Electrolysis of aluminium oxide (molten)

• metals which are less reactive than carbon are extracted by reduction with carbon

  
• Metals which are more reactive than carbon are extracted using electrolysis

  
• Aluminium is extracted from the compound aluminium oxide by electrolysis
• The anode must be replaced regularly. The oxygen molecules produced at the anode react with the graphite ( carbon ), forming carbon dioxide gas
• Aluminium has a very high melting point
• Aluminium production

  1. Mix aluminium oxide with cryolite to lower melting point

  2. Apply an electric current to molten aluminium oxide. 3.electrodes are made from graphite because it is a good conductor of electricity and have high melting point

  4. Aluminium ions Al3+ attracted to cathode, gain 3 electrons to form aluminium atoms 5.Oxide ions O2- attracted to anode, lose 2 electrons to form oxygen atoms

  6. Oxygen atoms at anode pair up to form oxygen molecule O2
• Mixing aluminium oxide with cryolite lowers the melting point, reducing the amount of energy needed and saving money
• electrolysis is very expensive

  • Melting compounds such as aluminium oxide require a great amount of energy
  • alot of energy is required to produce the electric current