Sulfur dioxide
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| Names | |||
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| IUPAC name
Sulfur dioxide | |||
Other names
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| Identifiers | |||
3D model (JSmol) |
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| 3535237 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.028.359 | ||
| EC Number |
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| E number | E220 (preservatives) | ||
| 1443 | |||
| KEGG | |||
| MeSH | Sulfur+dioxide | ||
PubChem CID |
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| RTECS number |
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| UNII | |||
| UN number | 1079, 2037 | ||
CompTox Dashboard (EPA) |
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| Properties | |||
| SO 2 | |||
| Molar mass | 64.066 g/mol | ||
| Appearance | Colorless gas | ||
| Odor | Pungent; similar to a just-struck match | ||
| Density | 2.619 kg m−3 | ||
| Melting point | −72 °C; −98 °F; 201 K | ||
| Boiling point | −10 °C (14 °F; 263 K) | ||
| 94 g/L forms sulfurous acid | |||
| Vapor pressure | 230 kPa at 10 °C; 330 kPa at 20 °C; 462 kPa at 30 °C; 630 kPa at 40 °C | ||
| Acidity (pKa) | ~1.81 | ||
| Basicity (pKb) | ~12.19 | ||
| −18.2·10−6 cm3/mol | |||
| Viscosity | 12.82 μPa·s | ||
| Structure | |||
| C2v | |||
| Digonal | |||
| Dihedral | |||
| 1.62 D | |||
| Thermochemistry | |||
Std molar entropy (S⦵298) |
248.223 J K−1 mol−1 | ||
Std enthalpy of formation (ΔfH⦵298) |
−296.81 kJ mol−1 | ||
| Hazards | |||
| GHS labelling: | |||
| Danger | |||
| H314, H331, H370 | |||
| NFPA 704 (fire diamond) | |||
| Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration) |
3000 ppm (mouse, 30 min) 2520 ppm (rat, 1 hr) | ||
LCLo (lowest published) |
993 ppm (rat, 20 min) 611 ppm (rat, 5 hr) 764 ppm (mouse, 20 min) 1000 ppm (human, 10 min) 3000 ppm (human, 5 min) | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) |
TWA 5 ppm (13 mg/m3) | ||
REL (Recommended) |
TWA 2 ppm (5 mg/m3) ST 5 ppm (13 mg/m3) | ||
IDLH (Immediate danger) |
100 ppm | ||
| Related compounds | |||
| Sulfur monoxide Sulfur trioxide Disulfur monoxide | |||
Related compounds |
Ozone | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |||
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula SO
2. It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of metals refining and the burning of sulfur-bearing fossil fuels.
Sulfur dioxide is somewhat toxic to humans, although only when inhaled in relatively large quantities for a period of several minutes or more. It was known to medieval alchemists as "volatile spirit of sulfur".