Question

Write the equation for the formation of aluminum at the cathode during the electrolysis of alumina.

Answer 1

Reduction half-reaction

Formation of Aluminum at cathode

• The electrolytic method is used for the reduction of Alumina$\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$ instead of using reducing agents such as Carbon$\left(\mathrm{C}\right)$, Sodium$\left(\mathrm{Na}\right)$ etc.
• The reactivity of Aluminum$\left(\mathrm{Al}\right)$ is greater than Carbon therefore, the oxide of Aluminum undergoes electrolysis to produce free Aluminum.
• At cathode reduction takes place.
• Reduction is the gain of electrons.

Hence, the reaction at the cathode is given by:

${\mathrm{Al}}^{3+}\left(\mathrm{aq}\right)+3{\mathrm{e}}^{-}\to \mathrm{Al}\left(\mathrm{s}\right)$