In spite of the addition of cryolite and fluorspar to alumina only Al^(+3)andO^(-2) ions are discharged at their respective electrodes. Justify.

In spite of the addition of cryolite and fluorspar to alumina only Al^

1.	In spite of the addition of cryolite and fluorspar to alumina only Al^(+3)andO^(-2) ions are discharged at their respective electrodes. Justify.
Answer» Solution :Cryolite `(Na_(3)AlF_(6))` and fluorspar `(CaF_(2))` are added to alumina to reduce its melting point. `Al^(+3)` discharges preferentially over `NA^(+)andCa^(+3)` at cathode, because of lower discharge potential of `Al^(+3)` than `Na^(+)andCa^(+)` and at ANODE, `O^(-2)` gets DISCHARGED due to its lower discharge potential than `F^(-)` and is evolved as `O_(2)`, which reacts with carbon anode forming `CO_(2)` gas.