Sulphur dioxide is a colourless gas, about 2.5 times as heavy as air, with a suffocating smell, faint sweetish odour.
S + O2 ==> SO2
Sulphur dioxide is usually made in the laboratory by heating concentrated sulphuric acid with copper turnings.
Cu + 2 H2SO4 ==> CuSO4 + SO2 + 2 H2O
Sulphur dioxide is also reduced when heated with mercury, silver or charcoal, C. Reduction with Sulphur, S, is very slow.
Sulphur dioxide is released by the action of acids on sulphites or acid sulphites (e.g. by dropping concentrated sulphuric acid into a concentrated solution of sodium hydrogen sulphite).
NaHSO3 + H2SO4 ==> NaHSO4 + SO2 + H2O
Sulphur Dioxide is an acidic oxide which reacts with water to give sulphurous acid.
SO2 + H2O ==> H2SO3
Sulphur dioxide is a good reducing and oxidising agent.
The structural formula of sulphur dioxide is SO2, and it is a covalent, planer molecule which is v-shaped with an angle of 120 degrees.
Large quantities of sulphur dioxide are used in the contact process for the manufacture of sulphuric acid.
Sulphur dioxide is used in bleaching wool or straw, and as a disinfectant.
Liquid sulphur dioxide has been used in purifying petroleum products.