Electrolysis

• What is electrolysis?


  Process of using electricity to extract elements from a compound
• What is the name of the positive electrode?

  Anode
• What is the name of the negative electrode?

  Cathode
• What is an electrolyte?


  Liquid or solution that contains ions and so can conducts electricity
• Where are metals formed during electrolysis?


  At the cathode
• Where are non-metals formed during electrolysis?


  At the anode
• How can ionic substances be electrolysed?

  By melting or dissolving them, and then passing a direct current through them
• Why can solid ionic substances not be electrolysed?


  They do not conduct electricity, or the ions cannot move
• In the electrolysis of solutions, when is the metal not produced at the cathode?


  When the metal is more reactive than hydrogen
• In the electrolysis of a metal halide solution, what is produced at the anode?


  Halogen
• In the electrolysis of a metal sulfate solution, what is produced at the anode?


  Oxygen
• What is the half equation for the ionisation of water?

  H2O (l) <--- H+(aq) + OH- (aq)
• What metals are extracted from ionic compounds by using electrolysis?


  Metals that are more reactive than carbon
• In the electrolysis of aluminium oxide, why is the aluminium oxide mixed with cryolite?


  To lower the melting point
• In the electrolysis of aluminium oxide, what are the anodes made of?


  Graphite
• In the electrolysis of aluminium oxide, why do the anodes need to be replaced?


  They react with the oxygen being formed