Question

The following questions relate to the extraction of aluminium by electrolysis:
(c) Explain why is it necessary to renew the anode periodically.

Answer 1

• During the extraction of Aluminium at the anode, the following reaction occurs:

${\text{O}}^{{\text{2}}^{-}}\to \text{O} \text{+} {\text{2e}}^{-}$

$\text{O} \text{+} \text{O}\to {\text{O}}_{\text{2}}$

• $CO$ and $C{O}_2$ are formed when the oxygen generated reacts with the carbon anode.

$\text{C} \text{+} {\text{O}}_{\text{2}}\to {\text{CO}}_{\text{2}}$

• It is depleted due to oxidation at the carbon anode. As a result, carbon rods must be replaced on a regular basis.