Ammonia, NH3, is an important raw material in the manufacture of fertilisers. Some ammonia is converted into nitric acid which itself is used in the manufacture of fertilisers and explosives. Ammonia is also a useful ingredient in some cleaning fluids.

Ammonia plant at night.
An ammonia production plant

Ammonia is a vital route by which nitrogen in the air can be made available to plants to enable them to build protein molecules. Plants cannot use nitrogen directly from the air. They need nitrogen compounds, dissolved in water, which they absorb through their roots.

Without synthetic, ammonia-based fertilisers, the world would be unable to grow enough food to feed its population.

Tests for ammonia and ammonium ions

Ammonia, NH3, is an alkaline gas and so turns damp red litmus paper blue.

Test for ammonia gas: turns damp red litmus paper blue.

Ammonium ions (NH4+) – found in ammonium compounds such as ammonium chloride, ammonium nitrate and ammonium sulfate – can be identified by heating a solution of the ions with sodium hydroxide. This reaction produces ammonia gas, as shown in the ionic equation below:

NH4+(aq) + OH(aq) → NH3(g) + H2O(l)

The ammonia gas given off can then be tested as described above.