Calcium sulfite

Calcium sulfite
Names
	IUPAC name Calcium sulfite
	Other names Sulfurous acid, calcium salt (1:1); E226;
Identifiers
CAS Number	10257-55-3 (anhydrous) ; 72878-03-6 (tetrahydrate); 29501-28-8 (hemihydrate);
3D model (JSmol)	Interactive image;
ChemSpider	8329549 ;
ECHA InfoCard	100.030.529
EC Number	233-596-8;
E number	E226 (preservatives)
PubChem CID	10154041;
UNII	7078964UQP ;
CompTox Dashboard (EPA)	DTXSID10883104 ;
	InChI InChI=1S/Ca.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+2;/p-2 ; InChI=1/Ca.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+2;/p-2 Key: GBAOBIBJACZTNA-NUQVWONBAU;
	SMILES [Ca+2].[O-]S([O-])=O;
Properties
Chemical formula	CaSO3
Molar mass	120.17 g/mol
Appearance	White solid
Melting point	600 °C (1,112 °F; 873 K)
Solubility in water	4.3 mg/100 mL (18 °C)
Solubility product (Ksp)	3.1×10−7
Hazards
Flash point	Non-flammable
Related compounds
Other anions	Calcium sulfate
Other cations	Sodium sulfite
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Calcium sulfite, or calcium sulphite, is a chemical compound, the calcium salt of sulfite with the formula CaSO₃·x(H₂O). Two crystalline forms are known, the hemihydrate and the tetrahydrate, respectively CaSO₃·½(H₂O) and CaSO₃·4(H₂O).^[2] All forms are white solids. It is most notable as the product of flue-gas desulfurization.

^ John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.
^ Abraham Cohen; Mendel Zangen (1984). "Studies On Alkaline Earth Sulfites. Structure and Stability of the New Compound Ca₃(SO₃)₂SO₄^.12H₂O and Its Solid Solution In Calcium Sulfite Tetrahydrate". Chemistry Letters. 13 (7): 1051–1054. doi:10.1246/cl.1984.1051.

[crc-1] John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.

[Xray-2] Abraham Cohen; Mendel Zangen (1984). "Studies On Alkaline Earth Sulfites. Structure and Stability of the New Compound Ca₃(SO₃)₂SO₄^.12H₂O and Its Solid Solution In Calcium Sulfite Tetrahydrate". Chemistry Letters. 13 (7): 1051–1054. doi:10.1246/cl.1984.1051.

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