draw a neat labelled diagram electrolytic reduction explain why cryolite and fluorspar mixture
Answers
Answer:
The electrolysis of alumina is carried out in a steel tank lined inside with graphite. The graphite lining serves as
cathode. Anode is also made of graphite rods hanging in the molten mass.
The electrolyte consists of alumina dissolved in fused Cryolite(Na3AlF6) and Fluorspar(CaF2).
Cryolite lowers the melting point of alumina to 9500C and fluorspar increases the fluidity of the mass so that
the liberated aluminum metal may sink at the bottom of the cell.
When electric current is passed through this mixture, the aluminum is collected at the cathode in molten state
and sinks at the bottom and is tapped off.
Ionization of Alumina:
2Al2O3 → 6O-2 + 4Al+3
Reaction at Cathode:
4Al+3 + 12e- → 4Al
Reaction at Anode:
6O-2 → 3O2 + 12e-
C + O2 → C