Electrolysis

• Ionic compounds


  Can conduct electricity when molten or dissolved in water
• Electrolysis


  1. Reactions at positive electrode (anode)

  2. Reactions at negative electrode (cathode)
• Reduction


  Ions gaining electrons
• Oxidation


  Ions losing electrons
• Solid ionic compounds cannot conduct electricity because the ions are locked in place and not free to move
• When an ionic compound is melted or dissolved in water, the forces of attraction are broken and the ions are free to move
• Electrolyte


  Liquids or solutions containing free-moving ions that can conduct electricity
• Cathode


  • Negative electrode, covered with electrons from power supply
• Anode


  • Positive electrode, lacking electrons
• Reactions at cathode (negative electrode)

  Positive ions (e.g. lead ions) gain electrons to form atoms (e.g. lead atoms) - reduction
• Reactions at anode (positive electrode)


  Negative ions (e.g. bromide ions) lose electrons to form atoms (e.g. bromine atoms) - oxidation
• Bromine atoms pair to form bromine molecules
• Electrolysis can be used to extract reactive metals like aluminium