Cobalt(II) iodide

• Cobaltdiiodid
• Cobalt ( II) iodide

Dark gray - green powder

Fixed

• 5,584 g · cm -3 ( α - )
• 5.45 g · cm -3 ( β - )
• 2.9 g · cm -3 ( hexahydrate)

> 515 ° C

570 ° C.

Soluble in water, Schwefeloxychlorid and phosphorus oxychloride.

Attention

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

Production and representation

α - cobalt iodide can be obtained by the reaction of hydrogen iodide with cobalt.

The hexahydrate can be obtained by reaction of the cobalt ( II) hydroxide and cobalt (II ) carbonate in the aqueous hydroiodic acid.

Properties

α - cobalt iodide is a black graphite-like hygroscopic mass which slowly starts to black green air. It is soluble in water, dilute solutions look red, concentrated solutions at low temperature red, take all the nuances of brown to olive green at higher temperature. Cobalt ( II) iodide has a hexagonal crystal structure of cadmium iodide type with the space group C3m and the lattice parameters a = 396 pm and c = 665 pm. The hexahydrate forms long, dark red crystals that start above 27 ° C to give crystal water and become anhydrous at 130 ° C. In the sublimation of the α - form in a high vacuum, the hygroscopic yellow ocher to green drops deliquescent in moist air β - cobalt iodide is formed. Its solution in water is colorless, but turns pink when heated. The β - form upon heating at 400 ° C with blackening in the α - form via.

Use

Anhydrous cobalt iodide can be used to detect water by a color change to pink in alcohols, ketones, nitriles, and some esters.