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Question: Answered & Verified by Expert
Aluminium is extracted from alumina $\left(\mathrm{Al}_2 \mathrm{O}_3\right)$ by electrolysis of a molten mixture of
ChemistryGeneral Principles and Processes of Isolation of MetalsNEETNEET 2012 (Screening)
Options:
  • A $\mathrm{Al}_2 \mathrm{O}_3+\mathrm{HF}+\mathrm{NaAlF}_4$
  • B $\mathrm{Al}_2 \mathrm{O}_3+\mathrm{CaF}_2+\mathrm{NaAlF}_4$
  • C $\mathrm{Al}_2 \mathrm{O}_3+\mathrm{Na}_3 \mathrm{AlF}_6+\mathrm{CaF}_2$
  • D $\mathrm{Al}_2 \mathrm{O}_3+\mathrm{KF}+\mathrm{Na}_3 \mathrm{AlF}_6$
Solution:
1900 Upvotes Verified Answer
The correct answer is: $\mathrm{Al}_2 \mathrm{O}_3+\mathrm{Na}_3 \mathrm{AlF}_6+\mathrm{CaF}_2$
Alumina, $\mathrm{Al}_2 \mathrm{O}_3$, is a bad conductor of electricity and has very high melting point, so before subjecting to electrolysis, it is mixed with fluorspar $\left(\mathrm{CaF}_2\right)$ and cryolite $\left(\mathrm{Na}_3 \mathrm{AlF}_6\right)$, which lower its melting point and make it more conducting.

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