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Cobalt(II) bromide
Encyclopedia
Cobalt bromide (CoBr2) is an inorganic compound used primarily as a catalyst in some processes.
, cobalt(II) bromide appears as green crystals. The hexahydrate loses four waters of crystallization molecules at 100°C forming the dihydrate:
Further heating to 130°C Produces the anhydrous form:
The anhydrous form will then melts at 678°C. At higher temperatures, cobalt(II) bromide reacts with oxygen
, forming cobalt(II,III) oxide
and bromine
vapor.
:
Anhydrous cobalt(II) bromide may be prepared through the direct reaction of elemental cobalt
and liquid bromine
.
. Bromide is also mildly toxic.
Properties
When anhydrousAnhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
, cobalt(II) bromide appears as green crystals. The hexahydrate loses four waters of crystallization molecules at 100°C forming the dihydrate:
- CoBr2.6H2O → CoBr2.2H2O + 4H2O
Further heating to 130°C Produces the anhydrous form:
- CoBr2.4H2O → CoBr2
The anhydrous form will then melts at 678°C. At higher temperatures, cobalt(II) bromide reacts with oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, forming cobalt(II,III) oxide
Cobalt(II,III) oxide
Cobalt oxide is inorganic compound with the formula Co3O4. It is one of two well characterized cobalt oxides. It is a black antiferromagnetic solid...
and bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
vapor.
Preparation
Cobalt(II) bromide can be prepared as a hydrate by the reaction of cobalt hydroxide with hydrobromic acidHydrobromic acid
Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...
:
- Co(OH)2(s) + 2HBr(aq) → CoBr2.6H2O(aq)
Anhydrous cobalt(II) bromide may be prepared through the direct reaction of elemental cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
and liquid bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
.
Uses
Cobalt(II) bromide may be used as a catalyst in the oxidation of some organic compounds with cobalt(III).Health issues
Exposure to large amounts of cobalt(II) can cause cobalt poisoningCobalt poisoning
Cobalt poisoning is intoxication caused by excessive levels of cobalt in the body. Cobalt is an essential element for health in animals in minute amounts as a component of Vitamin B12. A deficiency of cobalt, which is very rare, is also potentially lethal, leading to pernicious anemia. However in...
. Bromide is also mildly toxic.