Study of Compounds — Ammonia — Question 3

(a) The diagram below shows the preparation of aqueous ammonia:

Procedure : Water is taken in a container and only a small portion of the mouth of the funnel is dipped in water.

As ammonia dissolves in water at a higher rate than it's production in the flask, the pressure in the funnel above water level decreases for a moment and water rushes into the funnel.

As a result, the rim of the funnel loses it's contact with water. Since, ammonia produced pushes the water down, the funnel comes in contact with water again. In this way, ammonia dissolves in water without back suction of water.

(b) Ammonia being basic in nature reacts chemically with P₂O₅ and CaCl₂

6NH₃ + P₂O₅ + 3H₂O ⟶ 2(NH₄)₃PO₄

4NH₃ + CaCl₂ ⟶ CaCl₂.4NH₃

Hence, P₂O₅ and CaCl₂ are not used to dry NH₃