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]
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IUPAC name
Potassium hydrogen sulfite
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Other names
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Identifiers | |
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3D model (JSmol)
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ChemSpider |
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ECHA InfoCard | 100.028.973 |
EC Number |
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E number | E228 (preservatives) |
PubChem CID
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UNII |
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CompTox Dashboard (EPA)
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Properties | |
KHSO3 | |
Molar mass | 120.1561 g/mol |
Appearance | White crystalline powder |
Odor | SO2-like |
Melting point | 190 °C (374 °F; 463 K) (decomposes) |
49 g/100 mL (20 °C) 115 g/100 mL (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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Infobox references
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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.