Question

Answer in one word: Name the product formed at the anode during the electrolysis of acidified water using platinum electrodes.

Answer 1

Electrolysis is the decomposition of the compound by passing electric current n its aqueous or molten state.

1. Pure water do not electrolyzed because it contains water molecules that do not dissociate into ions.

2. By adding an acid such as sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ in water. It helps in the ionization of water.

Chemical Equation: This acidified water dissociates into ions. ${\mathrm{H}}^{+},{\mathrm{OH}}^{-},{\mathrm{SO}}_4^{2-}$ions are present in the solution.

$$\begin{gathered} {\mathrm{H}}_2{\mathrm{SO}}_4\rightleftharpoons 2{\mathrm{H}}^{+}+{\mathrm{SO}}_4^{2-} \\ \mathrm{sulphuric}\mathrm{hydrogen}\mathrm{sulphate} \\ \mathrm{acid}\mathrm{ion}\mathrm{ion} \end{gathered}$$

$$\begin{gathered} {\mathrm{H}}_2\mathrm{O}\rightleftharpoons {\mathrm{H}}^{+}+{\mathrm{OH}}^{-} \\ \mathrm{water}\mathrm{hydroxide}\mathrm{ion} \end{gathered}$$

At anode, ${\mathrm{OH}}^{-}$ ions are negatively charged, moves towards the anode which is a positively charged electrode. ${\mathrm{OH}}^{-}$ ions are discharged at anode.

Reaction :

$$\begin{gathered} {\mathrm{OH}}^{-}\to \mathrm{OH}+{\mathrm{e}}^{-} \\ 2\mathrm{OH}+2\mathrm{OH}\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2\uparrow \end{gathered}$$

Hence, during electrolysis of acidified water, oxygen is evolved at anode.