0.00241 M acetic acid is 7.896 × 10−5 S cm−1. Calculate its molar conductivity and if `Lambda_m^0` for acetic acid is 390.5 S cm2 mol−1, what is its dissociation constant?

Q 11 | Page 92

How much charge is required for the following reductions: 1 mol of Al3+ to Al.

Q 12.1 | Page 92

How much charge is required for the following reductions: 1 mol of Cu2+ to Cu.

Q 12.2 | Page 92

How much charge is required for the following reductions: 1 mol of `MnO_4^(-)` to Mn2+.

Q 12.3 | Page 92

How much electricity is required in coulomb for the oxidation of 1 mol of H2O to O2.

Q 14.1 | Page 92

How much electricity is required in coulomb for the oxidation of 1 mol of FeO to Fe2O3.

Q 14.2 | Page 92

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?

Q 15 | Page 92

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?

Q 16 | Page 92

Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

Fe3+(aq) and I(aq)

Q 17.1 | Page 92

Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

Ag+ (aq) and Cu(s)

Q 17.2 | Page 92

Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

Fe3+ (aq) and Br− (aq)

Q 17.3 | Page 92

Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

Ag(s) and Fe3+ (aq)

Q 17.4 | Page 92

Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:

Br(aq) and Fe2+ (aq).

Q 17.5 | Page 92

Predict the products of electrolysis in each of the following:

An aqueous solution of AgNO3 with silver electrodes.

 

Q 18.1 | Page 92

Predict the products of electrolysis of the following:

An aqueous solution of AgNO3with platinum electrodes.

Q 18.2 | Page 92

Predict the products of electrolysis in each of the following:

A dilute solution of H2SO4with platinum electrodes.

Q 18.3 | Page 92

NCERT Chemistry Class 12 Part 1

Chemistry Textbook for Class 12 Part 1
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