Question

In order to obtain $1$ tonne of aluminum, the following inputs are required: four tonnes of bauxite, $150Kg$ of sodium hydroxide, and $600Kg$ of graphite. The aluminum compound in bauxite is aluminum oxide and the main impurity is iron $\left(III\right)$ oxide. Aluminum is obtained by the electrolysis of aluminum oxide dissolved in cryolite.

When bauxite is treated with sodium hydroxide solution what happens to:

aluminum oxide?

Answer 1

• Bauxite($\mathit{A}{\mathit{l}}_{\mathbf{2}}{\mathit{O}}_{\mathbf{3}}\mathbf{.}\mathbf{2}{\mathit{H}}_{\mathbf{2}}\mathit{O}$) is the ore of Aluminum.
• Bauxite contains about $60\%$ of Aluminum Oxide$\mathit{A}{\mathit{l}}_{\mathbf{2}}{\mathit{O}}_{\mathbf{3}}$ and other oxides such as Iron, Silicon, and Titanium.
• In order to remove impurities from bauxite, the ore is treated with Sodium hydroxide and it will dissolve the bauxite and forms Sodium aluminate.
• The reaction is $\underset{Bauxite}{A{l}_2{O}_3.2H_{2}O\left(s\right)}+\underset{Sodiumhydroxide}{2NaOH\left(l\right)}\to \underset{SodiumAluminate}{2NaAl{O}_2\left(aq\right)}+\underset{\mathrm{Water}}{3H_{2}O\left(l\right)}$

Hence, the Aluminum oxide is converted to Sodium aluminate by the action of Sodium Hydroxide.