Ammonia

AMMONIA

Molecular formula: NH3
Molecular weight: 17

Occurrence

 Small quantities of ammonia are found in a place where nitrogenous decay takes place. In combined form it is found in Ammonium chloride and Ammonium sulphate naturally.
Ammonia is a compound and it has molecular weight and molecular formula which has been given above. It forms by combining 1 atom of nitrogen and 3 atoms of hydrogen.

Laboratory preparation of Ammonia gas

Lab preparation of Ammonia gas

Lab preparation of Ammonia gas

 

Ammonia gas is prepared in the laboratory by heating a mixture of ammonium chloride and slaked lime (calcium hydroxide).
            2NH4Cl + Ca (OH)2 = CaCl2 + 2NH3 + 2H2O

Experiment:

Powdered ammonium chloride many be mixed with slaked lime (calcium hydroxide) at the ratio of 2:1. The mixture may be put in a flask or hard glass test tube. Fit a cork at the mouth of the test tube with a delivery tube directing upwards which leads the gas in a jar which is inverted. The gas is lighter than the air and it is collected by downward displacement of air. When the test tube is heated the gas is liberated and collected in a gas jar. To test whether the jar is filled bring a moist red litmus paper. This turns into blue.

Manufacture of Ammonia

Manufacture of ammonia by Haber process

Manufacture of ammonia by Haber process

In industrial scale, ammonia gas is prepared by Haber’s Synthetic process. By laboratory process of preparation of ammonia gas, we cannot fulfill the demand as it is required in the production of nitrogen rich fertilizers such as Ammonium sulphate.
A mixture of one volume of nitrogen and three volumes of hydrogen in a dry state is passed under a pressure of 200 atmospheres through a chamber of packed catalyst consisting of finely divided iron with a little of molybdenum and maintained at about 500◦C . The two gases combine under these conditions to form about 10% of ammonia.
            N2 + 3H2 = 2NH3 + 22,500 cals
The resulting mixture is passed through a coil maintained a very low temperature to condense the ammonia and the remaining uncombined gases are again passed through the catalyst chamber.
In conclusion, the following conditions are required for the preparation of ammonia by Haber’s process.
1.One volume of Nitrogen and three volume of hydrogen flow.
2.Pressure of 200 atmospheres.
3.Temperature of 500◦C .
4.Catalyst, finely divided iron with a little of molybdenum.

Properties of Ammonia Gas

            Physical properties:
1. Ammonia is colorless gas.
2. It has pungent smelling and brings tears into the eyes.
3. It is poisonous.
4. It is lighter than air.
5. It is highly soluble in water.

Chemical properties:

1. It is basic in nature and therefore turns red litmus paper into blue.
2. Ammonia dissolves in water and produces hydroxide (ammonium hydroxide).
Ammonium hydroxide is a base and when it is treated with sulphuric acid, produces ammonium sulphate, a chemical fertilizer.
2NH4OH + H2SO4 = (NH4OH)2 SO4 + 2H2O
3. Ammonia reacts with hydrogen chloride and produces dense white fumes of ammonium chloride. This property of ammonia is the sure test of gas.
NH3 + HCl = NH4Cl

Uses of Ammonia gas

 

Ammonia used in refrigerators.

Ammonia used in refrigerators.

1. In the manufacture of Urea and ammonium sulphate (chemical fertilizer) ammonia is extensively used.
2. Ammonia is used in the manufacture of nitric acid (Ostwald process).
3. It is extensively used in the laboratory as a cleaning agent for removing grease.
4. Ammonia is used in the refrigerators.
5. In the development of blue print of maps ammonia is used.
6. It is also used in the preparation of artificial silk.
5 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *