Electrolysis

• What is electrolysis?

  Splitting ionic compounds using electricity
• Why does the electrolyte need to be molten or aqueous?

  To allow ions to move and conduct electricity.
• What ions go to the cathode?

  Positive ions
• What ions go to anode?

  Negative ions
• What happens to the ions in electrolysis?

  Both discharge and change from ions to atoms
• Al3 +3e- ———>Al


  Reduction-If charges go from whatever to 0
• 2O2- ———>O2 + 4e-


  Oxidation-If it goes from 0 to whatever
• What is added to the electrolyte of aluminium oxide to help with the high melting point of aluminium oxide?

  Add cryolite which would disrupt the lattice and help melt Al3O2 at lower temps which saves energy and money
• Why do you constantly need to change the graphite electrodes?

  Due to the high temps unreactive graphite reacts with the oxygen so overtime CO2 is produced so they constantly need replacing
• Overall electrolysis of aluminium oxide

  Expensive as energy needed for melting electricity and constant change of electrodes
• Electrolysis of solution Rules

  Negative electrode-most reactive metal is made so either hydrogen or copper

  Positive electrode-If halide ions are present then they will be made but if no halide ions oxygen is made via discharge of hydroxide
• Remember this:

  Equation:40H-—->02 +2H20 +4e-