Hydrogen Sulfide

Title: Hydrogen Sulfide
CAS Registry Number: 7783-06-4
Additional Names: Sulfureted hydrogen; "hydrosulfuric acid"
Molecular Formula: H2S
Molecular Weight: 34.08
Percent Composition: H 5.92%, S 94.09%
Literature References: Evolved from numerous environmental natural sources such as bacterial decomposition of vegetable and animal proteinaceous material. Occurs naturally as a component of crude petroleum, natural gas, volcanic gas and sulfur springs. Also a pollutant released into the environment as a by-product of a variety of industrial operations. Lab prepn: Bickford, Wilkinson, Inorg. Synth. 1, 111 (1939). Purification: Ward et al., ibid. 3, 14 (1950). Toxicity studies: E. H. Vernot et al., Toxicol. Appl. Pharmacol. 42, 417 (1977); M. F. Tansy et al., J. Toxicol. Environ. Health 8, 71-88 (1981). Review of toxicity and properties: R. O. Beauchamp, Jr., et al., Crit. Rev. Toxicol. 13, 25-97 (1984); of toxicology: R. J. Reiffenstein et al., Annu. Rev. Pharmacol. Toxicol. 32, 109-134 (1992); and human exposure: Toxicological Profile for Hydrogen Sulfide (PB99-166696, 1999) 217 pp.
Properties: Gas with characteristic odor of rotten eggs, perceptible in air at concns of 0.02-0.13 ppm, sweetish taste. Flammable, poisonous. Burns in air with pale blue flame. Ignition temp 260°. Explosive limits when mixed with air: lower limit 4.3% by vol, upper limit 46% by vol. mp -85.49°; bp -60.33°: Giauque, Blue, J. Am. Chem. Soc. 58, 831 (1936). Heavier than air; 1.5392 g/l (0°; 760 mm). dgas 1.19 (air = 1.00). Vapor pressure 18.75 ´ 105 Pa. One gram H2S dissolves in 187 ml water at 10°, in 242 ml water at 20°, in 314 ml water at 30°; in 94.3 ml abs alcohol at 20°; in 48.5 ml ether at 20°. Sol in glycerol, gasoline, kerosene, carbon disulfide, crude oil. Water solns of H2S are not stable, absorbed oxygen causes the formation of elemental sulfur, and the solns become turbid rapidly. In a 50:50 v/v mixture of glycerol and water the precipitation of sulfur is retarded considerably. pH of freshly prepd satd water soln 4.5. pKa1 7.04; pKa2 11.96. LC50 in mice, rats (ppm): 634, 712 (1 hr inhalation) (Vernot). LC50 in rats (ppm): 444 (4 hr inhalation) (Tansy).
Melting point: mp -85.49°
Boiling point: bp -60.33°: Giauque, Blue, J. Am. Chem. Soc. 58, 831 (1936)
pKa: pKa1 7.04; pKa2 11.96
Density: dgas 1.19 (air = 1.00)
Toxicity data: LC50 in mice, rats (ppm): 634, 712 (1 hr inhalation) (Vernot); LC50 in rats (ppm): 444 (4 hr inhalation) (Tansy)
CAUTION: Highly toxic irritant and chemical asphyxiant; overexposure can be fatal. Insidious poison, since sense of smell may be fatigued and fail to give warning of high concns. Direct contact with gas may cause irritation of eyes and respiratory tract resulting in keratoconjunctivitis, photophobia, lacrimation, corneal opacity; rhinitis, laryngitis, cough, bronchopneumonia. Direct contact with solution may cause skin irritation, erythema. Potential symptoms of overexposure by inhalation include salivation, GI disturbances; giddiness, headache, vertigo, confusion, unconsciousness; tachypnea, tachycardia, sweating, fatigue. Exposure to very high vapor concentrations may result in systemic intoxication leading to paralysis of respiratory center of brain, apnea and sudden collapse. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section III, pp 198-202; NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 170.
Use: To produce elemental sulfur and sulfuric acid; in manuf of heavy water and other chemicals; in metallurgy; as analytical reagent.
Hydrogen Telluride Hydrogen Tetracarbonylferrate(II) Hydrohydrastinine Hydromorphone Hydrone?

Hydrogen sulfide
Skeletal formula of hydrogen sulfide with two dimensions
Hydrogen-sulfide-3D-balls.png Spacefill model of hydrogen sulfide
Identifiers
CAS number 7783-06-4 YesY
PubChem 402
ChemSpider 391 YesY
UNII YY9FVM7NSN YesY
EC number 231-977-3
UN number 1053
KEGG C00283 YesY
MeSH Hydrogen+sulfide
ChEBI CHEBI:16136 YesY
ChEMBL CHEMBL1200739 N
RTECS number MX1225000
Beilstein Reference 3535004
Gmelin Reference 303
3DMet B01206
Jmol-3D images Image 1
Properties
Molecular formula H2S
Molar mass 34.08 g mol−1
Appearance Colorless gas
Odor faint rotten egg
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[2][3]
Basicity (pKb) 6.95
Refractive index (nD) 1.000644 (0 °C)[4]
Structure
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[5]
Std enthalpy of
formation ΔfHo298
−21 kJ·mol−1[5]
Hazards
EU Index 016-001-00-4
EU classification Flammable F+ Very Toxic T+ Dangerous for the Environment (Nature) N
R-phrases R12, R26, R50
S-phrases (S1/2), S9, S16, S36, S38, S45, S61
NFPA 704
NFPA 704.svg
4
4
0
Flash point -82.4 °C[6]
Autoignition temperature 232 °C; 450 °F; 505 K
Explosive limits 4.3–46%
Related compounds
Related hydrogen chalcogenides Water
Hydrogen selenide
Hydrogen telluride
Hydrogen polonide
Hydrogen disulfide
Sulfanyl
Related compounds Phosphine
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Hydrogen sulfide (British English: hydrogen sulphide, but this spelling is not recommended by the International Union of Pure and Applied Chemistry nor the Royal Society of Chemistry) is the chemical compound with the formula H
2
S
. It is a colorless gas with the characteristic foul odor of rotten eggs; it is heavier than air, very poisonous, corrosive, flammable and explosive.

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

Dissolved in water, hydrogen sulfide is known as hydrosulfuric acid or sulfhydric acid, a weak acid.

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