Understand C.4.3.2 and C 4.3.3 Using electrolysis to extract metals (Aluminium)
Channel: Hands on Chemistry
Date: 2020-07-17

AQA Specification Notes:

C 4.3.2 Electrolysis of molten ionic compounds

When a simple ionic compound (eg lead bromide) is electrolysed in the molten state using inert electrodes, the metal (lead) is produced at the cathode and the non-metal (bromine) is produced at the anode.

Students should be able to predict the products of the electrolysis of
binary ionic compounds in the molten state.

C 4.3.3 Using electrolysis to extract metals

Metals can be extracted from molten compounds using electrolysis.
Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon. Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current.
Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).

Students should be able to:
• explain why a mixture is used as the electrolyte
• explain why the positive electrode must be continually replaced.