Sulphur dioxide - SO2

Sulphur dioxide is a colourless, poisonous gas with pungent smell and sour taste. Large amounts of sulphur dioxide are formed in nature by volcanic activity and oxidation of organic sulphides.

The most common use of sulphur dioxide is in the production of sulphuric acid (H2SO4), but sulphur dioxide is also used as a bleaching agent in the pulp and paper industry.

The major hazard of sulphur dioxide is inhalation. 

Properties

Molecular weight 64.064 g/mol.

Gaseous phase Gas density (1.013 bar at boiling point): 3.0571 kg/m3
Gas density (1.013 bar and 15 °C (59 °F)): 2.7633 kg/m3

Liquid phase Boiling point: -10.02 °C
 Liquid density (1.013 bar at boiling point): 1461.1 kg/m3

Critical point Critical temperature: 157.49 °C
 Critical pressure: 78.84 bar
 Critical density: 525 kg/m3