Extracting Metals - Electrolysis
Chemistry: Edexcel IGCSE, topic 11.1.2
Electrolysis - Extracting Metals
Electrolysis is used to extract reactive metals from molten ores (melted materials containing metals). Electrolysis is used to extract metals such as aluminium, which are higher in the reactivity series than carbon.
Process
- Powdered aluminium ore (Al2O3) is first mixed with another aluminium salt called cryolite.
- This mixture has a lower melting point than pure Al2O3. This makes it cheaper as less energy is needed to melt the powder.
- Once molten, a large voltage is applied.
What happens at the cathode?
- The aluminium is formed at the cathode.
What happens at the anode?
- Oxygen forms at the carbon anode. The carbon and oxygen react to give carbon dioxide.
- The anode is usually made of carbon because it is a good conductor and is cheap.
What are the disadvantages of electrolysis?
- Lots of energy is needed to:
- Melt the solid ionic compound to allow the ions to flow.
- Produce the electrical current.
- All this energy costs money, and a lot of it!
Test yourself on Extracting Metals - Electrolysis
What aspects of using electrolysis to extract metals need lots of energy?
Why does electrolysis cost a lot of money to carry out?
Why is the anode used in electrolysis usually made of carbon?
Electrolysis of Aluminium
What's the advantage of mixing powdered aluminium ore with cryolite?