During the electrolysis of cryolite, aluminium and fluorine are formed in ........ molar ratio :
During the electrolysis of cryolite, aluminium and fluorine are formed in ........ molar ratio :
$1: 2$
$2: 3$
$1: 1$
$1: 3$
Solution
Electrolysis of cryolite can be explained as
$\mathrm{Na}_3 \mathrm{AlF}_6 \rightleftharpoons 3 \mathrm{NaF}+\mathrm{AlF}_3$
$4 \mathrm{AlF}_3 \rightleftharpoons 4 \mathrm{Al}^{3+}+12 \mathrm{~F}^{-}$
$\begin{array}{cc}+12 e^{-} \downarrow & \downarrow-12 e^{-} \\ 4 \mathrm{Al} & 6 \mathrm{~F}_2\end{array}$
(At cathode) (At anode)
So, the molar ratio of $\mathrm{Al}$ and $\mathrm{F}_2$ is $4: 6=2: 3$.