Question

Is sublimation a chemical change or physical change? What about sublimation of ammonium chloride?

Answer 1

The term sublimation refers to a physical change of state and is used to describe the transformation of a solid to a gas . \

Dissociation on heating of solid ammonium chloride into hydrogen chloride and ammonia is not sublimation but a chemical reaction.
They sublime when heated; the substance changes directly from being solid to gas. The gas does not consist of ammonium chloride molecules but ammonia and hydrogen chloride. This shows that the salt decomposes easily.