Beryllium iodide

Beryllium iodide

Names
Systematic IUPAC name Beryllium iodide
Identifiers
CAS Number	7787-53-3 N
ChemSpider	74209 Y
Jmol interactive 3D	Image
PubChem	82231
InChI InChI=1S/Be.2HI/h;2*1H/q+2;;/p-2 Y Key: JUCWKFHIHJQTFR-UHFFFAOYSA-L Y InChI=1/Be.2HI/h;2*1H/q+2;;/p-2 Key: JUCWKFHIHJQTFR-NUQVWONBAT
SMILES [Be+2].[I-].[I-]
Properties
Chemical formula	BeI2
Molar mass	262.821 g/mol
Appearance	colorless needle-like crystals
Density	4.325 g/cm3
Melting point	480 °C (896 °F; 753 K)
Boiling point	590 °C (1,094 °F; 863 K) [1]
Solubility in water	reacts explosively[1]
Solubility	Slightly soluble in CS2 Soluble in ethanol, diethyl ether[2]
Structure
Crystal structure	orthorhombic
Thermochemistry
Specific heat capacity (C)	71.14 J/(mol × K)
Std molar entropy (So298)	130 J/mol K
Std enthalpy of formation (ΔfHo298)	-192.62 kJ/mol
Gibbs free energy (ΔfG˚)	-210 kJ/mol
Std enthalpy of combustion (ΔcHo298)	19 kJ/mol
Hazards
Main hazards	see Berylliosis
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 0.002 mg/m3 C 0.005 mg/m3 (30 minutes), with a maximum peak of 0.025 mg/m3 (as Be)[3]
REL (Recommended)	Ca C 0.0005 mg/m3 (as Be)[3]
IDLH (Immediate danger	Ca [4 mg/m3 (as Be)][3]
Related compounds
Other anions	Beryllium fluoride Beryllium chloride Beryllium bromide
Other cations	magnesium iodide calcium 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

Beryllium iodide is the chemical compound with the formula BeI₂. It is very hygroscopic and reacts violently with water, forming hydroiodic acid.

Reactions

Beryllium iodide can be prepared by reacting beryllium metal with elemental iodine at temperatures of 500 °C to 700 °C:^[1]

Be + I₂ → BeI₂

Beryllium iodide is also formed when beryllium carbide reacts with hydrogen iodide in the gas phase:

Be₂C + 4 HI → 2 BeI₂ + CH₄

The iodine in beryllium iodide is easily replaced with the other halogens; it reacts with fluorine giving beryllium fluoride and fluorides of iodine, with chlorine giving beryllium chloride, and with bromine giving beryllium bromide. Beryllium iodide also reacts violently with oxidising agents such as chlorate and permanganate to give purple vapour of iodine. The solid and vapor are both flammable in air.^[2]

Applications

Beryllium iodide can be used in the preparation of high-purity beryllium by the decomposition of the compound on a hot tungsten filament.

References

1. 1 2 3 Perry, Dale L.; Phillips, Sidney L. (1995), Handbook of Inorganic Compounds, CRC Press, p. 63, ISBN 0-8493-8671-3, retrieved 2007-12-10 
2. 1 2 Parsons, Charles Lathrop (1909), The Chemistry and Literature of Beryllium, Easton, Pa.: Chemical Publishing, pp. 22–23, retrieved 2007-12-10 
3. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0054". National Institute for Occupational Safety and Health (NIOSH).