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 used for preserving food and beverages.[2]
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| Names | |
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| IUPAC name
Potassium sulfite
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Other names
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.030.279 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| 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
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Potassium sulfate Potassium selenite |
Other cations
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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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History
editPotassium sulfite was first obtained by Georg Ernst Stahl in the early 18th century,[3] and was therefore known afterwards as Stahl's sulphureous salt. It became the first discovered sulfite and was first properly studied along with other sulfites by French chemists in the 1790s, and it was called sulphite of potash in the early 19th century.[4] Gilles-François Boulduc also discovered the salt in water of Passy in the 1720s.[5]
Production and reactions
editPotassium sulfite is produced by the thermal decomposition of potassium metabisulfite at 190 °C:[6]
- K2S2O5 → K2SO3 SO2
Structure
editThe 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
edit- ^ 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.
- ^ "Potassium sulfite (225)". Codex Alimentarius. Food and Agriculture Organization of the United Nations.
- ^ Coleby, L. J. M. (1938). Studies in the chemical works of Stahl (Doctoral thesis). University of London. pp. 57–63, 181.
- ^ Thomson, Thomas (1807). System of Chemistry.
- ^ Chang, Ku-ming (Kevin) (2014). "Communications of Chemical Knowledge: Georg Ernst Stahl and the Chemists at the French Academy of Sciences in the First Half of the Eighteenth Century". Osiris. 29 (1): 135–157. doi:10.1086/678101. ISSN 0369-7827.
- ^ 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.
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