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Class 12 NCERT Solutions Chemistry
Class 12 NCERT Solutions Chemistry
Chapter - 2. Electrochemistry
Chapter - 2. Electrochemistry
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1. Arrange the following metals in the order in which they displace each other from the solution of their salts.
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.
Al, Cu, Fe, Mg and Zn.
2. Given the standard electrode potentials,
2. Given the standard electrode potentials,
K+/K = –2.93V, Ag+/Ag = 0.80V,
K+/K = –2.93V, Ag+/Ag = 0.80V,
Hg2+/Hg = 0.79V
Hg2+/Hg = 0.79V
Mg2+/Mg = –2.37 V, Cr3+/Cr = – 0.74V
Mg2+/Mg = –2.37 V, Cr3+/Cr = – 0.74V
3.Depict the galvanic cell in which the reaction
3.Depict the galvanic cell in which the reaction
Zn(s)+2Ag+(aq) →Zn2+(aq)+2Ag(s), takes place. Further show:
Zn(s)+2Ag+(aq) →Zn2+(aq)+2Ag(s), takes place. Further show:
(i) Which of the electrode is negatively charged?
(i) Which of the electrode is negatively charged?
(ii) The carriers of the current in the cell.
(ii) The carriers of the current in the cell.
(iii) Individual reaction at each electrode.
(iii) Individual reaction at each electrode.
4. Calculate the standard cell potentials of galvanic cell in which the following reactions take place:
4. Calculate the standard cell potentials of galvanic cell in which the following reactions take place:
(i) 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd
(i) 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd
(ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s)
(ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s)
Calculate the ∆rGθ and equilibrium constant of the reactions.
Calculate the ∆rGθ and equilibrium constant of the reactions.
5. Write the Nernst equation and emf of the following cells at 298 K:
5. Write the Nernst equation and emf of the following cells at 298 K:
(i) Mg(s)|Mg2+(0.001M)||Cu2+(0.0001M)|Cu(s)
(i) Mg(s)|Mg2+(0.001M)||Cu2+(0.0001M)|Cu(s)
(ii) Fe(s)|Fe2+(0.001M)||H+(1M)|H2(g)(1bar)| Pt(s)
(ii) Fe(s)|Fe2+(0.001M)||H+(1M)|H2(g)(1bar)| Pt(s)
(iii) Sn(s)|Sn2+(0.050M)||H+(0.020M)|H2(g) (1 bar)|Pt(s)
(iii) Sn(s)|Sn2+(0.050M)||H+(0.020M)|H2(g) (1 bar)|Pt(s)
(iv) Pt(s)|Br–(0.010M)|Br2(l)||H+(0.030M)| H2(g) (1 bar)|Pt(s).
(iv) Pt(s)|Br–(0.010M)|Br2(l)||H+(0.030M)| H2(g) (1 bar)|Pt(s).
6. In the button cells widely used in watches and other devices the following reaction takes place:
6. 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)
Zn(s) + Ag2O(s) + H2O(l) → Zn2+(aq) + 2Ag(s) + 2OH–(aq)
Determine ∆r Gθ and Eθ for the reaction.
Determine ∆r Gθ and Eθ for the reaction.
7. Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.
7. Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.
8. The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm–1. Calculate its molar conductivity.
8. The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm–1. Calculate its molar conductivity.
9. The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500 W. What is the cell constant if conductivity of 0.001M KCl solution at 298 K is 0.146 × 10–3 S cm–1 .
9. The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500 W. What is the cell constant if conductivity of 0.001M KCl solution at 298 K is 0.146 × 10–3 S cm–1 .
10. The conductivity of sodium chloride at 298 K has been determined at different concentrations and the results are given below:
10. The conductivity of sodium chloride at 298 K has been determined at different concentrations and the results are given below:
Concentration/ 0.001 0.010 0.020 0.050 0.100
Concentration/ 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
102 × κ/S m–1 1.237 11.85 23.15 55.53 106.74
Calculate Λmfor all concentrations and draw a plot between Λm and c½. Find the value of Λºm .
Calculate Λmfor all concentrations and draw a plot between Λm and c½. Find the value of Λºm .
11. Conductivity of 0.00241 M acetic acid is 7.896 × 10–⁵ S cm–1 . Calculate its molar conductivity. If Λºm for acetic acid is 390.5 S cm2 mol–1 , what is its dissociation constant?
11. Conductivity of 0.00241 M acetic acid is 7.896 × 10–⁵ S cm–1 . Calculate its molar conductivity. If Λºm for acetic acid is 390.5 S cm2 mol–1 , what is its dissociation constant?
12. How much charge is required for the following reductions:
12. How much charge is required for the following reductions:
(i) 1 mol of Al3+ to Al ?
(i) 1 mol of Al3+ to Al ?
(ii) 1 mol of Cu2+ to Cu ?
(ii) 1 mol of Cu2+ to Cu ?
(iii) 1 mol of MnO4 – to Mn2+ ?
(iii) 1 mol of MnO4 – to Mn2+ ?
13. How much electricity in terms of Faraday is required to produce
13. How much electricity in terms of Faraday is required to produce
(i) 20.0 g of Ca from molten CaCl2 ?
(i) 20.0 g of Ca from molten CaCl2 ?
(ii) 40.0 g of Al from molten Al2O3 ?
(ii) 40.0 g of Al from molten Al2O3 ?
14. How much electricity is required in coulomb for the oxidation of
14. How much electricity is required in coulomb for the oxidation of
(i) 1 mol of H2O to O2 ?
(i) 1 mol of H2O to O2 ?
(ii) 1 mol of FeO to Fe2O3 ?
(ii) 1 mol of FeO to Fe2O3 ?
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?
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?
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?
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?
17. Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:
17. Using the standard electrode potentials given in Table 3.1, predict if the reaction between the following is feasible:
(i) Fe3+(aq) and I–(aq) (ii) Ag+ (aq) and Cu(s)
(i) Fe3+(aq) and I–(aq) (ii) Ag+ (aq) and Cu(s)
(iii) Fe3+ (aq) and Br–(aq) (iv) Ag(s) and Fe3+(aq)
(iii) Fe3+ (aq) and Br–(aq) (iv) Ag(s) and Fe3+(aq)
(v) Br2 (aq) and Fe2+(aq).
(v) Br2 (aq) and Fe2+(aq).
18. Predict the products of electrolysis in each of the following:
18. Predict the products of electrolysis in each of the following:
(i) An aqueous solution of AgNO3 with silver electrodes.
(i) An aqueous solution of AgNO3 with silver electrodes.
(ii) An aqueous solution of AgNO3 with platinum electrodes.
(ii) An aqueous solution of AgNO3 with platinum electrodes.
(iii) A dilute solution of H2SO4 with platinum electrodes.
(iii) A dilute solution of H2SO4 with platinum electrodes.
(iv) An aqueous solution of CuCl2 with platinum electrodes.
(iv) An aqueous solution of CuCl2 with platinum electrodes.
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