Calcium bromide

Crystal structure
__ Ca 2+      __ Br -
General
Surname	Calcium bromide
other names	Calcium dibromide
Ratio formula	CaBr 2
Brief description	white solid
External identifiers / databases
CAS number 7789-41-5 (anhydrous) 71626-99-8 (hydrate) 22208-73-7 (dihydrate) 13477-28-6 (hexahydrate) EC number 232-164-6 ECHA InfoCard 100.029.240 PubChem 24608 ChemSpider 23010 Wikidata Q409739
properties
Molar mass	199.88 g mol −1
Physical state	firmly
density	3.353 g cm −3 (anhydrate) 2.295 g cm −3 (hexahydrate)
Melting point	730 ° C
boiling point	806-812 ° C
solubility	good in water (1420 g l −1 at 20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 318 P: 280-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Calcium is the calcium salt of hydrobromic acid ( bromides ). It is a colorless solid that slowly turns yellow in air.

Extraction and presentation

Calcium bromide can be obtained by reacting calcium carbonate , calcium oxide or calcium hydroxide with hydrogen bromide .

${\displaystyle \mathrm {CaO+2\ HBr\longrightarrow CaBr_{2}+H_{2}O} }$

An alternative is the reaction of the calcium salts with bromine and a reducing agent such as formic acid or formaldehyde .

${\displaystyle \mathrm {CaCO_{3}+Br_{2}+HCOOH\longrightarrow CaBr_{2}+H_{2}O+2\ CO_{2}} }$

properties

Calcium bromide, like calcium chloride and strontium chloride , crystallizes in the calcium chloride structure , which is similar to the rutile structure . In the gaseous state it forms linear molecules. A crystalline hexahydrate is also known which crystallizes trigonally in the space group P 321 (space group no. 150) with the lattice parameters a = 8.164  Å and c = 4.016 Å.

The compound slowly turns yellow in air as elemental bromine is formed. Calcium bromide is soluble in water and methanol , but only slightly soluble in ether and chloroform .

use

Calcium bromide is used for the production of photo plates , as a medicine , in wood preservatives and in flame retardants .

Individual evidence

1. ↑ Calcium bromide data sheet from Sigma-Aldrich , accessed on March 15, 2011 ( PDF ).
2. ↑ ^{a b c d} data sheet calcium bromide from AlfaAesar, accessed on June 9, 2009 ( PDF )(JavaScript required) .
3. ↑ ^{a b c d e} Yoffe, D .; Frim, R .; Ukeles, SD; Dagani, MJ; Barda, HJ; Benya, TJ; Sanders, DC: Bromine Compounds , in: Ullmanns Enzyklopädie der Technischen Chemie , Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 2013; doi : 10.1002 / 14356007.a04_405.pub2 .
4. ↑ ^{a b} Entry on calcium bromide in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
5. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1241.
6. ↑ A. Leclaire, MM Borel: Le dichlorure et le dibromure de calcium hexahydrates. In: Acta Crystallographica , B33, 1977, pp. 2938-2940, doi: 10.1107 / S0567740877009881 .
7. ↑ Entry on calcium bromide. In: Römpp Online . Georg Thieme Verlag, accessed on January 3, 2015.