Sulfurous acid



Sulfurous acid
IUPAC name Sulfurous acid
Properties
Molecular formula H2SO3 (aq)
Molar mass 82.7 g/mol
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Sulfurous acid (or sulphurous acid in British spelling) is the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase.[1] The conjugate bases of this elusive acid are, however, common anions, bisulfite (or hydrogensulfite) and sulfite.

equilibrium:

SO2 + H2O ⇌ HSO3− + H+
Ka = 1.54 × 10−2 dm3 mol−1; pKa = 1.81.

Aqueous solutions of sulfur dioxide, which sometimes are referred to as sulfurous acid are used as chlorine-containing bleaches.

References

  1. ^ D. Sülzle, M. Verhoeven, J. K. Terlouw, H. Schwarz, "Preparation and characterization of sulfurous acid and its radical cation as stable molecules in the gas phase" Angew. Chem. Int. Edn. Engl. 27, 1533-4 (1988). DOI:10.1002/ange.1988100112

See also
 
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