1. From the following information, Calculate the solubility product of AgBr. Given:
AgBr(s) + e– Ag(s) + Br– (aq) ; Eo = 0.07 V
Ag+ (aq) + e, Ag(s); Eo = 0.80 V
[Ans. 4.5 × 10–13 M2]
2. An aq. solution of CuCl2 containing 2.69 gm of it is electrolysed untill all the copper is deposited. The electrolysis is
continued for 19.3 more minutes witth volume of the solution kept at 2 litre and the current at 2.5 amp having 80%
efficiency. Find the volume of gases evolved measured at N.T.P. during entire electrolysis. Also find the number of
faradays required in the first part of electrolysis (i.e., until all the copper is deposited) assuming 80% current
efficiency. Find the amount of copper deposited.
[Ans. 0.05 F, 0.448 L Cl2, H2, 0.1344 L O2]
3. A lead storage cell is discharged which causes the H2SO4 electrolyte to change from a concentration of 40% by
weight (density 1.256 gm/ml) to one of 30% by weight. The original volume of electrolyte is 1.2 litre. How many
faradays have left the anode of the battery. Note that water is produced by the cell reaction as H2SO4 is used up.
Overall reaction is
Pb(s) + PbO2(s) + 2H2SO4(l) 2PbSO4(s) + 2H2O(l)
[Ans. 2.036 F]
4. Calculate the equilibrium constant for the reaction
Fe+2 + Ce+4 Fe+3 + Ce+3 Given : Ecell for
Pt, H2(g) (190 mm Hg) | H+ (10–7 M) | | Ce+4 (0.2 M) | Ce+3 (1M), Pt is 1.794V and
E 0Fe / Fe 2 0.44 V , E 0Fe 3 / Fe 0.04 V
[Ans.Keq = 3.205 × 1011]
5*. Calculate EMF of the following cell
Ag(s) | Ag2CrO4 (Sat. solution) | | KBr(0.002 M), AgBr (s) | Ag(s)
Given KSP (Ag2CrO4) = 4 × 10–12 and that AgBr is 2 × 10–13
[Ans. – 0.3724 V]
6. For the reaction: H2(g) + 2AgCl(s) + 2H2O(l) 2Ag(s) + 2H3O + 2Cl at 25 C
+ – o
The standard free energy of formation of AgCl(s), H2O(l), H3O+, Cl– are – 110, – 237, (–200 – ,
(–168 + ) kJ/mol (where is not known). Calculate the cell voltage if this reaction is run at 25oC and 0.8 atm in a
cell in which [H3O+] and [Cl–] are 0.006 M and 0.02 M respectively.
[Ans. 0.446 V]
7. A silver rod and a SHE are dipped into a saturated aqueous solution of silver oxalate, Ag2C2O4 at 25oC. The
measured potential difference between the rod and the SHE is 0.589 V, the rod being positive. Calculate the solubility
o
product of silver oxalate. Given E Ag + / Ag = + 0.8 V
[Ans. 9.7 × 10–12 M3]
8. When AgCl is dissolved in a large excess of NH3, practically all silver can be assumed to exist in the form of a single
species Agm(NH3)n+m. Compute the values of m and n using the following two cells.
Ag | 0.379 × 10–3 M AgCl, 1M NH3 | | 37.9 × 10–3 M AgCl, 1 M NH3 | Ag
ECell = 0.1185 V at 298 K
Ag | 3.4 × 10–2 M AgCl, 1 M NH3| | 3.4 × 10–2 M AgCl, 0.1 M NH3 | Ag
ECell = 0.1263 V at 298 K [Ans. m = 1, n = 2]
AgBr(s) + e– Ag(s) + Br– (aq) ; Eo = 0.07 V
Ag+ (aq) + e, Ag(s); Eo = 0.80 V
[Ans. 4.5 × 10–13 M2]
2. An aq. solution of CuCl2 containing 2.69 gm of it is electrolysed untill all the copper is deposited. The electrolysis is
continued for 19.3 more minutes witth volume of the solution kept at 2 litre and the current at 2.5 amp having 80%
efficiency. Find the volume of gases evolved measured at N.T.P. during entire electrolysis. Also find the number of
faradays required in the first part of electrolysis (i.e., until all the copper is deposited) assuming 80% current
efficiency. Find the amount of copper deposited.
[Ans. 0.05 F, 0.448 L Cl2, H2, 0.1344 L O2]
3. A lead storage cell is discharged which causes the H2SO4 electrolyte to change from a concentration of 40% by
weight (density 1.256 gm/ml) to one of 30% by weight. The original volume of electrolyte is 1.2 litre. How many
faradays have left the anode of the battery. Note that water is produced by the cell reaction as H2SO4 is used up.
Overall reaction is
Pb(s) + PbO2(s) + 2H2SO4(l) 2PbSO4(s) + 2H2O(l)
[Ans. 2.036 F]
4. Calculate the equilibrium constant for the reaction
Fe+2 + Ce+4 Fe+3 + Ce+3 Given : Ecell for
Pt, H2(g) (190 mm Hg) | H+ (10–7 M) | | Ce+4 (0.2 M) | Ce+3 (1M), Pt is 1.794V and
E 0Fe / Fe 2 0.44 V , E 0Fe 3 / Fe 0.04 V
[Ans.Keq = 3.205 × 1011]
5*. Calculate EMF of the following cell
Ag(s) | Ag2CrO4 (Sat. solution) | | KBr(0.002 M), AgBr (s) | Ag(s)
Given KSP (Ag2CrO4) = 4 × 10–12 and that AgBr is 2 × 10–13
[Ans. – 0.3724 V]
6. For the reaction: H2(g) + 2AgCl(s) + 2H2O(l) 2Ag(s) + 2H3O + 2Cl at 25 C
+ – o
The standard free energy of formation of AgCl(s), H2O(l), H3O+, Cl– are – 110, – 237, (–200 – ,
(–168 + ) kJ/mol (where is not known). Calculate the cell voltage if this reaction is run at 25oC and 0.8 atm in a
cell in which [H3O+] and [Cl–] are 0.006 M and 0.02 M respectively.
[Ans. 0.446 V]
7. A silver rod and a SHE are dipped into a saturated aqueous solution of silver oxalate, Ag2C2O4 at 25oC. The
measured potential difference between the rod and the SHE is 0.589 V, the rod being positive. Calculate the solubility
o
product of silver oxalate. Given E Ag + / Ag = + 0.8 V
[Ans. 9.7 × 10–12 M3]
8. When AgCl is dissolved in a large excess of NH3, practically all silver can be assumed to exist in the form of a single
species Agm(NH3)n+m. Compute the values of m and n using the following two cells.
Ag | 0.379 × 10–3 M AgCl, 1M NH3 | | 37.9 × 10–3 M AgCl, 1 M NH3 | Ag
ECell = 0.1185 V at 298 K
Ag | 3.4 × 10–2 M AgCl, 1 M NH3| | 3.4 × 10–2 M AgCl, 0.1 M NH3 | Ag
ECell = 0.1263 V at 298 K [Ans. m = 1, n = 2]
