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Aluminium is obtained by
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Electrolysing $\mathrm{Al}_2 \mathrm{O}_3$ dissolved in $\mathrm{Na}_3 \mathrm{AlF}_6$
Aluminium is obtained by electrolising alumina dissolved in cryolite $\left(\mathrm{Na}_3 \mathrm{AlF}_6\right)$
$\begin{aligned} & 4 \mathrm{Na}_3 \mathrm{AlF}_6 \leftrightharpoons 12 \mathrm{Na}^{+}+4 \mathrm{Al}^{3+}+12 \mathrm{~F}^{-} \\ & 4 \mathrm{Al}^{3+}+12 \mathrm{e}^{-} \rightarrow 4 \mathrm{Al} \text { (at cathode) } \\ & 12 \mathrm{~F}^{-} \rightarrow 6 \mathrm{~F}_2+12 \mathrm{e}^{-} \text {(at anode) } \\ & 2 \mathrm{Al}_2 \mathrm{O}_3+6 \mathrm{~F}_2 \rightarrow \mathrm{AlF}_3+3 \mathrm{O}_2\end{aligned}$
$\begin{aligned} & 4 \mathrm{Na}_3 \mathrm{AlF}_6 \leftrightharpoons 12 \mathrm{Na}^{+}+4 \mathrm{Al}^{3+}+12 \mathrm{~F}^{-} \\ & 4 \mathrm{Al}^{3+}+12 \mathrm{e}^{-} \rightarrow 4 \mathrm{Al} \text { (at cathode) } \\ & 12 \mathrm{~F}^{-} \rightarrow 6 \mathrm{~F}_2+12 \mathrm{e}^{-} \text {(at anode) } \\ & 2 \mathrm{Al}_2 \mathrm{O}_3+6 \mathrm{~F}_2 \rightarrow \mathrm{AlF}_3+3 \mathrm{O}_2\end{aligned}$
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