Sulfur Dioxide — properties & hazards overview
Boiling point
−10.0 °C
Melting point
−72.7 °C
Vapour density (air=1)
~ 2.3 (heavier than air)
Flammability
Non-flammable
Toxicity
strong irritant
Flammability
not flammable
Chronic risk
respiratory effects
Environmental
acid deposition
| Property | Value / Note |
|---|---|
| Chemical formula | SO₂ |
| Molar mass | 64.07 g/mol |
| Physical state (20 °C) | Colourless, suffocating gas (liquefies under pressure/low temperature) |
| Odour / threshold | Pungent, choking / ~ 0.3–1 ppm (odour not reliable at higher levels) |
| Solubility in water | Moderate–high; forms sulfurous acid (H₂SO₃/HSO₃⁻) |
| Reactivity | Acidic gas; oxidises to sulfate; corrosive in moist environments |
| Typical sources/uses | Combustion of sulfur fuels, smelters, pulp & paper, food/beverage sterilisation, chemicals |
*Values are indicative; verify with current SDS and standards for design and safety.