Question

In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?

Answer 1

The balanced chemical equation for the electrolysis of water is:

\[\ce{\underset{Water}{2H2O_{(l)}} ->[Electricity][H2SO4] \underset{Hydrogen}{2H2_{(g)}} + \underset{Oxygen}{O2_{g)}}}\]

It can be observed from the balanced chemical equation that the volumes of hydrogen and oxygen produced during electrolysis are in the ratio 2 : 1. Thus, the volume of hydrogen gas collected in the process is double that of oxygen.