Hydrogen sulfide | |
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Other names |
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Identifiers | |
CAS number | |
PubChem | |
EC number | 231-977-3 |
KEGG | C00283 |
MeSH | |
ChEBI | CHEBI:16136 |
RTECS number | MX1225000 |
SMILES | [H]S[H] |
Beilstein Reference | 3535004 |
Gmelin Reference | 303 |
3DMet | B01206 |
Properties | |
Molecular 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, 191 K, -116 °F |
Boiling point | |
Solubility in water | 4 g dm−3 (at 20 °C) |
Vapor pressure | 1740 kPa (at 21 °C) |
Acidity (pKa) | 7.0 |
−25.5·10−6 cm3/mol | |
Refractive index (nD) | 1.000644 (0 °C) |
Structure | |
C2v | |
Molecular shape | Bent |
Dipole moment | 0.97 D |
Thermochemistry | |
Std enthalpy of formation ΔfH | −21 kJ mol−1 |
Standard molar entropy S | 206 J mol−1 K−1 |
Specific heat capacity, C | 1.003 J K−1 g−1 |
Hazards | |
EU classification | F+ T+ N |
Main hazards | Flammable and highly toxic |
NFPA 704 | |
R-phrases | R12, R26, R50 |
S-phrases | (S1/2), S9, S16, S36, S38, S45, S61 |
Explosive limits | 4.3–46% |
U.S. Permissible exposure limit (PEL) | C 20 ppm; 50 ppm [10-minute maximum peak] |
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
Hydrogen sulfide (British English: hydrogen sulphide) is the chemical compound with the formula H2S, 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.