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Sulfur dioxide



Name Sulfur dioxide
Chemical formula SO2
Appearance Colourless gas


Formula weight 64.1 amu
Melting point 198 K (-75 °C)
Boiling point 263 K (-10 °C)
Density 1.4 ×103 kg/m3 (liquid)
Solubility 9.4 g in 100g water


ΔfH0gas -296.84 kJ/mol
ΔfH0liquid ? kJ/mol
ΔfH0solid ? kJ/mol
S0gas, 1 bar 248.21 J/mol·K
S0liquid, 1 bar ? J/mol·K
S0solid ? J/mol·K


Ingestion Relatively low toxicity, may cause nausea and vomiting. Long term hazards known.
Inhalation Extreme irritation.
Skin Hazardous when cryogenic or compressed.
Eyes Hazardous when cryogenic or compressed.
More info Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.

Disclaimer and references

Sulfur dioxide (spelt in British English Sulphur dioxide) has the chemical formula SO2. The gas is irritant to the lungs.

It is produced by volcanoes and in various industrial processes. In particular, poor-quality coal and petroleum contains sulfur compounds, and generates sulfur dioxide when burned: the gas reacts with water and atmospheric oxygen to form sulfuric acid (H2SO4) - and thus Acid rain.

Sulfur dioxide is frequently used as a food additive: particularly as a preservative in alcoholic drinks.