Hydrogen sulfide (British English: hydrogen sulphide) is the chemical compound with the formula H
2S, is a colorless, toxic, flammable gas that is responsible for the foul smell of rotten eggs and flatulence. It often results when bacteria break down organic matter if there is no oxygen. This happens in swamps, and sewers (alongside the process of anaerobic digestion). It also happens in volcanic gases, natural gas and some well waters. This is the smell that people often think to be that of sulfur. But sulfur itself does not smell.
|Systematic IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||34.08 g·mol−1|
|Density||1.363 g dm−3|
|Melting point||−82 °C (−116 °F; 191 K)|
|Boiling point||−60 °C (−76 °F; 213 K)|
|4 g dm−3 (at 20 °C)|
|Vapor pressure||1740 kPa (at 21 °C)|
Refractive index (nD)
|1.000644 (0 °C)|
|Std enthalpy of
|−21 kJ mol−1|
|206 J mol−1 K−1|
|Specific heat capacity, C||1.003 J K−1 g−1|
|EU classification||F+ T+ N|
|Main hazards||Flammable and highly toxic|
|R-phrases||R12, R26, R50|
|S-phrases||(S1/2), S9, S16, S36, S38, S45, S61|
exposure limit (PEL)
|C 20 ppm; 50 ppm [10-minute maximum peak]|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Hydrogen sulfide is also known as sulfane, sulfur hydride, sour gas, sulfurated hydrogen, hydrosulfuric acid, sewer gas and stink damp. IUPAC accepts the names "hydrogen sulfide" and "sulfane". When people speak of more complicated compounds they always use the term "sulfane".
Small amounts of hydrogen sulfide can be found in crude petroleum. Sour natural gas can contain up to 28%. But, sour natural gas must be cleaned before it can enter a long distance pipeline. Pipelines limit hydrogen sulfide to 3 grains per thousand cubic feet of natural gas. Volcanoes and hot springs give off some H2S, where it probably is made by the hydrolysis of sulfide minerals, i.e. MS + H2O to give MO + H2S.
Normal average concentration in clean air is about 0.0001-0.0002 ppm.
Hydrogen sulfide is a highly toxic and flammable gas. Because it is heavier than air it tends to accumulate at the bottom of poorly ventilated spaces.
Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected. The toxicity of H2S is comparable with that of hydrogen cyanide.
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- Perrin, D.D. (1982). Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution (2nd ed.). Oxford: Pergamon Press.
- Bruckenstein, S.; Kolthoff, I.M., in Kolthoff, I.M.; Elving, P.J. Treatise on Analytical Chemistry, Vol. 1, pt. 1; Wiley, NY, 1959, pp. 432–433.
- Patnaik, Pradyot (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN 0-07-049439-8.
- Zumdahl, Steven S. (2009). Chemical Principles (6th ed.). Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
- "Southern Natural Gas Company Tariff, General Terms and Conditions Section 3.1(b)". Archived from the original on March 5, 2016. Retrieved October 18, 2011.
- International Chemical Safety Card 0165
- Concise International Chemical Assessment Document 53
- National Pollutant Inventory - Hydrogen sulfide fact sheet Archived 2006-03-09 at the Wayback Machine
- NIOSH Pocket Guide to Chemical Hazards
- MSDS safety data sheet Archived 2007-05-15 at the Wayback Machine
- Abstract of survey article on H2S as used by the body, by P. Kamoun
- Computational Chemistry Wiki Archived 2008-12-07 at the Wayback Machine