Chemistry:Disulfurous acid

Disulfurous acid

Names
IUPAC name disulfurous acid
Other names pyrosulfurous acid
Identifiers
CAS Number	33669-61-3 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29252 Y
ChemSpider	26062 Y
PubChem CID	28020
UNII	CG8XAU5U77 Y
InChI InChI=1S/H2O5S2/c1-6(2)7(3,4)5/h(H,1,2)(H,3,4,5) Y Key: WBZKQQHYRPRKNJ-UHFFFAOYSA-N Y InChI=1S/H2O5S2/c1-6(2)7(3,4)5/h(H,1,2)(H,3,4,5)
SMILES O=S(=O)(O)S(=O)O
Properties
Chemical formula	H 2S 2O 5
Molar mass	146.13 g·mol−1
Conjugate base	Disulfite
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

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Disulfurous acid, metabisulfurous acid or pyrosulfurous acid is an oxoacid of sulfur with the formula H
2S
2O
5. Its structure is HO–S(=O)
2–S(=O)–OH. The salts of disulfurous acid are called disulfites or metabisulfites. Disulfurous acid is, like sulfurous acid (H
2SO
3), a phantom acid, which does not exist in the free state. In contrast to disulfate (S
2O2−
7), disulfite has two directly connected sulfur atoms. The oxidation state of the sulfur atom bonded to three oxygen atoms is +5 and its valence is 6, while that of the other sulfur is +3 and 4 respectively.

Disulfurous acid ¹H NMR spectrum.