Magnesium iodide

• Magnesium ( II) iodide
• Magnesiumdiiodid

White, odorless solid

Fixed

4.43 g · cm -3

634 ° C ( decomposition)

Very well in water (1480 g · l-1 at 18 ° C )

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Magnesium iodide ( MgI2 ) is a chemical compound, the magnesium salt of hydriodic acid. It occurs, except as anhydrous Anhydrous, also in several hydrate forms MgI2 · (H2O) x, so as hexa-and octahydrate on.

Production and representation

Magnesium iodide can be obtained directly from the elements magnesium and iodine under heating and the absence of air or oxygen:

Also possible is the production of magnesium by reaction with mercury ( II) iodide.

Properties

Magnesium iodide is a colorless, odorless, highly water- soluble, hexagonal crystalline solid that under dry inert gas (usually argon) must be retained because of its hygroscopic nature and sensitivity to air. With water it forms various hydrates ( MgI2 · 6 H2O, MgI2 · 8 H2O). In air, it gradually decomposes under browning to elemental iodine, magnesium oxide and water.

Magnesium iodide belongs, like many other halides, and hydroxides of divalent metals, or sulfides and tellurides of tetravalent metals to CdI2 type structure (a = 4.14 Å, c = 6.88 Å ) which have all of the same crystal structure. It is extremely hygroscopic. From its aqueous solution crystallizes at ordinary temperature, the octahydrate, above 43 ° C the hexahydrate is stable.