Cobalt (II) iodide

Crystal structure
	__ Co 2+ __ I -
General
Surname	Cobalt (II) iodide
other names	Cobalt diiodide
Ratio formula	CoI 2
Brief description	dark gray-green powder
External identifiers / databases
EC number	239-283-2
ECHA InfoCard	100.035.697
PubChem	419951
Wikidata	Q421250
properties
Molar mass	312.74 g mol −1
Physical state	firmly
density	5.584 g cm −3 (α-); 5.45 g cm −3 (β-); 2.9 g cm −3 (hexahydrate);
Melting point	> 515 ° C
boiling point	570 ° C
solubility	soluble in water, sulfur oxychloride and phosphorus oxychloride.
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 302-312-315-319-332-335
	P: 261-280-305 + 351 + 338
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cobalt (II) iodide is a chemical compound of cobalt and is one of the iodides .

Extraction and presentation

α-Cobalt (II) iodide can be obtained by reacting cobalt with hydrogen iodide .

{\ displaystyle \ mathrm {Co + 2 \ HI \ longrightarrow CoI_ {2} + H_ {2}}}

The hexahydrate can be obtained by reacting cobalt (II) hydroxide or cobalt (II) carbonate in aqueous hydroiodic acid.

properties

α-Cobalt (II) iodide is a black, graphite-like hygroscopic mass that slowly turns black-green in air. It is soluble in water, whereby the diluted solutions look red, concentrated solutions turn red at low temperatures and all shades from brown to olive green at higher temperatures. Cobalt (II) iodide has a trigonal crystal structure of the cadmium iodide type with the space group P 3 m 1 (space group no.164) and the lattice parameters a = 396 pm and c = 665 pm. The hexahydrate forms long, dark red crystals that begin to give off water of crystallization above 27 ° C and become anhydrous at 130 ° C. The sublimation of the α-form in a high vacuum produces the hygroscopic ocher yellow β-cobalt (II) iodide that dissolves into green droplets in moist air. Its solution in water is colorless, but turns pink when heated. When heated at 400 ° C., the β-form changes to the α-form while turning black. In addition to the hexahydrate form, a di- and a tetrahydrate are also known. Template: room group / 164

use

Anhydrous cobalt (II) iodide can be used to detect water by changing color to pink in alcohols , ketones , nitriles and some esters .

Individual evidence

↑ ^a ^b ^c ^d ^e data sheet Cobalt (II) iodide, anhydrous, powder, 99.999% from Sigma-Aldrich , accessed on July 3, 2012 ( PDF ).
↑ ^a ^b ^c ^d ^e ^f Georg Brauer: Handbook of preparative inorganic chemistry. Walter de Gruyter 1994, ISBN 3-432-87823-0 , p. 222 ( limited preview in the Google book search).
↑ american elements : Cobalt Iodide: AMERICAN ELEMENTS Supplier & Tech Info

↑ D. Nicholls: The Chemistry of Iron, Cobalt and Nickel: Comprehensive Inorganic Chemistry . Elsevier, 2013, ISBN 978-1-4831-4643-0 , pp. 1070 ( limited preview in Google Book Search).

↑ WLF Armarego, Christina Li Lin Chai: Purification of Laboratory Chemicals. Elsevier 2003, ISBN 0-750-67571-3 , p. 26 ( limited preview in Google book search).

[Sigma-1] ↑ ^a ^b ^c ^d ^e data sheet Cobalt (II) iodide, anhydrous, powder, 99.999% from Sigma-Aldrich , accessed on July 3, 2012 ( PDF ).

[brauer-2] ↑ ^a ^b ^c ^d ^e ^f Georg Brauer: Handbook of preparative inorganic chemistry. Walter de Gruyter 1994, ISBN 3-432-87823-0 , p. 222 ( limited preview in the Google book search).

[americanelements-3] rican elements : Cobalt Iodide: AMERICAN ELEMENTS Supplier & Tech Info

[D._Nicholls-4] D. Nicholls: The Chemistry of Iron, Cobalt and Nickel: Comprehensive Inorganic Chemistry . Elsevier, 2013, ISBN 978-1-4831-4643-0 , pp. 1070 ( limited preview in Google Book Search).

[5] WLF Armarego, Christina Li Lin Chai: Purification of Laboratory Chemicals. Elsevier 2003, ISBN 0-750-67571-3 , p. 26 ( limited preview in Google book search).