Dithionic acid
![]() | |
![]() | |
Names | |
---|---|
IUPAC name dithionic acid[1] | |
Other names hypodisulfuric acid | |
Identifiers | |
CAS Number |
|
3D model (JSmol) |
|
ChEBI |
|
ChemSpider |
|
PubChem CID |
|
UNII |
|
CompTox Dashboard (EPA) |
|
InChI
| |
| |
Properties | |
Chemical formula | H2S2O6 |
Molar mass | 162.14 g mol−1 |
Acidity (pKa) | −3.4 (estimated)[2] |
Conjugate base | Dithionate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). ![]() ![]() ![]() Infobox references |
Chemical compound
Dithionic acid, H2S2O6, is the inorganic compound with the formula H2S2O6. It is the doubly protonated derivative of dithionate, a well-characterized dianion. Dithionic acid is mainly observed and characterized as an aqueous solution.[3]
Synthesis
Dithionates can be made by oxidizing a sulfite (from the +4 to the +5 oxidation state), but on a larger scale they are made by oxidizing a cooled aqueous solution of sulfur dioxide with manganese dioxide:
- 2 MnO2 + 3 SO2 → MnS2O6 + MnSO4
The manganese dithionate solution formed can then be converted to dithionate salts of other metals by metathesis reactions:
- Ba2+ (aq) + MnS2O6 (aq) + MnSO4 (aq) → BaSO4 (s)↓ + BaS2O6 · 2 H2O (aq)
Concentrated solutions of dithionic acid can subsequently be obtained treating a barium dithionate solution with sulfuric acid:
- BaS2O6 (aq) + H2SO4 (aq) → H2S2O6 (aq) + BaSO4 (s)↓
See also
- Sodium dithionite
- Hypophosphoric acid, the phosphorus equivalent.
References
- ^ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. p. 130. Electronic version.
- ^ Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 63. ISBN 0-08-029214-3. LCCN 82-16524.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. pp. 715-716
- v
- t
- e
- H3AsO3
- H3AsO4
- HArF
- HAt
- HSO3F
- H[BF4]
- HBr
- HBrO
- HBrO2
- HBrO3
- HBrO4
- HCl
- HClO
- HClO2
- HClO3
- HClO4
- HCN
- HCNO
- H2CrO4/H2Cr2O7
- H2CO3
- H2CS3
- HF
- HFO
- HI
- HIO
- HIO2
- HIO3
- HIO4
- HMnO4
- H2MnO4
- H2MoO4
- HNC
- NaHCO3
- HNCO
- HNO
- HNO2
- HNO3
- H2N2O2
- HNO5S
- H3NSO3
- H2O
- H2O2
- H2O3
- H2O4
- H2O5
- H3PO2
- H3PO3
- H3PO4
- H4P2O7
- H5P3O10
- H2[PtCl6]
- H2S
- H2S2
- H2Se
- H2SeO3
- H2SeO4
- H4SiO4
- H2[SiF6]
- HSCN
- HNCS
- H2SO3
- H2SO4
- H2SO5
- H2S2O3
- H3O
- H2S2O6
- H2S2O7
- H2S2O8
- CF3SO3H
- H2Te
- H2TeO3
- H6TeO6
- H4TiO4
- H2Po
- H[Co(CO)4]