Ammonia is produced in the human body and is also commonly found in nature. It is essential in the body as a building block for making proteins and other complex molecules. In nature, ammonia occurs in soil from bacterial processes. It is also produced when plants, animals, and animal wastes decay.

Amphotericity of ammonia

One of the most characteristic properties of ammonia is its basicity. Ammonia is considered to be a weak base. It combines with acids to form ammonium salts; thus, with hydrochloric acid, it forms ammonium chloride (sal ammoniac); with nitric acid, ammonium nitrate, etc. Perfectly dry ammonia gas will not combine with perfectly dry hydrogen chloride gas; moisture is necessary to bring about the reaction.

As a demonstration experiment under air with ambient moisture, opened bottles of concentrated ammonia and hydrochloric acid solutions produce a cloud of ammonium chloride, which seems to appear 'out of nothing' as the salt aerosol forms where the two diffusing clouds of reagents meet between the two bottles.

NH3 + HCl → [NH4]Cl

The salts produced by the action of ammonia on acids are known as the ammonium salts and all contain the ammonium ion ([NH4]+).

Although ammonia is well known as a weak base, it can also act as an extremely weak acid. It is a protic substance and is capable of the formation of amides (which contain the NH?2ion). For example, lithium dissolves in liquid ammonia to give a blue solution (solvated electron) of lithium amide:

2 Li + 2 NH3 → 2 LiNH2 + H2

Conjugate base of ammonium

The conjugate base of NH3 is NH2- which is known as the azide anion.

Production of ammonium

About 80% of the ammonia produced in industry is used in agriculture as fertilizer. Ammonia is also used as a refrigerant gas, to purify water supplies, and in the manufacture of plastics, explosives, fabrics, pesticides, dyes, and other chemicals. It is found in many household and industrial-strength cleaning solutions. Cleaning solutions for industrial use contain higher concentrations of ammonia and can quickly cause irritation and burns.