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Names | |
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IUPAC name dithionic acid [1] | |
Other names hypodisulfuric acid | |
Identifiers | |
3D model (JSmol) | |
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Properties | |
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). |
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]
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:
The manganese dithionate solution formed can then be converted to dithionate salts of other metals by metathesis reactions:
Concentrated solutions of dithionic acid can subsequently be obtained treating a barium dithionate solution with sulfuric acid: