Electrolysis to extract metals from oxides

• What process is used to extract reactive metals from their oxides?

  Electrolysis
• Why do metals often exist as oxides?


  Because they react with oxygen in the environment
• What is the purpose of reducing the metal in the oxide?

  To remove the oxygen and isolate the pure metal
• What is the cheap and easy way to reduce metal oxides?

  Reduction with carbon
• Which metals can be reduced using carbon?

  Metals that are less reactive than carbon, like zinc, iron, and copper
• Why is electrolysis more expensive than reduction with carbon?

  Because it requires a lot of energy
• What is the process of electrolysis?

  It separates ionic compounds into their pure elements by passing an electric current through an electrolyte
• What is required for electrolysis to work?

  The ions must be able to move
• Why can't aluminium oxide be used directly in electrolysis?

  Because it is solid and the ions are fixed in place
• What must be done to aluminium oxide before electrolysis can occur?

  It must be melted into a molten state
• What is the melting point of aluminium oxide?

  Over 2000 degrees Celsius
• What mineral is mixed with aluminium oxide to lower its melting point?

  Cryolite
• What is the role of cryolite in the electrolysis process?

  It lowers the melting point of aluminium oxide
• What equipment is needed for the electrolysis of molten aluminium oxide?

  A beaker, two carbon electrodes, and a power source
• What happens to the oxygen ions at the anode during electrolysis?

  They transfer their electrons and are discharged as oxygen atoms
• What is produced at the cathode during the electrolysis of aluminium oxide?

  Molten aluminium metal
• What is the half equation for the reaction at the anode?

  Oxygen ions going to form oxygen atoms plus electrons
• What is the half equation for the reaction at the cathode?

  Aluminium ions combining with electrons to form molten aluminium
• What mnemonic can help remember the difference between oxidation and reduction?

  Oil rig (oxidation is loss, reduction is gain)
• What is the overall equation for the electrolysis reaction of aluminium oxide?


  Aluminium oxide (liquid) goes to form aluminium (liquid) and oxygen (gas)
• What are the steps involved in the electrolysis of aluminium oxide?

  1. Purify aluminium oxide from bauxite
  2. Mix with cryolite to lower melting point
  3. Melt the mixture to create molten aluminium oxide
  4. Set up electrolysis equipment with electrodes and power source
  5. Conduct electrolysis to produce aluminium and oxygen
• What are the roles of the anode and cathode in the electrolysis of aluminium oxide?

  • Anode: Positive electrode where oxidation occurs (oxygen ions lose electrons)
  • Cathode: Negative electrode where reduction occurs (aluminium ions gain electrons)