Sodium dithionate

Not to be confused with the reducing agent Sodium dithionite, or the sterilizing agent Sodium metabisulfite.
Sodium dithionate
Two sodium cations and one dithionate anion
Ball-and-stick model of the component ions
Names
IUPAC name
Sodium dithionate
Other names
Sodium hyposulfate, Sodium metabisulfate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.682 Edit this at Wikidata
EC Number
  • 231-550-1
UNII
  • InChI=1S/2Na.H2O6S2/c;;1-7(2,3)8(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2 checkY
    Key: CSMWJXBSXGUPGY-UHFFFAOYSA-L checkY
  • InChI=1/2Na.H2O6S2/c;;1-7(2,3)8(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2
    Key: CSMWJXBSXGUPGY-NUQVWONBAI
  • [Na+].[Na+].[O-]S(=O)(=O)S([O-])(=O)=O
Properties
Na2S2O6
Molar mass 206.106 g/mol
Appearance White crystalline powder
Density 2.19 g/cm3
Melting point 190 °C (374 °F; 463 K) (decomposes)
52 °C (dihydrate)
Boiling point 267 °C (513 °F; 540 K) decomposes
6.27 g/100 mL (0 °C)
15.12 g/100 mL (20 °C)
64.74 g/100 mL (100 °C)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Sodium dithionate Na2S2O6 is an important compound for inorganic chemistry. It is also known under names disodium dithionate, sodium hyposulfate, and sodium metabisulfate. The sulfur can be considered to be in its +5 oxidation state.

It should not be confused with sodium dithionite, Na2S2O4, which is a very different compound, and is a powerful reducing agent with many uses in chemistry and biochemistry. Confusion between dithionate and dithionite is commonly encountered, even in manufacturers' catalogues.