Electrolysis

• During electrolysis. an electric current is passed through an electrolyte. The ions move towards the electrodes, where they react, and the compound decomposes
• The positive ions move towards the cathode and gain electrons (reduced)
• Negative ions in the electrolyte will move towards the anode and 10 se electrons (oxidised)
• As ions gain or lose electrons, they form the uncharged element and are discharged from the electrolyte
• Electrolysis of molten ionic solids forms elements

  • An ionic solid can't be electrolysed because the ions are in fixed positions and can't move
  • Molten ionic compounds can be electrolyted because the ions can move freely and conduct electricity
• Extracting metals from their ores


  Using electrolysis
• Aluminum


  Extracted from the ore bauxite by electrolysis
• Aluminum oxide


  • Has a very high melting temperature
  • Mixed with Cryolite to lower the Melting point
• Molten mixture


  Contains free ions so it'll conduct electricity
• Electrolysis of molten aluminum oxide

  1. Positive Al 3+ ions are attracted to the negative electrode

  2. They pick up three electrons and turn into neutral aluminium atoms

  3. Neutral aluminium atoms sink to the bottom of the electrolysis tank
• Electrolysis of molten aluminum oxide

  1. Negative 02- ions are attracted to the positive electrode

  2. They lose two electrons

  3. Neutral oxygen atoms combine to form 0-2 Molecules