Nomenclature
CAS number: 7783-06-4
Sulfureted hydrogen; “hydrosulfuric acid”.
H
2S; mol wt 34.08.
H 5.92%, S 94.09%.
Description and 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).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.