Thiosulfuric acid

Thiosulfuric acid

Names
IUPAC name sulfurothioic O-acid
Other names thiosulfuric acid dihydroxidooxidosulfidosulfur
Identifiers
CAS Number	7772-98-7
3D model (JSmol)	Interactive image
CompTox Dashboard (EPA)	DTXSID00159981
SMILES OS(=O)(=S)O
Properties
Chemical formula	H2S2O3
Molar mass	114.14408
Solubility in water	decomposes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Thiosulfuric acid is a sulfur oxoacid. The acid cannot be made by acidifying thiosulfate salts as the acid readily decomposes in water. The decomposition products can include, depending on the exact reaction conditions, sulfur, sulfur dioxide, hydrogen sulfide, polysulfanes, sulfuric acid and polythionates. Anhydrous methods of producing the acid include:

(in diethyl ether at -78°C )

H₂S + SO₃ → H₂S₂O₃•nEt₂O

Na₂S₂O₃+2HCl → 2NaCl + H₂S₂O₃•2Et₂O

The anhydrous acid decomposes below 0°C:

H₂S₂O₃ → H₂S + SO₃

There is an isomeric form, a white crystalline adduct, H₂S.SO₃ which can be prepared at low temperature.

See also

• Sulfur oxoacids for other sulfur oxoacids

Footnotes

1. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.