Sulfur dioxide

chemical compound
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Sulfur dioxide (also sulphur dioxide) is the chemical compound with the formula SO2. It is a gas. It smells like burnt matches or rotten eggs. It can also cause suffocation. Sulfur dioxide is produced by volcanoes and in various industrial processes. It is also used to protect wine from oxygen and bacteria. It can be produced by burning sulfur. It dissolves in water to produce sulfurous acid. It can be oxidized to trioxide, which is dissolved in sulfuric acid to make more sulfuric acid. It is used to make sulfites.

Sulfur dioxide
Skeletal formula sulfur dioxide with assorted dimensions
Spacefill model of sulfur dioxide
The Lewis structure of sulfur dioxide (SO2), showing unshared electron pairs.
Names
IUPAC name
Sulfur dioxide
Other names
Sulfurous anhydride
Sulfur(IV) oxide
Identifiers
  • 7446-09-5 checkY
3D model (JSmol)
Beilstein Reference 3535237
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.028.359
EC Number
  • 231-195-2
E number E220 (preservatives)
Gmelin Reference 1443
KEGG
MeSH Sulfur+dioxide
RTECS number
  • WS4550000
UNII
UN number 1079, 2037
  • O=S=O
Properties
SO
2
Molar mass 64.066 g mol−1
Appearance Colorless gas
Odor Pungent; similar to a just-struck match[1]
Density 2.6288 kg m−3
Melting point −72 °C; −98 °F; 201 K
Boiling point −10 °C (14 °F; 263 K)
94 g/L[2]
forms sulfurous acid
Vapor pressure 237.2 kPa
Acidity (pKa) 1.81
Basicity (pKb) 12.19
−18.2·10−6 cm3/mol
Viscosity 0.403 cP (at 0 °C)
Structure
C2v
Digonal
Dihedral
1.62 D
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−296.81 kJ mol−1
Standard molar
entropy
So298
248.223 J K−1 mol−1
Hazards
NFPA 704

0
3
0
 
U.S. Permissible
exposure limit (PEL)
TWA 5 ppm (13 mg/m3)
Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sources

change
  1. Sulfur dioxide Archived 2019-12-30 at the Wayback Machine, U.S. National Library of Medicine
  2. Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.