Electrolysis of Aluminium Oxide

What can electrolysis be used to do?

To extract metals from their ionic compounds.

What’s electrolysis used for?

If the metal is more reactive than carbon.

Name an example when electrolysis is used:

Aluminium is extracted from aluminium oxide.

What’s step 1 to extract aluminium from aluminium oxide?

The aluminium oxide is mixed with a substance called cryolite, which lowers the melting point.

What’s step 2 to extract aluminium from aluminium oxide?

The mixture is then heated until it’s molten.

What’s step 3 to extract aluminium from aluminium oxide?

Th resulting molten mixture undergoes electrolysis.

Write the symbol equation when aluminium oxide undergoes electrolysis:

2Al₂O₃ → 4Al + 3O₂

What happens at the cathode?

Pure aluminium is formed.

Write the symbol equation when aluminium is formed at the cathode:

Al³⁺ + 3e⁻ → Al

What happens at the anode?

Oxygen is formed.

Write the symbol equation when oxygen is formed at the anode:

2O²⁻ → O₂ + 4e⁻

What’s the anode made of in the elctrolysis of aluminium?

The anode is made of graphite.

What does the graphite do with the oxygen?

It reacts with oxygen to form carbon dioxide and slowly wears away.

What needs to happen for the anode?

It needs to be replaced frequently.