Question

In the electrolysis of water-(3 marks)
(i) Name the gas collected at the cathode and respectively.
(ii) Why is the volume of gas collected at one electrode double than that at the other
(iii) Given distinguishing tests for the gases evolued.

Answer 1

1. hydrogen at cathode and oxygen at anode
2. when one molecule of water i.e H20 is dissociate it forms two molecule of hydrogen H2 and one molecule of oxygen 02.hence volume of one electode is double than other.

Explanation:

At the cathode (-) water is reduced:

H2O(l)+e→1/2H2(g)+OH-(aq).

At the anode (+) water is oxidized:

H2O(l)→1/2O2(g)+2H+(aq)+2e