The Extraction of Aluminium
Aluminium is extracted from an ore called bauxite, which is impure aluminium oxide. Aluminium ions are attracted to the cathode and are reduced to aluminium:
Al3+ + 3e– -> Al
Oxide ions are attracted to the anode and lose electrons to form oxygen gas:
2O2- -> O2 + 4e–
There are a few things to keep in mind:
- Melting aluminium oxide requires extremely high temperatures. Instead, it is dissolved in an aluminium compound called cryolite.
- Because of high temperatures, the carbon anodes will burn with oxygen to form carbon dioxide. This means the anodes have to be replaced regularly.
- The cost of electricity is also a major factor – the cell has currents up to 100 000A so it is expensive.
Uses of aluminium include:
| Use | Property of Aluminium That Makes This Useful |
| To make aircraft carriers | § Resists corrosion due to its aluminium oxide coat
§ Has low density § Strong |
| Saucepans | § Aluminium has a shiny appearance
§ It is a good conductor of heat § It resists corrosion § It has a low density |