Question

In the commerdal electrochemical process for aluminium extraction, the electrolyte used is

• A. $Al(OH)_3$ in $NaOH$ solution
• B. an aqueous solution of $ Al_2(SO_4)_3$
• C. a molten mixture of $Al_2O_3$ and $Na_3AlF_6$
• D. a molten mixture of $Al_2O_3$ and $Al(OH)_3$

Answer 1

Answer: (C)

For commercial extraction of aluminium, we use a molten mixture of $Al_2O_3$ and $Na_3AlF_6$ (cryolite).
$ Al_2O_3$ is an electrolyte and $Na_3AlF_6$ is added to decrease the melting point of $Al_2O_3$ and increase the conductivity.