Sulfur dioxide

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
3D model (JSmol)
3535237
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.028.359 Edit this at Wikidata
EC Number
  • 231-195-2
E number E220 (preservatives)
1443
KEGG
MeSH Sulfur+dioxide
RTECS number
  • WS4550000
UNII
UN number 1079, 2037
  • InChI=1S/O2S/c1-3-2 checkY
    Key: RAHZWNYVWXNFOC-UHFFFAOYSA-N checkY
  • InChI=1/O2S/c1-3-2
    Key: RAHZWNYVWXNFOC-UHFFFAOYAT
  • O=S=O
Properties
SO
2
Molar mass 64.066 g/mol
Appearance Colorless and pungent gas
Odor Pungent; similar to a just-struck match[1]
Density 2.619 kg m−3[2]
Melting point −72 °C; −98 °F; 201 K
Boiling point −10 °C (14 °F; 263 K)
94 g/L[3]
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[4]
Acidity (pKa) ~1.81
Basicity (pKb) ~12.19
−18.2·10−6 cm3/mol
Viscosity 12.82 μPa·s[5]
Structure
C2v
Digonal
Dihedral
1.62 D
Thermochemistry
248.223 J K−1 mol−1
−296.81 kJ mol−1
Hazards
GHS labelling:
GHS05: Corrosive GHS06: Toxic
Danger
H314, H331[6]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Lethal dose or concentration (LD, LC):
3000 ppm (mouse, 30 min)
2520 ppm (rat, 1 hr)[8]
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)[8]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 5 ppm (13 mg/m3)[7]
REL (Recommended)
TWA 2 ppm (5 mg/m3) ST 5 ppm (13 mg/m3)[7]
IDLH (Immediate danger)
100 ppm[7]
Related compounds
Related sulfur oxides
Sulfur monoxide
Sulfur trioxide
Disulfur monoxide
Related compounds
Ozone

Selenium dioxide

Tellurium dioxide
Polonium dioxide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

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 copper extraction and the burning of sulfur-bearing fossil fuels.[9]

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".[10]

  1. ^ Sulfur dioxide Archived December 30, 2019, at the Wayback Machine, U.S. National Library of Medicine
  2. ^ "Sulfur Dioxide". Archived from the original on September 24, 2023. Retrieved March 22, 2024., U.S. National Library of Medicine
  3. ^ Lide DR, ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
  4. ^ "Hazardous Substances Data Bank".
  5. ^ Miller J Jr, Shah P, Yaws C (1976). "Correlation constants for chemical compounds". Chemical Engineering. 83 (25): 153–180. ISSN 0009-2460.
  6. ^ "C&L Inventory".
  7. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0575". National Institute for Occupational Safety and Health (NIOSH).
  8. ^ a b "Sulfur dioxide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  9. ^ Cite error: The named reference Greenwood was invoked but never defined (see the help page).
  10. ^ Wothers P (2019). Antimony, Gold, and Jupiter's Wolf: How the Elements Were Named. Oxford University Press. ISBN 978-0-19-965272-3.

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