Question

In the process of electrolysis of water, what is the ratio of the volume of gases collected at cathode and anode? (a) 1:1 (b) 2:1 (c) 3:2 (d) 3:1​

Answer 1

In electrolysis of water:

(a) Name the gas collected at cathode and anode.

(b) Why is volume of one gas collected at one electrode is double of anode?

(c) Why are few drops of dilute H

2

SO

4

added to water?

a) At cathode, H

2

is evolved and at anode O

2

is evolved.

b) At cathode, H

+

ion takes two electron to convert itself into H

2

gas. 2 moles of H

+

gives 1 mole of H

2

.

2H

+

(aq)+2e

−

→H

2

(g)

At anode, OH

−

ion releases two electrons to convert into water and O

2

. 2 mole OH

−

gives 0.5 mole O

2

, i.e why volume of one gas collected at one electron is double of another.

c) Acid is added to make the water conduct electricity as the distilled water is a non-conductor of electricity.