Electrolytic reduction of alumina to aluminum by the Hall-Heroult process is carried outA. In the presence of `NaCl`B. In the presence of fluoriteC. In the presence of cryolite, which forms a melt with lower melting temperatureD. In the presence of cryolite, which forms a melt with higher melting temperature

Electrolytic reduction of alumina to aluminum by the Hall-Heroult proc

1.	Electrolytic reduction of alumina to aluminum by the Hall-Heroult process is carried outA. In the presence of `NaCl`B. In the presence of fluoriteC. In the presence of cryolite, which forms a melt with lower melting temperatureD. In the presence of cryolite, which forms a melt with higher melting temperature
Answer» Correct Answer - C The electrolysis of pure alumina faces some difficulties, Pure alumina is a bad conductor of electricity. The fusion temperature of pure alumina is about `2000^@ C`, and at this temperature, when the electrolysis is carried out on the fused mass, the metal formed vaporises as the boiling point of aluminium is `1800^@ C`. These difficulties are overcome by using a mixture containing alumina, cryolite `(Na_(3)AlF_(6))`, and fluorspar `(CaF_(2))`.

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