Electrolysis of Aluminium Oxide

• Electrolysis


  Used to extract some metals
• Extracting aluminium by electrolysis

  1. Mix aluminium oxide with compound cryolite to lower melting point

  2. Apply electric current to molten aluminium oxide

  3. Aluminium ions attracted to cathode and gain 3 electrons to form aluminium atoms

  4. Oxide ions attracted to anode and lose 2 electrons to form oxygen atoms
• Cathode reaction


  • Aluminium ions (Al3+) gain 3 electrons to form aluminium atoms
• Anode reaction


  • Oxide ions (O2-) lose 2 electrons to form oxygen atoms
• Oxygen atoms formed at anode pair up to form oxygen molecules (O2)
• Anode must be replaced regularly as the oxygen reacts with the graphite to form carbon dioxide
• Producing metals by electrolysis is very expensive due to the high energy required to melt the compounds and produce the electric current
• Aluminium oxide

  A compound with the chemical formula Al2O3, used in the electrolysis process to extract aluminium
• Cryolite

  A compound with the chemical formula Na3AlF6, used to lower the melting point of aluminium oxide in the electrolysis process
• Electrolysis


  The process of using an electric current to drive a chemical reaction
• Cathode


  The negatively charged electrode in an electrolytic cell, where aluminium ions gain electrons and become neutral atoms
• Anode


  The positively charged electrode in an electrolytic cell, where oxide ions lose electrons and form oxygen atoms
• Aluminium ions


  Positively charged ions with the chemical symbol Al3+, which are attracted to the cathode in the electrolysis process
• Oxide ions


  Negatively charged ions with the chemical symbol O2-, which are attracted to the anode in the electrolysis process
• Oxygen atoms


  Neutral atoms formed when oxide ions lose two electrons at the anode during the electrolysis process