Question

In the commercial electrochemical process for aluminium extraction, the electrolyte used is :

• A. $Al(OH{)}_3$ in $NaOH$ solution
• B. an aqueous solution of $A{l}_2(S{O}_4{)}_3$
• C. a molten mixture of $A{l}_2{O}_3$ and $N{a}_{3}Al{F}_6$
• D. a molten mixture of $AlO\left(OH\right)$ and $Al(OH{)}_3$

Answer 1

The correct option is C a molten mixture of $A{l}_2{O}_3$ and $N{a}_{3}Al{F}_6$

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${}^{\circ }$C and at this temperature when electrolysis is carried out on the fused mass, the metal formed vaporizes, as the boiling point of aluminium is 1800${}^{\circ }$C. These difficulties are overcome by using a mixture containing alumina $\left(A{l}_2{O}_3\right)$, cryolite $\left(N{a}_{3}Al{F}_6\right)$, and fluorspar $\left(Ca{F}_2\right)$.