# Hydrogen sulfide

Hydrogen sulfide|  |
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| Ball-and-stick model of hydrogen sulfide | Spacefill model of hydrogen sulfide |

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| Names |
| Systematic IUPAC name
Hydrogen sulfide |
| Other names
* Dihydrogen monosulfide
* Dihydrogen sulfide
* Sewer gas
* Sulfane
* Sulfurated hydrogen
* Sulfureted hydrogen
* Sulfuretted hydrogen
* Sulfur hydride
* Hydrosulfuric acid
* Hydrothionic acid
* Thiohydroxic acid
* Sulfhydric acid
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| Identifiers |
| CAS Number | * 7783-06-4Y
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| 3D model (JSmol) | * Interactive image
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| 3DMet | * B01206
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| Beilstein Reference | 3535004 |
| ChEBI | * CHEBI:16136Y
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| ChEMBL | * ChEMBL1200739N
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| ChemSpider | * 391Y
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| ECHA InfoCard | 100.029.070 |
| EC Number | * 231-977-3
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| Gmelin Reference | 303 |
| KEGG | * C00283Y
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| MeSH | Hydrogen+sulfide |
| PubChem CID | * 402
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| RTECS number | * MX1225000
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| UNII | * YY9FVM7NSNY
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| UN number | 1053 |
| CompTox Dashboard (EPA) | * DTXSID4024149
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SMILES
* [H]S[H]
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| Properties |
| Chemical formula | H2S |
| Molar mass | 34.08 g·mol−1   |
| Appearance | Colorless gas |
| Odor | Rotten eggs |
| Density | 1.363 g dm−3 |
| Melting point | −82 °C (−116 °F; 191 K)  |
| Boiling point | −60 °C (−76 °F; 213 K)  |
| Solubility in water | 4 g dm−3 (at 20 °C) |
| Vapor pressure | 1740 kPa (at 21 °C) |
| Acidity (p*K*a) | 7.0 |
| Conjugate acid | Sulfonium |
| Conjugate base | Bisulfide |
| Magnetic susceptibility (χ) | −25.5·10−6 cm3/mol |
| Refractive index (*n*D) | 1.000644 (0 °C) |
| Structure |
| Point group | C2v |
| Molecular shape | Bent |
| Dipole moment | 0.97 D |
| Thermochemistry |
| Std enthalpy of formation Δf*H*~~o~~298 | −21 kJ mol−1 |
| Standard molar entropy *S*~~o~~298 | 206 J mol−1 K−1 |
| Specific heat capacity, *C* | 1.003 J K−1 g−1 |
| Hazards |
| **Occupational safety and health** (OHS/OSH): |
| Main hazards | Flammable and highly toxic |
| **NFPA 704** (fire diamond) |
4
4
0 |
| Flash point | −82.4 °C (−116.3 °F; 190.8 K)  |
| Autoignition temperature | 232 °C (450 °F; 505 K)  |
| Explosive limits | 4.3–46% |
| **Lethal dose** or concentration (LD, LC): |
| LC50 (median concentration) | * 713 ppm (rat, 1 hr)
* 673 ppm (mouse, 1 hr)
* 634 ppm (mouse, 1 hr)
* 444 ppm (rat, 4 hr)
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| LCLo (lowest published) | * 600 ppm (human, 30 min)
* 800 ppm (human, 5 min)
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| **NIOSH** (US health exposure limits): |
| PEL (Permissible) | C 20 ppm; 50 ppm [10-minute maximum peak] |
| REL (Recommended) | C 10 ppm (15 mg/m3) [10-minute] |
| IDLH (Immediate danger) | 100 ppm |
| Related compounds |
| Related hydrogen chalcogenides | * Water
* Hydrogen selenide
* Hydrogen telluride
* Hydrogen polonide
* Hydrogen disulfide
* Sulfanyl
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| Related compounds | Phosphine |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
| N verify (what is YN ?) |
| Infobox references |
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**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.

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".

## Occurrence

Deposit of sulfur on a rock, caused by volcanic gases containing hydrogen sulfide
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.

## Safety

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.

## Toxicity

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.

* "Hydrogen Sulfide", Committee on Medical and Biological Effects of Environmental Pollutants, University Park Press, 1979, Baltimore. ISBN 0-8391-0127-9

## Other websites

* 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