Explain why it is preferable to use a number of graphite anodes instead of a single electrode during the electrolysis of aluminium.

Explanation

During the electrolysis process, aluminium is deposited at the cathode and oxygen is liberated at the anode. Some of the oxygen reacts with the carbon in the graphite to form carbon dioxide, by consuming the anode slowly. Thus, the anodes have to be replaced periodically or a number of graphite electrode as anodes have to be used.