Dithionous acid

Dithionous acid
Names
	IUPAC name Dithionous acid
	Other names Hydrosulfurous acid; Hyposulfurous acid
Identifiers
CAS Number	15959-26-9 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:29253 ;
ChemSpider	22898 ;
PubChem CID	24490;
CompTox Dashboard (EPA)	DTXSID70274771 ;
	InChI InChI=1S/H2O4S2/c1-5(2)6(3)4/h(H,1,2)(H,3,4) Key: GRWZHXKQBITJKP-UHFFFAOYSA-N ; InChI=1/H2O4S2/c1-5(2)6(3)4/h(H,1,2)(H,3,4) Key: GRWZHXKQBITJKP-UHFFFAOYAX;
	SMILES O=S(O)S(=O)O;
Properties
Chemical formula	H2S2O4
Molar mass	130.144 g/mol
Acidity (pKa)	0.35, 2.45
Conjugate base	Dithionite
Related compounds
Related compounds	Oxalic acid; Sodium dithionite; Potassium dithionite
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Dithionous acid is a sulfur oxoacid with the chemical formula H₂S₂O₄. It has not been observed experimentally. It is the conjugate acid of the dithionite dianion, S₂O₄^2-. Dithionite is a well-known reducing agent.