Electro Chemistry Three Marks Questions

12th Standard EM

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 50
10 x 5 = 50
1.  Calculate the standard emf of the cell: Cd|Cd2+||Cu2+|Cu and determine the cell reaction.
The standard reduction potentials of Cu2+|Cu and Cd2+|Cd  are 0.34V and -0.40 volts
respectively. Predict the feasibility of the cell reaction.

2. In fuel cell H2and O2 react to produce electricity. In the process, H2 gas is oxidised at the
anode and O2 at cathode. If 44.8 litre of H2 at 250C and also pressure reacts in 10 minutes,
what is average current produced? If the entire current is used for electro deposition of Cu
from Cu2+ , how many grams of deposited?

3. The same amount of electricity was passed through two separate electrolytic cells containing solutions of nickel nitrate and chromium nitrate respectively. If 2.935g of Ni was deposited in the first cell. The amount of Cr deposited in the another cell? Give : molar mass of Nickel and chromium are 58.74 and 52gm-1 respectively.

4. 0.1M copper sulphate solution in which copper electrode is dipped at 250C . Calculate the electrode potential of copper. [Given: E0Cu2+|Cu=0.34].

5. For the cell Mg (s) Mg2+(aq)||Ag2+(aq)|Ag(s), calculate the equilibrium constant at 250C and maximum work that can be obtained during operation of cell. Given : $E^{0}_{Mg^{2+}|Mg}$=-237V and $E^{0}|_{Ag^{2+}|Ag}$=0.80V.

6. 8.2$\times$1012 litres of water is available in a lake. A power reactor using the electrolysis of
water in the lake produces electricity at the rate of 2$\times$106 Cs−1 at an appropriate voltage.
How many years would it like to completely electrolyse the water in the lake. Assume that
there is no loss of water except due to electrolysis.

7. Derive an expression for Nernst equation

8. Write a note on sacrificial protection.

9. Explain the function of H2 - O2 fuel cell.

10. Ionic conductance at infinite dilution of Al3+ and SO4 2- are 189 and 160 mho cm2 equiv-1. Calculate the equivalent and molar conductance of the electrolyte Al2 (SO4)3 at infinite dilution.