Question

Write equations for the reactions taking place at cathode and at anode during the electrolysis of:

1. Acidified nickel sulphate solution with nickel electrode.
2. Acidulated water with inert electrode.

[2 marks]

Answer 1

1. Acidified nickel sulphate solution with nickel electrode.

At cathode:
${\mathrm{Ni}}^{2+}\left(\mathrm{aq}\right)+2e^{-}\to \mathrm{Ni}\left(s\right)$ [0.5 marks]

At anode:

$\mathrm{Ni}\left(s\right)\to {\mathrm{Ni}}^{2+}\left(\mathrm{aq}\right)+2e^{-}$ [0.5 marks]

2. Acidulated water with inert electrode.

At cathode:
$2H^{+}\left(\mathrm{aq}\right)+2e^{-}\to H_2\left(g\right)$ [0.5 marks]

At anode:

${\mathrm{OH}}^{-}\left(\mathrm{aq}\right)\to \mathrm{OH}\left(\mathrm{aq}\right)+2e^{-}4\mathrm{OH}\left(\mathrm{aq}\right)\to 2H_{2}O\left(l\right)+O_2\left(g\right)$ [0.5 marks]