Ammonia - Higher tier

Physical properties

Ammonia, NH3, is a colourless, pungent gas that is soluble in water and less dense in air.

Test for ammonia

Method: Dip a glass rod in concentrated hydrochloric acid and put this in a sample of the gas.

Result: If ammonia is present, a white ‘smoke’ of ammonium chloride is observed.

Uses of ammonia

Ammonia is used to produce fertilisers by reacting it with acids such as hydrochloric acid and nitric:

NH3 + HCl → NH4Cl

NH3 + HNO3 → NH4NO3

The ammonium salts (ammonium chloride, NH4Cl, and ammonium nitrate, NH4NO3) are very soluble in water, so they can dissolve in soil water and be absorbed by plants.