The Electrolysis of Bauxite

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The Electrolysis of Bauxite

The method

The bauxite (red-brown solid) - aluminium oxide mixed with impurities - is extracted from the earth.

The extracted aluminium oxide is then treated with alkali, to remove the impurities. This results in a white solid called aluminium oxide or alumina.

The alumina is then transported to huge tanks. The tanks are lined with graphite, this acts as the cathode. Also blocks of graphite hang in the middle of the tank, and acts as anodes.

The alumina is then dissolved in molten cryolite - this lowers the melting point - saves money!

Electricity is passed and electrolysis begins. Electrolysis is the decomposition of a compound using electricity.

When dissolved, the aluminium ions and oxide ions in the alumina can move.

At the cathode:

Here the aluminium ions receive electrons to become atoms again:

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At the anode:

The oxide ions lose electrons to become oxygen molecules, O2:

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Uses of aluminium:

1. Shiny metal - used as jewellery.

2. Low density - used to make aeroplanes and trains.

3. Non-toxic - used in drink cans.