Preparation of Ammonia

By Heating any Ammonium Salt with an Alkali

In the laboratory, ammonia is usually prepared by heating a mixture of ammonium chloride and slaked lime in the ratio of 2 : 3 by mass. The arrangement of the apparatus is shown in the figure 6.2. As ammonia is lighter than air, it is collected by the downward displacement of air.

By the Action of Water on Metallic Nitrides

Take magnesium nitride, aluminium nitride or calcium nitride in a conical flask as shown in figure 6.3. Add hot water to it through the thistle funnel. The respective hydroxide and ammonia are formed.

Drying of Ammonia

The drying agent used for ammonia is quick lime. Other drying agents such as concentrated sulphuric acid or phosphorus (V) oxide or fused calcium chloride cannot dry an alkaline gas like ammonia.

Sulphuric acid and phosphorus (V) oxide are both acidic. They react with ammonia, forming their respective ammonium salt.

Fused calcium also cannot be used as it absorbs ammonia and forms additional products such as CaCl₂.4NH₃ and CaCl₂.8NH₃.