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]
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 | |
[NH4]2S2O3 | |
Molar mass | 148.20 g·mol−1 |
Appearance | colorless or white, hygroscopic solid |
Density | 1.679 g/cm3 |
Melting point | decomposes at 100 °C |
173 g/100 mL (20 °C) | |
Solubility | slightly soluble in acetone insoluble in alcohol |
Structure | |
monoclinic | |
Hazards | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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2980 mg/kg (rat, oral) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production
editIt is produced by treating ammonium sulfite with sulfur at temperatures between 85 and 110 °C:[2]
- [NH4]2SO3 + S → [NH4]2S2O3
Applications
editAmmonium 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] + [NH4]Br
- AgBr + 3 [NH4]2S2O3 → [NH4]5[Ag(S2O3)3] + [NH4]Br
Also exploiting the stability of thiosulfate coordination complexes, ammonium thiosulfate is also used for leaching of gold and silver. It works with presence of copper as a catalyst. 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
editAmmonium thiosulfate can be used as a fertilizer.[6] As suggested by some research studies, it can also be used as an additive to coal-waste mixtures to reduce formation of dioxins and furans during combustion.[7]
Safety
editSee also
editReferences
edit- ^ MSDS - Ammonium Thiosulfate
- ^ Jump up to: 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". Archived from the original on 2012-03-27. Retrieved 2011-07-30.
- ^ 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. Bibcode:2001MiEng..14..135A. 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. Bibcode:2011JAWMA..61..511W. doi:10.3155/1047-3289.61.5.511. PMID 21608491. S2CID 44546628.