Beryllium iodide

Structural formula
General
Surname	Beryllium iodide
other names	Beryllium (II) iodide Beryllium diiodide
Molecular formula	At 2
Brief description	white needles
External identifiers / databases
CAS number 7787-53-3 EC number 232-119-0 ECHA InfoCard 100.029.199 PubChem 5463524 Wikidata Q421448
properties
Molar mass	262.82 g · mol -1
Physical state	firmly
density	4.325 g cm −3 (20 ° C)
Melting point	510  ° C
boiling point	590 ° C
solubility	reacts violently with water soluble in ethanol
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 350i-330-301-372-319-335-315-317-411 P: ?
Thermodynamic properties
ΔH f 0	−192.5 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Beryllium iodide is the beryllium salt of hydriodic acid with the ratio formula BeI ₂ . The hygroscopic , highly toxic substance forms tetragonal or rhombic white needles and reacts violently with water.

Manufacturing

Beryllium iodide can be made from the elements at 500-700 ° C.

${\displaystyle \mathrm {Be+I_{2}\longrightarrow BeI_{2}} }$

The reaction of beryllium carbide and hydrogen iodide in the gas phase ( nitrogen ) at 600–700 ° C is also possible.

${\displaystyle \mathrm {Be_{2}C+4\ HI\longrightarrow 2\ BeI_{2}+CH_{4}} }$

Wet chemical synthesis is not possible.

properties

Beryllium iodide is a very hygroscopic, white powder that reacts violently with water to form hydrogen iodide.

${\displaystyle \mathrm {BeI_{2}+2\ H_{2}O\longrightarrow Be(OH)_{2}+2\ HI} }$

The iodine in beryllium iodide is easily displaced by other halogens : with fluorine , beryllium fluoride and various iodine fluorides are formed ; with chlorine and bromine , beryllium chloride and beryllium bromide are formed . With oxidizing agents such as potassium permanganate or potassium chlorate , the iodide is oxidized to elemental iodine in a violent reaction. Beryllium iodide exists as a dimer in the vapor phase . At 1200 ° C the steam decomposes into the elements. The enthalpy of formation of beryllium iodide is 21.80 kJ / mol, the enthalpy of evaporation  70.5 kJ / mol. Three different crystal structures are known of beryllium iodide .

Lattice parameters of the various modifications of beryllium iodide

Temperature range	Crystal system	a [Å]	b [Å]	c [Å]
up to 290 ° C	orthorhombic	11.18	5.94	6.04
290 ° C to 370 ° C	orthorhombic	18.0	16.69	11.43
above 370 ° C	tetragonal	5.84	-	5.70

Individual evidence

1. ↑ ^{a b c d e f g h} Dale L. Perry, Sidney L. Phillips: Handbook of inorganic compounds . CRC Press, 1995, ISBN 978-0-8493-8671-8 , p. 63 ( limited preview in Google book search).
2. ^ ^{A b} C. L. Parsons: "The Chemistry and Literature of Beryllium", Chemical Publishing (1909). Full text
3. ↑ Entry on beryllium compounds in the GESTIS substance database of the IFA , accessed on February 1, 2016 (JavaScript required)
4. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the indicated labeling it falls under the group entry beryllium compounds with the exception of aluminum beryllium silicates, and with those specified elsewhere in this Annex in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
5. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-6.
6. ↑ Jean D'Ans, Ellen Lax, Roger Blachnik (ed.): Paperback for chemists and physicists. 3. Elements, inorganic compounds and materials, minerals, Volume 3. 4. Edition, Springer, 1997, ISBN 3-540-60035-3 , p. 334.
7. ^ ^{A b c d e f} Kenneth A. Walsh: "Beryllium chemistry and processing", ASM International (2009). p. 118 ( limited preview in Google Book search)