Sulfur Dioxide (SO2) is a colorless gas of a distinctive, strong odor. It is obtained from either pyrite or sulfur by burning. It is toxic and a strong irritant and is classified as one of the major air pollutants. It is widely used in the production of sulfur-containing chemicals, in the paper industry and in metal refining. It is also used as a solvent, as a food additive and as a reaction medium.
| Molecular weight: 64.06 | Critical temperature:430.8 K |
| Melting point: 198.7 K | Critical pressure:7.884 MPa |
| Boiling point:263.0 K | Critical density:525 kg/m3 |
| Normal vapor density:2.86 kg/m3 | (@0°C, 101.3 kPa) |