A salt is a compound formed when the hydrogen ion of an acid is partially or totally replaced by a metal or ammonium ion. There are 2 types of salt:

Acidic salts: these salts are formed when the hydrogen ions of an acid is only partially replaced by a metal ion or the ammonium ion. Examples of acid salts are sodium bicarbonate (NaHCO₃), sodium hydrosulfide (NaHS), sodium bisulfate (NaHSO₄), monosodium phosphate (NaH₂PO₄) and disodium phosphate(Na₂HPO₄).

Example: Sodium bisulfate (NaHSO₄)

Sodium bisulphate is formed by the partial neutralization of sulphuric acid by sodium hydroxide.

NaOH_(aq) + H₂SO4 _(aq) → NaHSO4 + H₂

Normal salts: these are salts formed when the hydrogen ions of an acid are completely replaced by a metal ion or ammonium ion.

Example:

2NaOH+ H₂SO4  →   Na₂SO4 + 2H₂0, where all hydrogen ions are replaced

Salts may be either soluble or insoluble.

Insoluble salts may be prepared in the following ways:

-direct combination

-precipitation

Soluble salts can be prepared by the following reactions:

-acid and an alkali

-an acid and excess  carbonate hydrogen carbonate

-an acid and an excess metal oxide

-an acid and an excess active metal