Ammonium thiosulfate
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Names | |||
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IUPAC name
Diammonium thiosulfate
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Other names
Ammonium thiosulphate, ATS
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Identifiers | |||
3D model (JSmol)
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ChEBI | |||
ChemSpider | |||
ECHA InfoCard | 100.029.074 | ||
PubChem CID
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UNII | |||
CompTox Dashboard (EPA)
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Properties | |||
H8N2O3S2 | |||
Molar mass | 148.20 g·mol−1 | ||
Appearance | colorless or white solid | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ammonium thiosulfate (ammonium thiosulphate in British English) is an inorganic compound with the formula (NH4)2S2O3. It is white crystalline solid with ammonia odor, readily soluble in water, slightly soluble in acetone and insoluble in ethanol and diethyl ether.[1]
Production
It is produced by treating ammonium sulfite with sulfur:[2]
- (NH4)2SO3 + S → (NH4)2S2O3
Applications
Ammonium thiosulfate is used in photographic fixer. It is a so-called rapid fixer, acting more quickly than sodium thiosulfate fixers.[3] Fixation involves these chemical reactions (illustrated for silver bromide):[4]
- AgBr + 2 (NH4)2S2O3 → (NH4)3[Ag(S2O3)2] + NH4Br
- AgBr + 3 (NH4)2S2O3 → (NH4)5[Ag(S2O3)3] + NH4Br
Ammonium thiosulfate is also used for leaching of gold and silver. It works with presence of copper as a catalyst here. This process is a nontoxic alternative gold cyanidation.[5] The advantage to ammonium thiosulfate is that the pyrolysis of its silver complexes leaves a residue solely of silver sulfide, in contrast to complexes derived from sodium thiosulfate.[2]
Other
Ammonium thiosulfate can be used as a fertilizer.[6] As suggested by some research studies, it can be used as an additive to coal-waste mixtures to reduce formation of very dangerous dioxins and furans.[7]
Safety
LD50 (oral, rat) is 2890 mg/kg.[2]
See also
References
- ^ MSDS - Ammonium Thiosulfate
- ^ a b c J. J. Barbera; A. Metzger; M. Wolf (2012). "Sulfites, Thiosulfates, and Dithionites". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_477. ISBN 978-3527306732.
- ^ Praní černobílých filmů a papírů
- ^ Keller, Karlheinz (2005). "Photography". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_001. ISBN 978-3527306732.
- ^ Aylmore, M.G; Muir, D.M (2001). "Thiosulfate leaching of gold—A review". Minerals Engineering. 14 (2): 135–174. doi:10.1016/S0892-6875(00)00172-2.
- ^ McCarty, G. W.; Bremner1, J. M.; Krogmeier1, M. J. (1990). "Evaluation of ammonium thiosulfate as a soil urease inhibitor". Fertilizer Research. 24 (3): 135–139. doi:10.1007/BF01073581. S2CID 28574791.
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: CS1 maint: numeric names: authors list (link) - ^ Wielgosiński, Grzegorz (2011). "The Reduction of Dioxin Emissions from the Processes of Heat and Power Generation". Journal of the Air & Waste Management Association. 61 (5): 511–526. doi:10.3155/1047-3289.61.5.511. PMID 21608491. S2CID 44546628.