Ammonium thiosulfate

Ammonium thiosulfate
Names
	IUPAC name Diammonium thiosulfate
	Other names Ammonium thiosulphate, ATS
Identifiers
CAS Number	7783-18-8 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:147402;
ChemSpider	4807475 ;
ECHA InfoCard	100.029.074
PubChem CID	6096946;
UNII	BKH1729645 ;
CompTox Dashboard (EPA)	DTXSID6029703 ;
	InChI InChI=1S/2H3N.H2O3S2/c;;1-5(2,3)4/h21H3;(H2,1,2,3,4) Key: XYXNTHIYBIDHGM-UHFFFAOYSA-N ; InChI=1S/2H3N.H2O3S2/c;;1-5(2,3)4/h21H3;(H2,1,2,3,4);
	SMILES [O-]S([O-])(=O)=S.[NH4+].[NH4+];
Properties
Chemical formula	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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	Infobox references

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]

References

MSDS - Ammonium Thiosulfate
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.
Praní černobílých filmů a papírů
Keller, Karlheinz (2005). "Photography". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_001.
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.
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.

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[1] MSDS - Ammonium Thiosulfate

[Ullmann-2] 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.

[3] Praní černobílých filmů a papírů

[Ullmann2-4] Keller, Karlheinz (2005). "Photography". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_001.

[5] 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.

[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.

[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. doi:10.3155/1047-3289.61.5.511. PMID 21608491. S2CID 44546628.