Description
Calcium bromide has the chemical formula CaBr2. It
was first prepared by Pfeiffer, Klossmann and Angern
in 1924. It is a deliquescent salt that has the form of
colorless hexagonal crystals that are soluble in water and absolute alcohol. Its molecular weight is 199.90 g/
mol for the anhydride. When strongly heated in air,
calcium bromide will produce CaO (lime) and Br2. It
is generally obtained as the dihydrate, CaBr2·2H2O,
in the form of a white crystalline powder. A hexahydrate,
CaBr2·6H2O, is also known. Anhydrous calcium
bromide is obtained by dehydration (250°C, vacuum)
of the dihydrate CaBr2·2H2O. On contact with hot
surfaces or flames, CaBr2 decomposes forming
bromine as a toxic and corrosive fume. It also reacts
with strong acids to produce corrosive fumes of
bromine.
In its solid anhydrous state, it is a white powder.
CaBr2 can be found in drilling muds, neuroses medication,
freezing mixtures, food preservatives, photography
and fire retardants. The anhydride has a melting point
of 730°C and a boiling point of 810°C where it decomposes.
Its density is 3.41 g/cm3. It is moderately soluble
in water at 142 g/100 ml of water.
Chemical Properties
Calciumbromide, CaBr2, is a colorless crystalline solid with a melting point of 765°C. It is deliquescent and is soluble in water and absolute alcohol. Calcium bromide is used in medicine. Calcium bromide(hydrated), CaBr2·3H20, has a meiting point of 80.5℃.
Preparation
CaBr2·2H2O has a melting point of 38°C where it
dissolves in its own waters of hydration. Its density is
2.290 g/cm3. It can be prepared by reaction in solution
with HBr on the carbonate:
CaCO3 (solid)＋HBr (liq)→CaBr2 (liq)＋ CO2 (gas)
An improved method for producing calcium bromide
has been developed by reacting hydrogen bromide with
calcium hydroxide in the presence of water.
