Question

Explain how sublimation helps in separating components of a mixture.

Answer 1

Part 1: Sublimation – The process of converting a substance from the solid-state directly into the gaseous state without forming an intermediate liquid state is called sublimation.

Important points about sublimation -

• The substances which undergo sublimation are called sublimable substances.
• The substances that do not undergo sublimation are called non-sublimable substances.
• It is a phase change process in which the solid-state is directly converted into the gaseous state.

Part 2: Process of separation in sublimation-

Let us take a classic example of a mixture of camphor and table salt and understand the separation of components by the process of sublimation.

• Take the mixture into an evaporating dish and cover the dish with an inverted funnel with a cotton plug at the narrow end.
• Now heat the mixture gently and observe the vapours of camphor rising because camphor is sublimable.
• As the vapours rise and get in contact with the cool surface of the funnel it is again converted into solid camphor.
• The table salt remains in the evaporating dish as it is non-sublimable.
• In this way, the mixture of salt and camphor can be separated.