Potassium bisulfite
IUPAC name
Potassium hydrogen sulfite
Other names
  • Potassium bisulfite
  • potassium bisulphite
  • monopotassium salt
  • monopotassium sulfite
  • potassium hydrosulfite
3D model (JSmol)
ECHA InfoCard 100.028.973 Edit this at Wikidata
EC Number
  • 231-870-1
E number E228 (preservatives)
  • InChI=1S/K.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+1;/p-1
  • OS(=O)[O-].[K+]
Molar mass 120.1561 g/mol
Appearance White crystalline powder
Odor SO2-like
Melting point 190 °C (374 °F; 463 K) (decomposes)
49 g/100mL (20 °C)
115 g/100mL (100 °C)
Solubility Insoluble in alcohol
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 bisulfite (or potassium hydrogen sulfite) is a chemical mixture with the approximately correctly mentioned formula chemical formula KHSO3. Potassium bisulfite in fact is not a real compound,[1] but a mixture of salts that dissolve in water to give solutions composed of potassium ions and bisulfite ions. It is a white solid with an odor of sulfur dioxide. Attempts to crystallize potassium bisulfite yield potassium metabisulfite, K2S2O5.[2]

Potassium bisulfite is used as a sterilising agent in the production of alcoholic beverages.[3] This additive is classified as E number E228 under the current EU-approved food additive legislation.[4]


It is made by the reaction of sulfur dioxide and potassium carbonate. The sulfur dioxide is passed through a solution of the potassium carbonate until no more carbon dioxide is evolved. The solution is concentrated.

See also


  1. ^ Tudela, David; Jenkins, H. Donald B. (2003). "New Methods to Estimate Lattice Energies: Application to the Relative Stabilities of Bisulfite (HSO3) and Metabisulfite (S2O52-) Salts". Journal of Chemical Education. 80 (12): 1482. Bibcode:2003JChEd..80.1482T. doi:10.1021/ed080p1482.
  2. ^ Johnstone, H. F. (1946). "Sulfites and Pyrosulfites of the Alkali Metals". Inorganic Syntheses. Inorganic Syntheses. Vol. 2. pp. 162–167. doi:10.1002/9780470132333.ch49. ISBN 9780470132333.
  3. ^ Barberá, José Jiménez; Metzger, Adolf; Wolf, Manfred (2000). "Sulfites, Thiosulfates, and Dithionitesl Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_477. ISBN 3527306730.
  4. ^ "Approved additives and E numbers". Food Standards Agency. Retrieved 2020-04-07.