With a neat labelled diagram,describe the extraction of aluminium by Hall - Haroult process.

Explanation

Labelled diagram
Explanation
`2Al_2O_3 + 3C to 4Al + 3CO_2`
OR
Cathod : `Al^(3+) +3e^(-) to Al`
Anode : `C +O^(2+) to CO + 2e^(-0`
OR
`C + 2O^(2-) to CO_2 + 4e^(-)`
Detailed Answer :
Extraction of aluminium from bauxte : .Al. is extracted from Bauxite `(Al_2O_3 . 2H_2O)`.
(i) Concentration of bauxite is done by leaching.
(ii) Electrolytic Reduuction (Hall -Heroult Process ) : Purified bauxite bauxite ore is mixed with cryolite `(Na_3 AlF_6) or CaF_2` Whcih lowers its melting point and increases electrolysis is using graphite rods as anode and carbon lining as cathode.

`The graphite anode is useful for reduction of metal oxide to metal
`2Al_2O_3 + 3C to 4Al +3CO_2`
`Al_2O_3 overset("electrolysis")to 2Al^(3+) + 3CO^(2-)`
At cathode : `Al^(3+) ("melt") +3e^(-) to Al(l)`
At anode : `O^(2-) - 2e^(-) to O`
`O +O to O_2`
`C +O_2 to CO_2`
Graphite rods get burnt forming CO and `CO_2` the aluminium thus obtaned is refined electrolytically using impure Al anode, pure Al as cathode and molten cryolite as electrolyte.