Question

The following questions relate to the extraction of aluminium by electrolysis:
(b) Give the equation for the reaction that takes place at the cathode.

Answer 1

• The Hall-Heroult procedure is the electrolytic extraction of Aluminium from pure ore.
• The following reactions occur when electricity is transmitted between the electrodes:

Dissociation of Alumina:

${\text{2Al}}_{\text{2}}{\text{O}}_{\text{3}} \to {\text{4Al}}^{\text{3+}}\text{+} {\text{3O}}_{{\text{2}}^{-}}$

• The reaction that occurs at the cathode has the following equation:

${\text{Al}}^{\text{3+}}\text{+} {\text{3e}}^{-}\to \text{Al}$

Aluminium settles to the bottom of the cell after it is generated in a molten condition at the cathode. It is collected as soon as it is produced. This process produces Aluminium that is $99\%$ pure.