Question

Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?

Answer 1

Dihydrogen is prepared by the electrolysis of acidified or alkaline water using platinum electrodes. Generally, 15 - 20% of an acid $\left(H_{2}S{O}_4\right)$ or a base (NaOH) is used.
Reduction of water occurs at the cathode as:
$2H_{2}O+2e^{-}\to 2H_2+2O{H}^{-}$
At the anode, oxidation of $O{H}^{-}$ ions takes place as:
$2O{H}^{-}\to H_{2}O+\frac{1}{2}{O}_2+2e^{-}$
$\therefore$ Net reaction can be represented as:
$H_2{O}_{\left(l\right)}\to H_{2\left(g\right)}+\frac{1}{2}{O}_{2\left(g\right)}$
Electrical conductivity of pure water is very low owing to the absence of ions in it. Therefore, electrolysis of pure water also takes place at a low rate. If an electrolyte such as an acid or a base is added to the process, the rate of electrolysis increases. The addition of the electolyte to take place.