The potential of hydrogen electrode in contact with a solution with pH =10, is:
1. −0.0591 V1. | Cu & Zn2+ | 2. | Zn & Cu |
3. | Cu2+ & Zn2+ | 4. | Cu2+ & Zn |
1. | Increases | 2. | Decreases |
3. | Unchanged | 4. | Can't be predicted |
a. | It is also known as the Leclanche cell. |
b. | The electrolyte is a moist paste of ammonium chloride (NH4Cl) and zinc chloride (ZnCl2 ). |
c. | The cathodic reaction is : MnO2 + NH4++ e-→ MnO(OH) + NH3 |
1. | Only a and b are correct | 2. | Only c is correct |
3. | Only b and c are correct | 4. | All are correct |
\(\land^o_m\) for NaCl, HCl and \(\mathrm{CH_3COONa }\) are 126.4, 425.9, and 91.05 S cm2 mol–1 respectively. If the conductivity of 0.001028 mol L–1 acetic acid solution is \(4.95 \times 10^{-5} S ~cm^{-1} \), the degree of dissociation of the acetic acid solution is-
1. | 0.01233 | 2. | 1.00 |
3. | 0.1233 | 4. | 1.233 |
Aluminium oxide may be electrolysed at 1000 °C to furnish aluminium metal.
The cathode reaction is Al3+ + 3e- → Al.
To prepare 5.12 kg of aluminium metal by this method would require:
(Atomic mass = 27 amu; 1 faraday=96,500 Coulombs)
1. 5.49×101 C of electricity
2. 5.49×104 C of electricity
3. 1.83×107 C of electricity
4. 5.49×107 C of electricity
Two half cell reactions are given below:
\(\begin{aligned} &\mathrm{Co}^{3+}+e^{-} \rightarrow \mathrm{Co}^{2+}, \mathrm{E}_{\mathrm{Co}^{2+} / \mathrm{Co}^{3+}}^{\circ}=-1.81 \mathrm{~V} \\ &2 \mathrm{Al}^{3+}+6 e^{-} \rightarrow 2 \mathrm{Al}(\mathrm{s}), \mathrm{E}_{\mathrm{Al} / \mathrm{Al}^{3+}}^{\circ}=+1.66 \mathrm{~V} \end{aligned} \)
The standard EMF of a cell with feasible redox reaction will be:
1. | +7.09 V | 2. | +0.15 V |
3. | +3.47 V | 4. | –3.47 V |