Dithionic acid

{{Chembox

| Verifiedfields = changed

| verifiedrevid = 477000976

| ImageFile1 = Dithionic-acid-2D.png

| ImageFile2 = Dithionic-acid-3D-balls.png

| ImageAlt2 = Ball-and-stick model of dithionic acid

| IUPACName = dithionic acid{{RedBookRef|page=130}}

| OtherNames = hypodisulfuric acid

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 25128

| InChI = 1/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6)

| InChIKey = RMGVZKRVHHSUIM-UHFFFAOYAM

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6)

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = RMGVZKRVHHSUIM-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|changed|??}}

| CASNo = 14970-71-9

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 9MP5KH5623

| PubChem = 26985

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 29208

| SMILES = O=S(=O)(O)S(=O)(=O)O

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|Section2={{Chembox Properties

| Formula = {{chem2|H2S2O6}}

| MolarMass = 162.14 g mol⁻¹

| ConjugateBase =Dithionate

| pKa = −3.4 (estimated){{cite book|title=Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution|editor-first=D. D.|editor-last=Perrin|edition=2nd|series=IUPAC Chemical Data|issue=29|publisher=Pergamon|location=Oxford|year=1982|publication-date=1984|orig-date=1969|lccn=82-16524|isbn=0-08-029214-3|at=Entry 63}}

}}

|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

}}

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Dithionic acid, {{chem2|H2S2O6}}, is the inorganic compound with the formula {{chem2|H2S2O6}}. It is the doubly protonated derivative of dithionate, a well-characterized dianion. Dithionic acid is mainly observed and characterized as an aqueous solution.{{Greenwood&Earnshaw}} pp. 715-716