Potassium sulfite
Names
IUPAC name
Potassium sulfite
Other names
E225
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.279 Edit this at Wikidata
UNII
  • InChI=1S/2K.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2 ☒N
    Key: BHZRJJOHZFYXTO-UHFFFAOYSA-L ☒N
  • InChI=1/2K.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2
    Key: BHZRJJOHZFYXTO-NUQVWONBAU
  • [O-]S(=O)[O-].[K+].[K+]
Properties
K2SO3
Molar mass 158.26 g/mol
Appearance White solid
Density 2.49 g/cm3[1]
Soluble
Acidity (pKa) 8
−64.0·10−6 cm3/mol
Hazards
Flash point Non-flammable
Related compounds
Other anions
Potassium sulfate
Potassium selenite
Other cations
Sodium sulfite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Potassium sulfite is the inorganic compound with the formula K2SO3. It is the salt of potassium cation and sulfite anion. It is a white solid that is highly soluble in water. Potassium sulfite is widely used for preserving food and beverages.

Production and reactions

Main article: Sulfite § Reactions

Potassium sulfite is produced by the thermal decomposition of potassium metabisulfite at 190°C:[2]

K2S2O5 → K2SO3 + SO2

See also: Wellman–Lord process

Structure

The structure of solid K2SO3, as assessed by X-ray crystallography. The S-O distances are 1.515 Å, and the O-S-O angles are 105.2°[1]

References

  1. ^ a b Andersen, Leif; Strömberg, Dan; Nevala, H.; Pohjola, S.; Niinistö, Lauri; Volden, Hans V.; Weidlein, Johann; Zingaro, Ralph A. (1986). "The Structure of Potassium Sulfite". Acta Chemica Scandinavica. 40a: 479–480. doi:10.3891/acta.chem.scand.40a-0479.
  2. ^ Johnstone, H. F. (1946). "Sulfites and Pyrosulfites of the Alkali Metals". Inorganic Syntheses. Vol. 2. pp. 162–167. doi:10.1002/9780470132333.ch49. ISBN 9780470132333.