Question

Explain the change of state from solid to vapour on the basis of molecular theory.

Answer 1

Sublimation:-

1. Naphthalene balls kept inside wardrobes and cupboards become smaller and smaller and finally disappear because some substances like naphthalene, iodine, camphor and ammonium chloride change directly from solid to vapour on heating.
2. They do not pass through the intermediate liquid state.
3. The process of a solid directly changing to vapour on heating without passing through the liquid state is called sublimation.
4. Substances that undergo sublimation are called sublimates.
5. On cooling, these vapours condense into solids.