Which one of the following is used to produce Al by electrolysis?

Options

A. Molten `Al_(2)O_(3)+Na_(3)AlF_(6)` electrolyte carbon coated steel vessel cathode, graphite anode.
B. `Al_(2)O_(3)+PhF_(2)` electrolyte, steel cathode, graphite anode
C. Molten `Al_(2)O_(3)+Na_(3)AlF_(6)` electrolyte, graphite cathode steel anode
D. `Al_(2)O_(3)+H_(2)O` electrolyte graphite cathode, steel anode

Answer

A

Explanation

Molten ` Al_(2)O_(3) + Na_(3) AIF_(6)` as electrolyte , carbon
coated steel vessel cathode , graphite anode is used to produce aluminium (Al) by electrolysis . The process is called Hall's process.
In this process purified alumina is mixed with
` Na AlF_(6) " or " CaF_(2)` (cryolite or fluorspar) , which lowers the melting point of alumina and brings conductivity.
In the electroplytic cell, steel cathode and series of graphite anode are used.
The overall reaction is
` 2Al_(2) O_(3) + 3C to 4Al + 3CO_(2) uarr `
The electrolytic reactions are as follows :
` Al_(2)O_(3) to 2AI^(3+) + 3O^(2-)`
At cathode ` Al^(3+) + 3e^(-) to Al(l)`
At anode ` C (s) + O^(2-) "(melt") to CO (g) + 2e^(-)`
` C (s) + 2O^(2-) ("melt") to CO_(2) (g) + 4e^(-)`
The oxygen liberated at anode reacts with the carbon of anode producing CO and ` CO_(2)`
Hence , option (a) is the correct answer .