Question

The following questions relate to the extraction of aluminium by electrolysis: 

1. Name the other aluminium containing compound added to alumina and state its significance. 

2. Give the equation for the reaction that takes place at the cathode. 

3. Explain why is it necessary to renew the anode periodically.

Answer 1

1. Cryolite (Na₃AlF₆)

It reduces the temperature and enhance conductivity. 

2. At Cathode: Al³⁺ + 3e^– → Al 

3. The anode has got to be replaced periodically, as it gets oxidised by the oxygen evolved at the anode.