InterviewSolution
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InterviewSolution
| 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» 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. | |