Question

During the electrolysis of acidified water using platinum electrodes, hydrogen is liberated at the ______ and oxygen at the _______.

• A. cathode
• B. anode

Answer 1

During electrolysis of acidified water

1. Reduction of ${\mathrm{H}}^{+}$ion is occur at cathode.

${\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{e}}^{-}\to \mathrm{H}\left(\mathrm{s}\right)$

$\mathrm{H}\left(\mathrm{s}\right)+\mathrm{H}\left(\mathrm{s}\right)\to {\mathrm{H}}_2\left(\mathrm{g}\right)\uparrow$

2. Oxidation of ${\mathrm{OH}}^{-}$ ion is occur at anode.

${\mathrm{OH}}^{-}\left(\mathrm{aq}\right)\to \mathrm{OH}\left(\mathrm{l}\right)+{\mathrm{e}}^{-}$

$4\mathrm{OH}\left(\mathrm{l}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\uparrow$

Hence, during the electrolysis of acidified water using platinum electrodes, hydrogen is liberated at the cathode and oxygen at the anode.