C6 Electrolysis

• When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes
• Passing an electric current through electrolytes causes the ions to move to the electrodes.
• Positively charged ions move to the negative electrode (cathode)
• Negatively charged ions move to the positive electrode (Anode)
• Solid ionic compounds cannot conduct electricity as the ions are held together by strong electrostatic forces of attraction
• the metal (lead) is produced at the cathode and the non-metal (bromine) is produced at the anode
• Oxidation

  Is

  Loose electrons

  Reduction

  Is

  Gain electrons
• Metals that are more reactive than carbon are extracted using electrolysis
• Aluminium oxide is mixed with cryolite which lowers the melting point therefore reduces the amount of energy needed and saves money
• The anode must be replaced regularly as the oxygen molecules produced at the anode react with graphite(carbon) forming carbon dioxide gas
• The cathode and the anode are both made of graphite (carbon) becuase it is a good conductor of electricity and has a very high melting point.
• Electrolysis is very expensive

  • Melting the compounds such as aluminium oxide requires a lot of energy
  • A lot of energy is required to produce an electric current
• In electrolysis of aqueous solutions, the water molecules spilt forming hydrogen ions and hydroxide ions
• At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen
• Platinum is often used as inert (unreactive) electrodes
• At the positive electrode (anode) oxygen and water is produced unless the solution contains halide ions then the halogen is produced