May/June 2026 Paper 43

This question is about the effects of electricity on chemical substances. Concentrated aqueous lithium bromide undergoes electrolysis when electricity is passed through it. The products are: • bromine gas at the anode • hydrogen gas at the cathode. Give the term used to describe any liquid that undergoes electrolysis when electricity is passed through it.

State two properties of a substance that make it suitable to use as an electrode.

Write an ionic half-equation for the formation of bromine at the anode.

Explain why hydrogen gas is produced at the cathode.

Name the type of particle responsible for the transfer of charge in any liquid that undergoes electrolysis.

Name the products formed when electricity is passed through molten lithium bromide.

Bauxite is an ore containing aluminium. Name the compound of aluminium that is present in bauxite.

Aluminium is extracted by electrolysis using cryolite. State two reasons why cryolite is used in this electrolysis.