Chemistry Clear Point Dr.

Haseeb Ahmed Mob: +91-89584 51856

Electrochemistry
Daily Practice Problems Haloalkane – Cell
and Haloarene Set - 15
1. Zinc rod is dipped in 0.1M solution of ZnSO4 . 10. Calculate Eᵒcell for the following reaction at
The salt is 95% dissociated at this dilution at 298K: 2Cr(s) + 3Fe2+ (0.01M)  2Cr3+ (0.01M)
298 K. Calculate the electrode potential given + 3Fe(s) (Given: Ecell = 0.261V) Ans: 0.2807 V
that E (Zn2+|Zn) = − 0.76 V. Ans: -0.79 V
11. The EMF of the cell,
2. If E° for copper electrode is + 0.34 V, how will
Zn | Zn2+ (0.1M) || Cd2+ (M1) | Cd
you calculate e.m.f. value when the solution in
contact with it is 0.1 M in copper ions? How has been found to be 0.3305 V at 298 K.
does e.m.f. for copper electrode change when Calculate the value of M1 [E (Zn2+ | Zn) = −
concentration of Cu2+ ion in the solution is 0.76V, E (Cd2+ | Cd) = − 0.40V]. Ans: 0.01 M
decreased? Ans: 0.31 V 12. A copper-silver cell is set up. The copper ion
3. Calculate the reduction potential of the concentration is 0.10 M. The concentration of
following electrode at 298 K: silver ion is not known. The cell potential when
measured was 0.422 V. Determine the
PtCl2 (2.5atm)|HCl (0.01M); E Cl2 | 2 Cl– = 1.36
concentration of silver ions in the cell.
V Ans: 1.49 V
(Given E Ag+/Ag = + 0.80 V, E Cu2+/Cu = +
4. (a) Calculate the electrode potential of a silver
0.34V). Ans: 0.0717 M
electrode dipped in a 0.1M solution of silver
nitrate at 298 K assuming AgNO3 to be 13. Calculate emf of the following cell at 298 K:
completely dissociated. The standard electrode Mg(s)|Mg2+ (0.1M) || Cu2+ (0.01M)| Cu(s).
potential of Ag+ | Ag is 0.80 V at 298 K. Given E°cell = +2.71 V, F = 96500 C mol–1
(b) At what concentration of silver ions will this Ans: 2.6805 V
electrode have a potential of 0 volt? Ans: 0.741 14. Calculate the potential of the following cell
V, 2.76 x 10-14 M.
rection at 298 K : Sn4+ (1.50 M) + Zn (s)  Sn2+
5. Calculate the potential for half-cell containing (0.5 M) + Zn2+ (2.0 M) The standard potential of
0.10 M K2Cr2O7(aq), 0.20 M Cr3+ (aq) and 1.0 × the cell is 0.89 V. Will the potential of the cell
10–4 M H+ (aq) The half-cell reaction is: will increase or decrease if the concentration of
Sn2+ is increased in the cell? Ans: 0.895 V
Cr2O72− (aq) + 14H+ (aq) + 6e–  2Cr3+(aq) +
7H2O (l) 15. Consider a cell composed of the following half
cells:
and the standard electrode potential is given as
E°=1.33V Ans: 0.78 V (i) Mg (s) |Mg2+ (aq) and
6. Calculate the standard electrode potential of (ii) Ag(s) | Ag+ (aq) The e.m.f. of the cell is 2.96
Ni2+ | Νi electrode if the cell potential of the cell: V at [Mg2+] = 0.130 M and [Ag+] = 1.0 × 10–4 M.
Ni | Ni2+ (0.01M) || Cu2+ (0.1 M) | Cu is 0.59 V Calculate the standard e.m.f. of the cell (R = 8.3
Given : E Cu2+ | Cu = 0.34 V. Ans: -0.2205 V JK–1 mol–1, F = 96500 C). Ans: 3.17 V
7. Write the Nernst equation and calculate the 16. Calculate the e.m.f. of the cell at 25°C Zn |
e.m.f. of the following cell at 298 K: Cu(s) | Cu2+ Zn2+(0.01 M) || Fe2+ (0.005 M) | Fe E (Zn2+ | Zn)
(0.130 M) || Ag+ (1.0 × 10–4 M)) | Ag (s) = − 0.763 V and E (Fe2+ | Fe) = − 0.44 V. Ans:
0.314 V
Given: E (Cu2+ | Cu) = + 0.34V and E (Ag+ | Ag)
= + 0.80V Ans: 0.25 V 17. Calculate e.m.f. of the following cell at 298K
2Cr(s) + 3Fe2+ (0.1M)  2Cr3+(0.01M) + 3Fe(s)
8. Represent the cell in which the following
Given : E°(Cr3+ | Cr) = − 0.74 V, E°(Fe2+ | Fe) =
reaction takes place:
− 0.44 V. Ans: 0.31 V
Mg (s) + 2Ag+ (0.0001M)  Mg2+ (0.130M) +
2Ag(s) Calculate its E if Eºcell is 3.17 V. Ans:
2.96 V
9. Calculate the e.m.f. of the following cell: Cd |
Cd2+ (0.01M) || H+ (0.02M) | Pt, H2(0.8 atm)
Given: E° (Cd2+ | Cd) = – 0.40 V. Ans: 0.36 V
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