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| Names | |
|---|---|
| IUPAC name Potassium sulfite | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.030.279 |
| UNII | |
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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 | |
Otheranions | Potassium sulfate Potassium selenite |
Othercations | Sodium sulfite |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Potassium sulfite is theinorganic compound with the formula K2SO3. It is thesalt ofpotassium cation andsulfite anion. It is a white solid that is highly soluble in water. Potassium sulfite is used forpreserving food and beverages.[2]
Potassium sulfite was first obtained byGeorg Ernst Stahl in the early 18th century,[3] and was therefore known afterwards asStahl'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 calledsulphite of potash in the early 19th century.[4]Gilles-François Boulduc also discovered the salt in water ofPassy in the 1720s.[5]
Potassium sulfite is produced by the thermal decomposition ofpotassium metabisulfite at 190 °C:[6]
The structure of solidK2SO3, as assessed byX-ray crystallography. The S-O distances are 1.515 Å, and the O-S-O angles are 105.2°[1]
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