(i) Name the solution used to react with Bauxite as a first step in obtaining pure aluminium oxide, in the Baeyer's process.

(ii) Write the equation for the reaction where the aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide.

(iii) Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.

(iv) Write the equation for the reaction that occurs at the cathode during the extraction of aluminium by electrolysis.

(v) Explain why it is preferable to use a number of graphite electrodes as anode instead of a single electrode, during the above electrolysis.

(i) Sodium hydroxide

(ii) Conversion of Al(OH)₃ - to pure alumina - heat on Al(OH)₃

$\underset{\text{[aluminium hydroxide]}}{\text{2Al(OH)}$3} \xrightarrow{1100\degree\text{C}} \underset{\text{[pure alumina]}}{\text{Al}2\text{O}3} + \text{3H}2\text{O}

(iii) Cryolite (Na₃AlF₆)

(iv) 2Al³⁺ + 6e^- ⟶ 2Al

(v) The oxygen evolved at the anode escapes as a gas or reacts with the carbon anode. The carbon anode is thus oxidized to carbon monoxide which either burns giving carbon dioxide or escapes out through an outlet. [2C + O₂ ⟶ 2CO; 2CO + O₂ ⟶ 2CO₂] The carbon anode is hence consumed and renewed periodically after a certain period of usage. It is therefore preferable to use a number of graphite electrodes as anode instead of a single electrode.