Potassium bisulfite

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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 approximate 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[edit]


  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 978-3527306732.
  4. ^ "Approved additives and E numbers". Food Standards Agency. Retrieved 2020-04-07.