Potassium sulfite

Potassium sulfite
Names

IUPAC name Potassium sulfite
Other names E225
Identifiers
CAS Number	10117-38-1^Y
3D model (JSmol)	Interactive image
ChemSpider	23332^N
ECHA InfoCard	100.030.279
PubChem CID	24958
UNII	015KZC652E^N
CompTox Dashboard (EPA)	DTXSID80889532
InChI InChI=1S/2K.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2+1;/p-2^N Key: BHZRJJOHZFYXTO-UHFFFAOYSA-L^N InChI=1/2K.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2+1;/p-2 Key: BHZRJJOHZFYXTO-NUQVWONBAU
SMILES [O-]S(=O)[O-].[K+].[K+]
Properties
Chemical formula	K₂SO₃
Molar mass	158.26 g/mol
Appearance	White solid
Density	2.49 g/cm³^[1]
Solubility in water	Soluble
Acidity (pK_a)	8
Magnetic susceptibility (χ)	−64.0·10⁻⁶ cm³/mol
Hazards
Flash point	Non-flammable
Related compounds
Other anions	Potassium sulfate Potassium selenite
Other cations	Sodium sulfite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references

Chemical compound

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]

Production and reactions

Potassium sulfite is produced by the thermal decomposition of potassium metabisulfite at 190 °C:^[3]

K₂S₂O₅ → K₂SO₃ + SO₂

The 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]

^ ^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.
^ 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.