Consider the following relations for emf of an electrochemical cell:
| (a) | emf of a cell = (Oxidation potential of the anode) – (Reduction potential of the cathode) |
| (b) | emf of a cell = (Oxidation potential of the anode) + (Reduction potential of the cathode) |
| (c) | emf of a cell = (Reduction potential of the anode) + (Reduction potential of the cathode) |
| (d) | emf of a cell = (Oxidation potential of the anode) – (Oxidation potential of the cathode) |
Which of the following combinations correctly represents the relation for the emf of the cell?
| 1. | (a) and (b) | 2. | (c) and (d) |
| 3. | (b) and (d) | 4. | (c) and (a) |
The correct expression that represents the equivalent conductance at infinite dilution of is:
(Given that are the equivalent conductances at infinite dilution of the respective ions)
1.
2.
3.
4.
Molar conductivities at infinite dilution of
NaCl, HCl, and are 126.4, 425.9, and 91.0 S cm2 mol–1 respectively.
for will be:
| 1. | \(180.5~S~cm^2~mol^{-1}\) | 2. | \(290.8~S~cm^2~mol^{-1}\) |
| 3. | \(390.5~S~cm^2~mol^{-1}\) | 4. | \(425.5~S~cm^2~mol^{-1}\) |
The Gibb's energy for the decomposition of \(\mathrm{A l_{2} O_{3}}\) at \(\mathrm{500~ ^\circ C}\) is as follows:
2/3Al2O3 → 4/3Al + O2 ; ∆rG = + 960 k J mol–1
The potential difference needed for the electrolytic reduction of aluminium oxide (Al2O3) at \(\mathrm{500~ ^\circ C}\) is at least,
1. 3.0 V
2. 2.5 V
3. 5.0 V
4. 4.5 V
| 1. | –4.18 V and Yes | 2. | +0.33 V and Yes |
| 3. | +2.69 V and No | 4. | –2.69 V and No |
| 1. | 4.0 | 2. | 20.0 |
| 3. | 40.0 | 4. | 0.66 |
A hypothetical electrochemical cell is shown below.
A|A+(x M) || B+(y M)|B
The Emf measured is +0.20 V. The cell reaction is:
1. A+ + B → A + B+
2. A+ + e- → A ; B+ + e- → B
3. The cell reaction cannot be predicted.
4. A + B+ → A+ + B
If = -0.441 V and = 0.771 V, the standard emf of the reaction:
Fe + 2Fe3+→ 3Fe2+ will be:
| 1. | 0.330 V | 2. | 1.653 V |
| 3. | 1.212 V | 4. | 0.111 V |
| 1. | 17.6 mg | 2. | 21.3 mg |
| 3. | 24.3 mg | 4. | 13.6 mg |
The efficiency of a fuel cell is given by:
1.
2.
3.
4.