Sulphurous Acid Sulphurous acid is the strong acid produced by dissolving sulphur dioxide in water. Properties of Sulphurous Acid Sulphurous Acid, H2SO3, is a weak dibasic acid, known in the form of its salts.
Sulphurous acid is unstable and has never been isolated as a pure compound.
Preparation of Sulphurous acid Sulphurous acid is formed when sulphur dioxide is dissolved in water. H2SO3 Sulphurous acid is unstable and has never been isolated as a pure compound. It may be better represented by the following reactions. This is known as the ionisation of Sulphurous acid. The solution when heated in a sealed tube at 150 deg.