Electrochemistry

The values of conductivity of some materials at 298.15 K in S m-1 are 2.1 103, 1.0 10-16, 1.2 10, 3.91, 1.5 10-2, 1 10-7, 1.0 103. The number of conductors among the materials is .

Reduction potential of ions are given below: [figure] The correct order of their oxidising power is :

1. IO4- > BrO4- > ClO4-
2. BrO4- > ClO4- > IO4-
3. ClO4- > IO4- > BrO4-
4. BrO4- > IO4- > ClO4-

The mass of zinc produced by the electrolysis of zinc sulphate solution with a steady current of 0.015 A for 15 minutes is 10-4 g. (Atomic mass of zinc = 65.4 amu)

A constant current was passed through a solution of AuCl4- ion between gold electrodes. After a period of 10.0 minutes, the increase in mass of cathode was 1.314 g. The total charge passed through the solution is 10-2 F. (Given atomic mass of Au = 197)

The mass of silver (Molar mass of Ag : 108 g mol-1) displaced by a quantity of electricity which displaces 5600 mL of O2 at S.T.P. will be g.

Which of the following statements is not correct about rusting of iron?

1. Rusting of iron is envisaged as setting up of electrochemical cell on the surface of iron object.
2. Dissolved acidic oxides SO2, NO2 in water act as catalyst in the process of rusting.
3. Coating of iron surface by tin prevents rusting, even if the tin coating is peeling off.
4. When pH lies above 9 or 10, rusting of iron does not take place.

The hydrogen electrode is dipped in a solution of pH = 3 at 25 . The potential of the electrode will be − 10-2 V. ( 2.303RTF = 0.059 V )