1. In the electrolysis of water, suppose 0.076 L of O2 is collected at 25oC and 755 mmHg. How many faradays of
electricity passed through the solution?
[Ans. 1158 Coulomb]
2. What is the hourly production rate of chlorine gas (in Kg) from an electrolytic cell using aqueous NaCl electrolyte and
carrying a current of 1.5 × 103 A? The anode efficiency for the oxidation of Cl– is 93%.
[Ans. 1.8475 Kg / hr]
4. A solution containing H and D ions is in equilibrium with a mixture of H2 and D2 gases at 25 C. If the partial pressure
+ + o
0
of both the gases are 1.0 atm, calculate the ratio [D+]/[H+], E D / D 2 = – 0.003 V..
[Ans. 1.122]
5. A current of 2.6 amp is passed through 25 ml, 0.8 N Fe2(SO4)3 solution for 3 minutes with a current efficiency of
95%. Find out the molarity of ferric ion after the electrolysis. Assume no volume change.
[Ans. 0.0827 M]
6. What amount (in gms) of nitrobenzene can be reduced to aniline by the same amount of electricity which is required
to produce 0.52 gm of anthraquinone (C14H8O2) by anodic oxidation of anthracene (C14H10). If the potential drop
across the cell is 2.5 volt then how much energy will be consumed?
[Ans. 0.40125 gm, 3.61875 kJ]
7. Calculate the standard reduction potential of electrode H2O | H2, OH– at 25oC. [Ans. 0.826 V]
8. How long a current of 3 amp has to be passed through a solution of AgNO3 to coat a metal surface of area 80 cm2
with a thickness of 0.005 mm? Density of Ag is 10.5 g cm–3.
[Ans. 125.09 Sec]
9. Show that E 0Fe 3 / Fe 3E 0Fe 3 / Fe 2 E 0Fe 2 / Fe
10. A current of 0.193 amp is passed through 100 ml of 0.2 M NaCl for an hour. Calculate p H of solution after
electrolysis if current efficiency is 90%. Assume no volume change.
[Ans. 12.82]
11. The voltage of the following cell is 0.987 V
PT (H2) (1 atm) | HOCN(1.4 × 10–3 M) | | Ag+(0.8 M) | Ag(s)
0
Calculate Ka of HOCN, E Ag / Ag = 0.80 V
[Ans. Ka = 2.15 × 10–4]
12. Given the cell Cd | Cd (OH)2(s) | NaOH (0.01 mol kg ) | H2 (1 atm) | Pt
–1
With ECell = 0.0 V at 298 K. If E 0Cd 2 / Cd 0.40V , Calculate Ksp for Cd(OH)2
[Ans. 3.36 × 10–15 M2]
13. For the reaction 4 Al(s) + 3O2(g) + 6H2O + 4OH- 4[Al(OH)4]- E 0Cell 2.73V
if G f OH 157 kJ / mol and G 0f H 2 O 237.2 kJ / mol
0
Determine G 0f AlOH 4 .
[Ans. 1.3 × 103 kJ/mol]
14*. For the galvanic cell
Ag | AgCl(s), KCl (0.2 M) | | KBr (0.001M), AgBr(s) | Ag
calculate the EMF generated and assign correct polarity to each electrode for a spontaneous process after taking an
account of cell reaction at 25oC.
Given KSP (AgCl) = 2.8 × 10–10, KSP(AgBr) = 3.3 × 10–13.
[Ans. – 0.037 (since Ecell is -ve therefore polarity of cell should be reversed)]
15. Zinc granules are added in excess to 750 ml of 1.5 M Ni (NO3)2 solution at 30oC until the equilibrium is reached. If
EMF of cell Zn(s) | Zn +2 (1M) || H + (1M) | H 2 (g) (1 atm), Pt is 0.76 volt and that of cell
Ni | Ni+2 (1M) | | H+(pH = 0) | H2(g) (1atm), Pt is 0.24 volt, then calculate [Ni+2] at equilibrium. Also find the amount
of Zn consumed. (Zn = 65).
[Ans. 7 × 10–18 M, 73.125 gm]
electricity passed through the solution?
[Ans. 1158 Coulomb]
2. What is the hourly production rate of chlorine gas (in Kg) from an electrolytic cell using aqueous NaCl electrolyte and
carrying a current of 1.5 × 103 A? The anode efficiency for the oxidation of Cl– is 93%.
[Ans. 1.8475 Kg / hr]
4. A solution containing H and D ions is in equilibrium with a mixture of H2 and D2 gases at 25 C. If the partial pressure
+ + o
0
of both the gases are 1.0 atm, calculate the ratio [D+]/[H+], E D / D 2 = – 0.003 V..
[Ans. 1.122]
5. A current of 2.6 amp is passed through 25 ml, 0.8 N Fe2(SO4)3 solution for 3 minutes with a current efficiency of
95%. Find out the molarity of ferric ion after the electrolysis. Assume no volume change.
[Ans. 0.0827 M]
6. What amount (in gms) of nitrobenzene can be reduced to aniline by the same amount of electricity which is required
to produce 0.52 gm of anthraquinone (C14H8O2) by anodic oxidation of anthracene (C14H10). If the potential drop
across the cell is 2.5 volt then how much energy will be consumed?
[Ans. 0.40125 gm, 3.61875 kJ]
7. Calculate the standard reduction potential of electrode H2O | H2, OH– at 25oC. [Ans. 0.826 V]
8. How long a current of 3 amp has to be passed through a solution of AgNO3 to coat a metal surface of area 80 cm2
with a thickness of 0.005 mm? Density of Ag is 10.5 g cm–3.
[Ans. 125.09 Sec]
9. Show that E 0Fe 3 / Fe 3E 0Fe 3 / Fe 2 E 0Fe 2 / Fe
10. A current of 0.193 amp is passed through 100 ml of 0.2 M NaCl for an hour. Calculate p H of solution after
electrolysis if current efficiency is 90%. Assume no volume change.
[Ans. 12.82]
11. The voltage of the following cell is 0.987 V
PT (H2) (1 atm) | HOCN(1.4 × 10–3 M) | | Ag+(0.8 M) | Ag(s)
0
Calculate Ka of HOCN, E Ag / Ag = 0.80 V
[Ans. Ka = 2.15 × 10–4]
12. Given the cell Cd | Cd (OH)2(s) | NaOH (0.01 mol kg ) | H2 (1 atm) | Pt
–1
With ECell = 0.0 V at 298 K. If E 0Cd 2 / Cd 0.40V , Calculate Ksp for Cd(OH)2
[Ans. 3.36 × 10–15 M2]
13. For the reaction 4 Al(s) + 3O2(g) + 6H2O + 4OH- 4[Al(OH)4]- E 0Cell 2.73V
if G f OH 157 kJ / mol and G 0f H 2 O 237.2 kJ / mol
0
Determine G 0f AlOH 4 .
[Ans. 1.3 × 103 kJ/mol]
14*. For the galvanic cell
Ag | AgCl(s), KCl (0.2 M) | | KBr (0.001M), AgBr(s) | Ag
calculate the EMF generated and assign correct polarity to each electrode for a spontaneous process after taking an
account of cell reaction at 25oC.
Given KSP (AgCl) = 2.8 × 10–10, KSP(AgBr) = 3.3 × 10–13.
[Ans. – 0.037 (since Ecell is -ve therefore polarity of cell should be reversed)]
15. Zinc granules are added in excess to 750 ml of 1.5 M Ni (NO3)2 solution at 30oC until the equilibrium is reached. If
EMF of cell Zn(s) | Zn +2 (1M) || H + (1M) | H 2 (g) (1 atm), Pt is 0.76 volt and that of cell
Ni | Ni+2 (1M) | | H+(pH = 0) | H2(g) (1atm), Pt is 0.24 volt, then calculate [Ni+2] at equilibrium. Also find the amount
of Zn consumed. (Zn = 65).
[Ans. 7 × 10–18 M, 73.125 gm]
