A dilute aqueous solution of $N{a}_{2}S{O}_4$ is electrolysed using platinum electrodes.  The products at the anode and cathode are :

${\mathrm{H}}_2\mathrm{O}$ is more readily reduced at cathode than ${\mathrm{Na}}^{+}$ .  It is also more readily oxidized at anode than ${\mathrm{SO}}_4^{-2}$.  Hence, the electrode reactions are
$\begin{array}{r}2{\mathrm{H}}_2\mathrm{O}+2e^{-}⟶{\mathrm{H}}_2\uparrow +2{\mathrm{OH}}^{-}\left[\text{at cathode }\right]\\ {\mathrm{H}}_2\mathrm{O}⟶\frac{1}{2}{\mathrm{O}}_2\uparrow +2{\mathrm{H}}^{+}+2e^{-}\left[\text{atanode }\right]\end{array}$