Calcium Bromide Formula

Calcium bromide, also knowns as calcium dibromide, is a chemical compound known for being used in some drilling fluids and food preservatives.

Formula and structure: Calcium bromide chemical formula is CaBr₂ and its molar mass is 199.89 g mol^-1. The compound is commonly found as a hydrated salt with 2 molecules of water and a molar mass of 235.98 g mol^-1. It can also be found as a hexahydrate salt. The structure of the anhydrous salt is formed by one cation Ca²⁺ and two anions Br^-. The structure is an octahedron with Ca centers bound to a total of six anion Br^- through ionic bonds. Its chemical structure can be written as below, in the common representations used for organic molecules.

Occurrence: Calcium bromide is not found in nature.

Preparation: Calcium bromide is prepared from the reaction of calcium oxide with hydrobromic acid. Alternatively, it can be prepared with the reaction of metallic calcium and elemental bromine:

CaO + 2 HBr → CaBr₂ + H₂O

Ca + Br₂ → CaBr₂

Physical properties: Calcium bromide is a white hygroscopic powder in its anhydrous form. Its density is 3.35 g mL^-1. The melting point of the anhydrous salt is 730 °C, while and the boiling point is 1935 °C. Calcium bromide is soluble in water, ethanol, methanol and acetone. It is insoluble in organic solvents.

Chemical properties: Calcium bromide can suffer different reactions. The most known and useful for the chemical industry is the formation of calcium oxide from calcium bromide and oxygen gas:

2 CaBr₂ + O₂ → 2 CaO + 2 Br₂

This reaction is performed at high temperatures and bromine gas is formed as a by-side product.

Uses: Calcium bromide can be used by the food industries as a preservative and as a component of freezing mixtures. It is used as a fire retardant and as a wood preservative. Calcium bromide can also be used as a dehydrating agent.

Health effects / safety hazards: Calcium bromide can irritate eyes, skin and mucous. It is toxic by ingestion. Calcium bromide is not combustible or flammable.