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General Principles and processes of Isolation of Elements
medium
Aluminium is extracted from alumina $(Al_2O_3)$ by electrolysis of a molten mixture of
A
$Al_2O_3 + Na_3AlF_6 + CaF_2$
B
$Al_2O_3 + KF + Na_3AlF_6$
C
$Al_2O_3 + HF + NaAlF_4$
D
$Al_2O_3 + CaF_2 + NaAlF_4$
Solution
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 aluminum is $1800^{\circ} C$.
These difficulties are overcome by using a mixture containing alumina $\left( Al _2 O _3\right)$, cryolite $\left( Na _3 AlF _6\right)$, and fluorspar $\left( CaF _2\right)$.
Standard 12
Chemistry
