Question

Aluminum is extracted from its chief ore, bauxite. The ore is first purified and then the metal is extracted from it by electrolytic reduction. Write an equation for the reaction which takes place at the anode during the extraction of aluminum by the electrolytic process.

Answer 1

• The electrolysis of Alumina is: $\underset{\mathrm{Alumina}}{{\mathrm{Al}}_2{\mathrm{O}}_3}\to \underset{\mathrm{Aluminium}\mathrm{ion}}{2{\mathrm{Al}}^{3+}}+\underset{\mathrm{Oxide}\mathrm{ion}}{3{\mathrm{O}}^{2-}}$
• At the anode, the oxide ion is oxidized to nascent oxygen which combines with another nascent oxygen to form oxygen$\left({\mathrm{O}}_2\right)$.

$\begin{array}{rcl}{O}^{2-}& \to & O+2e^{-}\\ O+O& \to & O_2\end{array}$

• The oxygen then combines with carbon to form Carbon monoxide $\left(CO\right)$ and Carbon dioxide $\left(C{O}_2\right)$

$$\begin{gathered} C\left(s\right)+O_2\left(g\right)\to C{O}_2\left(g\right) \\ CarbonOxygenCarbondioxide \\ 2C\left(s\right)+O_2\left(g\right)\to 2CO\left(g\right) \\ CarbonOxygenCarbonmonoxide \end{gathered}$$