Calcium iodide

Calcium iodide
Names
	IUPAC name calcium iodide
Identifiers
CAS Number	10102-68-8 ; 13640-62-5 (tetrahydrate) ;
3D model (JSmol)	Interactive image;
ChemSpider	59629 ;
ECHA InfoCard	100.030.238
EC Number	233-276-8;
PubChem CID	66244;
RTECS number	EV1300000;
UNII	8EKI9QEE2H ;
CompTox Dashboard (EPA)	DTXSID2064945 ;
	InChI InChI=1S/Ca.2HI/h;21H/q+2;;/p-2 Key: UNMYWSMUMWPJLR-UHFFFAOYSA-L ; InChI=1/Ca.2HI/h;21H/q+2;;/p-2 Key: UNMYWSMUMWPJLR-NUQVWONBAC;
	SMILES [Ca+2].[I-].[I-];
Properties
Chemical formula	CaI2
Molar mass	293.887 g/mol (anhydrous) ; 365.95 g/mol (tetrahydrate)
Appearance	white solid
Density	3.956 g/cm3 (anhydrous)[1]
Melting point	779 °C (1,434 °F; 1,052 K) (anhydrous) [2]
Boiling point	1,100 °C (2,010 °F; 1,370 K) [2]
Solubility in water	64.6 g/100 mL (0 °C) ; 66 g/100 mL (20 °C) ; 81 g/100 mL (100 °C)
Solubility	soluble in acetone and alcohols
Magnetic susceptibility (χ)	-109.0·10−6 cm3/mol
Structure
Crystal structure	Rhombohedral, hP3
Space group	P-3m1, No. 164
Coordination geometry	octahedral
Hazards
NFPA 704 (fire diamond)	0 2 1
Related compounds
Other anions	calcium fluoride; calcium chloride; calcium bromide
Other cations	beryllium iodide; magnesium iodide; strontium iodide; barium iodide
	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

Calcium iodide (chemical formula CaI₂) is the ionic compound of calcium and iodine. This colourless deliquescent solid is a salt that is highly soluble in water. Its properties are similar to those for related salts, such as calcium chloride. It is used in photography.[1] It is also used in cat food as a source of iodine.

Reactions

Henri Moissan first isolated pure calcium in 1898 by reducing calcium iodide with pure sodium metal:[3]

CaI₂ + 2 Na → 2 NaI + Ca

Calcium iodide can be formed by treating calcium carbonate, calcium oxide, or calcium hydroxide with hydroiodic acid:[4]

CaCO₃ + 2 HI → CaI₂ + H₂O + CO₂

Calcium iodide slowly reacts with oxygen and carbon dioxide in the air, liberating iodine, which is responsible for the faint yellow color of impure samples.[5]

2 CaI₂ + 2 CO₂ + O₂ → 2 CaCO₃ + 2 I₂

References

Turner, Jr., Francis M., ed. (1920), The Condensed Chemical Dictionary (1st ed.), New York: Chemical Catalog Co., p. 127, retrieved 2007-12-08
R. J. Lewis (1993), Hawley's Condensed Chemical Dictionary 12th edition
Mellor, Joseph William (1912), Modern Inorganic Chemistry, New York: Longmans, Green, and Co, p. 334, 6909989325689, retrieved 2007-12-08
Gooch, Frank Austin; Walker, Claude Frederic (1905), Outlines of Inorganic Chemistry, New York: Macmillan, p. 340, retrieved 2007-12-08
Jones, Harry Clary (1906), Principles of Inorganic Chemistry, New York: Macmillan, p. 365, retrieved 2007-12-08

[cond-1] Turner, Jr., Francis M., ed. (1920), The Condensed Chemical Dictionary (1st ed.), New York: Chemical Catalog Co., p. 127, retrieved 2007-12-08

[haw93-2] R. J. Lewis (1993), Hawley's Condensed Chemical Dictionary 12th edition

[3] Mellor, Joseph William (1912), Modern Inorganic Chemistry, New York: Longmans, Green, and Co, p. 334, 6909989325689, retrieved 2007-12-08

[4] Gooch, Frank Austin; Walker, Claude Frederic (1905), Outlines of Inorganic Chemistry, New York: Macmillan, p. 340, retrieved 2007-12-08

[5] Jones, Harry Clary (1906), Principles of Inorganic Chemistry, New York: Macmillan, p. 365, retrieved 2007-12-08