SO₂
Compound · Oxide
Sulfur dioxide
二氧化硫
Sulfur dioxide (二氧化硫), formula SO₂, is a oxide with a molar mass of 64.07 g/mol (CAS 7446-09-5). Colourless gas with a pungent smell; readily dissolves in water as sulfurous acid.
Key facts
| Molar mass | 64.07 g/mol |
|---|---|
| Category | Oxide |
| State at 25°C | Gas |
| CAS | 7446-09-5 |
Structure
O=S=O
Bent, polar molecule
Physical properties
| Appearance | Colourless gas with a pungent smell |
|---|---|
| Melting point | −72 °C |
| Boiling point | −10 °C |
| Density | 2.62 g/L (气体) |
| Solubility | Readily dissolves in water as sulfurous acid |
Key reactions
SO₂ + H₂O ⇌ H₂SO₃
Dissolves in water as sulfurous acid
2SO₂ + O₂ →(催化) 2SO₃
Key step of the contact process for sulfuric acid
Main uses
- Intermediate in sulfuric-acid manufacture
- Bleaching pulp and food preservation (regulated)
- Antioxidant in wine and dried fruit
Hazard
ModerateToxic irritant gas; a major contributor to acid rain
Constituent elements
Data sources
Molar mass is computed from IUPAC (CIAAW) standard atomic weights; formula, properties and reactions can be verified on PubChem, NIST and Wikipedia. The CAS number is the substance's unique registry identifier. Educational reference only.