Ammonium thiosulfate

Ammonium thiosulfate
Names
IUPAC name
Diammonium thiosulfate
Other names
Ammonium thiosulphate, ATS
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.029.074 Edit this at Wikidata
UNII
  • InChI=1S/2H3N.H2O3S2/c;;1-5(2,3)4/h2*1H3;(H2,1,2,3,4) checkY
    Key: XYXNTHIYBIDHGM-UHFFFAOYSA-N checkY
  • InChI=1S/2H3N.H2O3S2/c;;1-5(2,3)4/h2*1H3;(H2,1,2,3,4)
  • [O-]S([O-])(=O)=S.[NH4+].[NH4+]
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):
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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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.

Production

It is produced by treating ammonium sulfite with sulfur at temperatures between 85 and 110 °C:

[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. Fixation involves these chemical reactions (illustrated for silver bromide):

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. 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.

Other

Ammonium thiosulfate can be used as a fertilizer. 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.

Safety

The LD50 (oral, rat) is 2890 mg/kg.

See also

References

  1. ↑ MSDS - Ammonium Thiosulfate
  2. 1 2 3 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.
  3. ↑ "Praní černobílých filmů a papírů". Archived from the original on 2012-03-27. Retrieved 2011-07-30.
  4. ↑ Keller, Karlheinz (2005). "Photography". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_001. ISBN 978-3-527-30673-2.
  5. ↑ 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.
  6. ↑ 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.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  7. ↑ 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.