5.2 describe and explain the extraction of aluminium from purified aluminium oxide by electrolysis, including: the use of molten cryolite as a solvent and to decrease the required operating temperature, the need to replace electrodes, the cost of electricity as a major factor

5.2 •aluminium oxide is dissolved in molten cryolite to reduce the temperature, making it cheaper and easier to extract

      

      •the oxygen burns the positive electrode away quickly and so need to be frequently replaced 

      •the electrodes are made of graphite, a good conductor of electricity, reducing the amount of electricity needed