What is the role of graphite rods in the electrometallurgy of aluminium?

Explanation

Graphite rods act as anode during electrolytic reduction of alumina. At anode, `O_(2)` gas is produced which react with the carbon of anode (rods) to produce `CO_(2)` gas, so these graphite rods are consumed slowly and need to be replaced from time-to-time.
`Al_(2)O_(3) to 2Al^(3+) +3O^(2-)`
At cathode `Al^(3+) +3e^(-) to Al(l)`
At anode `3O^(2-) to 3[O]+ 6e^(-)`
or `3[O]+ 3[O] to 3O_(2)`
`C+O_(2) to CO_(2)(g)`