Question

4. Describe an experiment for separation of pure ammonium chloride from a mixture of common salt and ammonium chloride.

Answer 1

Step 1: Mixture of common salt and ammonium chloride

• By sublimation, a mixture of common salt (NaCl) and ammonium chloride (NH₄Cl) can be separated.
• Sublimation is the transition of a substance from the solid phase to the gaseous phase without changing into the liquid phase.
• We used this method when a mixture consists of two or more solids, in which one of the solids sublimes on heating.
• In a mixture of ammonium chloride and common salt, ammonium chloride can sublime.

Step 2: Experiment for separation of pure ammonium chloride from a mixture of common salt and ammonium chloride

The steps for performing the sublimation process are following:

1. A mixture of common salt and ammonium chloride should be taken in a china dish.
2. Over a tripod stand place an iron pan containing the sand. Place a wire gauze under the sand pan.
3. The mixture should be taken in an inverted funnel covered with a cotton wool plug.
4. Heat the mixture over a low Bunsen flame.
5. After some time, white fumes are seen to rise in a funnel. These fumes are of ammonium chloride.
6. They gradually settle on the upper walls of the funnel to form a fine white powder.
7. Now, remove the funnel and scrap ammonium chloride from its walls.
8. Repeat the process. Ammonium chloride will separate completely.