Identify two other applications of aluminium apart from aircraft construction. Name the ore from which aluminium is extracted, and the impurity removed during purification. Label the anode, cathode an

3(b)(i) Duralumin is an alloy of aluminium that is lightweight and strong. These properties are essential for aircraft construction, including window frames, to ensure structural integrity while minimizing weight for fuel efficiency.

3(b)(ii) Apart from aircraft construction, two other applications of aluminium are:

• Cooking utensils
• Food packaging (e.g., aluminium foil)

B. The extraction of aluminium from its ore takes place in two stages, purification stage and electrolysis stage. The diagram below shows the set up for the electrolysis stage.

i) The ore from which aluminium is extracted is bauxite.

$$\boxed{\text{Bauxite}}$$

ii) The impurity removed at the purification stage is iron(III) oxide.

$$\boxed{\text{Fe}_2\text{O}_3}$$

iii) Label on the diagram each of the following:

• Anode: The vertical carbon rods suspended in the electrolyte.
• Cathode: The carbon lining of the steel tank, which forms the bottom and sides of the cell.
• Region containing electrolyte: The molten mixture of aluminium oxide and cryolite that fills the cell, surrounding the anodes.

iv) The melting point of aluminium oxide is $2054^\circ\text{C}$, but electrolysis is carried out between $800^\circ\text{C}$ - $1000^\circ\text{C}$.
1. Electrolysis is not carried out at $2054^\circ\text{C}$ because maintaining such a high temperature would require excessive energy, making the process economically unfeasible and technically challenging.
2. To lower the temperature, cryolite ($\text{Na}_3\text{AlF}_6$) is added to the aluminium oxide. Cryolite acts as a solvent and lowers the melting point of the mixture.

v) Two properties that make aluminium be collected as shown in the diagram (at the bottom of the cell) are:

• Molten aluminium is denser than the electrolyte.
• Aluminium is in a molten (liquid) state at the operating temperature ($800^\circ\text{C}$ - $1000^\circ\text{C}$).

c) Two properties of aluminium that make it suitable for use in making overhead electric cables are:

• It is a good electrical conductor.
• It has a low density, making the cables lightweight and easier to support.