Cobalt(II) nitrate is an inorganic salt with the chemical formula of Co(NO3)2, or CoN2O6. It is also known as cobalt dinitrate. In this ionic compound, a single positive cobalt atom is attracted to two molecules of NO3 to form a reddish, powdery solid. It is formed by cobalt compounds interacting with nitric acid.
Cobalt(II) nitrate is most commonly found in the form of cobalt (II) nitrate hexahydrate. The hexahydrate is a crystal of cobalt(II) nitrate which has surrounded six molecules of water. It is also reddish-brown. The hydrate is soluble in water and with ammonia. It decomposes back into the anhydrous form if heat is applied to it until it reaches water's boiling point.
Both the hexahydrate form and the waterless (anhydrous) form are considered hazardous chemicals. The anhydrous form can cause fires if it comes into contact with other substances. The hexahydrate form is not combustible, but it makes it easier for other materials to burn. The fumes of each form are also toxic. They both cause irritation to the skin and mucus membranes, including the respiratory tract. Inhalation of cobalt(II) nitrate in any form can cause coughing and nausea, and the anhydrous form is associated with increased incidence of lung disease.