Question

Explain the principle of sublimation.

Answer 1

Definition: The process of conversion of a solid substance directly into its vapours on heating and vapour into solid on cooling is called sublimation.

Principle:

1. This process of separation can be used only if one component of the mixture can sublime.
2. The crude mixture of substances is heated in an evaporating dish covered with a perforated sheet on which an inverted funnel is placed.
3. The vapour of the sublimable substance rises up and condenses on the cooler walls of the funnel upon heating.
4. There is a residue in the evaporating dish left by a constituent substance that did not sublime.
5. The condensed vapours can be scraped off of the inner walls of the funnel.