Question

Describe an experiment to demonstrate the process of sublimation?

Answer 1

Sublimation:

• Sublimation is the process in which a solid substance is directly converted into the gaseous state without passing through the liquid state.
• This process is used to separate a mixture containing a constituent that sublimes.
• It is used to separate the substances such as ammonium chloride, iodine, naphthalene, etc.

Experiment:

• Take a mixture of ammonium chloride$\left({\mathrm{NH}}_4\mathrm{Cl}\right)$ and common salt$\left(\mathrm{NaCl}\right)$ in an evaporating dish and cover it with an inverting glass funnel.
• Lock the end of the stem of the funnel with cotton wool to prevent the ammonium chloride from escaping into the atmosphere.
• Now heat the mixture gently.
• As the ammonium chloride is sublime after heating, it will directly convert into vapour.
• This vapour will again condense at the upper colder part of the funnel to form solid ammonium chloride.
• In this way, the mixture of ammonium chloride and common salt can be separated by the sublimation method.