There are various salts of importance in formulations, especially in detergent formulations, and a basic knowledge of their properties and behaviour is essential to understanding the chemistry behind many preparations. Quite often salts, alkalis and chelating agents (sequestrants) are referred to in the detergent industry as builders.

In general we can regard a salt as comprising an acid part (anion) and a part derived from a base (cation). Usually the cation is a metal ion but sometimes it is ammonium and its derivatives. As seen above there are different strengths of acids and bases as shown by the dissociation constants and the neutralization reactions that they can take part in lead to many different salts each one of which has properties relating to the strength of the acid and base from which it was derived.

Common salt, sodium chloride, is a salt derived from a strong acid, hydrochloric acid, and a strong base, sodium hydroxide.

Salts formed by neutralization of strong acids and strong bases are neutral salts and in solution give solutions of around pH 7. On the other hand if either the acid or the base is strong and the other is weak the salt produced is far from neutral.

Sodium carbonate, for instance, is derived from a weak acid, carbonic acid, and a strong base, sodium hydroxide. When dissolved it gives a solution of high pH, i.e., it is alkaline.

This reaction is seen where sodium hydroxide is left open to the air and turns...