Thursday, September 3, 2020


 Ammonia has molecular weight of 17 amu. It is formed by the combination of nitrogen and hydrogen gases. For the first time ammonia was prepared by Lavoisier by heating the mixture of ammonium chloride and calcium hydroxide. Some soil bacteria create natural ammonia underground. Ammonia is also formed when protein rich materials decay in absence of oxygen. In the form of compounds it is found on ammonium chloride and ammonium sulphate.

Ammonia was first discovered by the ancient Egyptians, the Egyptians found this chemical compound by accident as it occurs naturally in cracks near volcanoes, and when it is warmed it decomposes into the pungent ammonia. This was then used in their religious rites. The worshippers of the Egyptian god Amun - known as the Ammonians named this chemical compound 'Ammonia'.

Laboratory Preparation of Ammonia gas: As shown in fig below, ammonia is prepared by heating ammonium chloride and calcium hydroxide in 2:1 ratio on hard glass test tube.

2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3

As shown in fig, when delivery tube is heated ammonia gas is formed and passes through delivery tube. To collect fully dry gas it is passed through calcium oxide tower. Via another delivery tube gas is collected on inverted gas jar as it is lighter than air.

Manufacturing of Ammonia gas: In large scale ammonia is obtained by reacting hydrogen and nitrogen in 1:3 ratio under the temperature of 500oC, pressure of 200 to 300 atm on the presence of iron as catalyst and molybdenum as promoter. This process is also called Haber’s Process.

 N2 + 3H2 2NH3

Physical Properties of Ammonia

1.  It is colorless gas with strong smell and tears on eye

2. It is lighter than air

3. It is highly soluble in water

4. It forms alkali when dissolved in water

5. It is neither combustible nor supports combustion

Read Chemical Properties and Uses of ammonia in next post.


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