Describe an experiment to demonstrate the process of sublimation.

The process of sublimation is demonstrated by the following experiment —

1. Take some ammonium chloride and powder it.
2. Keep the powder in a china dish.
3. Cover the china dish with an inverted funnel as shown in the figure.
4. Close the end of the funnel with a piece of cotton.
5. Place the china dish on a wire mesh kept on a tripod stand and heat it by a burner.

Observations — We will observe that vapours of ammonium chloride are formed in the inverted funnel above the dish. These vapours upon rising, get cooled and change to solid ammonium chloride which gets deposited on the inner walls of the inverted funnel.

Conclusion — Ammonium chloride on heating changes directly into gaseous state and when these vapours are cooled they get converted back into solid state. This demonstrates the process of sublimation.