# Transcript

NARRATOR

Aluminium forms solid trihalides when heated with the halogens. Here, we're heating aluminium in a stream of chlorine gas. An exothermic reaction produces white aluminium chloride. Adding aluminium foil to bromine produces aluminium tribromide in a spectacular reaction.

The iodide has the same structure. Here, we mix aluminium with iodine. A drop of water dissolves a little of the iodine and allows the reactants to mix. The heat of the reaction is enough to sublime iodine, hence the purple vapour.