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Hydrogen sulfide

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 Sulfhydric acid
Identifiers
CAS Number	7783-06-4 Y
3D model (Jmol)	Interactive image
3DMet	B01206
Beilstein Reference	3535004
ChEBI	CHEBI:16136 Y
ChemSpider	391 Y
ECHA InfoCard	100.029.070
EC Number	231-977-3
Gmelin Reference	303
KEGG	C00283 Y
MeSH	Hydrogen+sulfide
PubChem CID	402
RTECS number	MX1225000
UNII	YY9FVM7NSN Y
UN number	1053
InChI InChI=1S/H2S/h1H2 Y Key: RWSOTUBLDIXVET-UHFFFAOYSA-N Y InChI=1/H2S/h1H2 Key: RWSOTUBLDIXVET-UHFFFAOYAJ
SMILES S
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 (pKa)	7.0
Basicity (pKb)	12.9
Magnetic susceptibility (χ)	−25.5·10−6 cm3/mol
Refractive index (nD)	1.000644 (0 °C)
Structure
Point group	C2v
Molecular shape	Bent
Dipole moment	0.97 D
Thermochemistry
Specific heat capacity (C)	1.003 J K−1 g−1
Std molar entropy (So298)	206 J mol−1 K−1
Std enthalpy of formation (ΔfHo298)	−21 kJ mol−1
Hazards
Safety data sheet	External MSDS
EU classification (DSD)	F+ T+ N
R-phrases	R12, R26, R50
S-phrases	(S1/2), S9, S16, S36, S38, S45, S61
NFPA 704	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)
LCLo (lowest published)	600 ppm (human, 30 min) 800 ppm (human, 5 min)
US health exposure limits (NIOSH):
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
Related compounds	Phosphine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Hydrogen sulfide is the chemical compound with the formula H
2S. It is a colorless gas with the characteristic foul odor of rotten eggs. It is very poisonous, corrosive, and flammable.

Hydrogen sulfide often results from the microbial breakdown of organic matter in the absence of oxygen gas, such as in swamps and sewers; this process is commonly known as anaerobic digestion. H
2S also occurs in volcanic gases, natural gas, and in some sources of well water. The human body produces small amounts of H
2S and uses it as a signaling molecule.

Swedish chemist Carl Wilhelm Scheele is credited with having discovered hydrogen sulfide in 1777.

The British English spelling of this compound is hydrogen sulphide, but this spelling is not recommended by the International Union of Pure and Applied Chemistry or the Royal Society of Chemistry.

Hydrogen sulfide is slightly heavier than air; a mixture of H
2S and air can be explosive. Hydrogen sulfide and oxygen burn with a blue flame to form sulfur dioxide (SO
2) and water. In general, hydrogen sulfide acts as a reducing agent, especially in the presence of base, which forms SH⁻.