Cobalt(II) nitrate
Encyclopedia
Cobalt nitrate is the inorganic
cobalt
(II) salt of nitric acid
, often with various amounts of water. It is more commonly found as a hexahydrate, Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.
s of cobalt(II) nitrate. The various degrees of hydration can be summarised by the general chemical formula
Co(NO3)2·nH2O, where n = 0, 2, 4, 6.
Anhydrous cobalt(II) nitrate adopts a three-dimensional polymeric network structure, with each cobalt(II) atom approximately octahedrally coordinated by six oxygen atoms, each from a different nitrate ion. Each nitrate ion coordinates to three cobalts. The dihydrate is a two-dimensional polymer, with nitrate bridges between Co(II) centres and hydrogen bonding holding the layers together. The tetrahydrate consists of discrete, octahedral [(H2O)4Co(NO3)2] molecules. The hexahydrate is better described as hexaaquacobalt(II) nitrate, [Co(OH2)6][NO3]2, as it consists of discrete [Co(OH2)6]2+ and [NO3]− ions.
s and coordination chemistry. It is also reduced to metallic cobalt or precipitated on various substrates for Fischer-Tropsch catalysis.
Above 55 °C, it dehydrates to the trihydrate and at higher temperatures to the monohydrate.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
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....
(II) salt of nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
, often with various amounts of water. It is more commonly found as a hexahydrate, Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.
Composition and structures
As well as the anhydrous compound Co(NO3)2, there are several hydrateHydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
s of cobalt(II) nitrate. The various degrees of hydration can be summarised by the general chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Co(NO3)2·nH2O, where n = 0, 2, 4, 6.
Anhydrous cobalt(II) nitrate adopts a three-dimensional polymeric network structure, with each cobalt(II) atom approximately octahedrally coordinated by six oxygen atoms, each from a different nitrate ion. Each nitrate ion coordinates to three cobalts. The dihydrate is a two-dimensional polymer, with nitrate bridges between Co(II) centres and hydrogen bonding holding the layers together. The tetrahydrate consists of discrete, octahedral [(H2O)4Co(NO3)2] molecules. The hexahydrate is better described as hexaaquacobalt(II) nitrate, [Co(OH2)6][NO3]2, as it consists of discrete [Co(OH2)6]2+ and [NO3]− ions.
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Uses
The high solubility of cobalt nitrate makes it a common source of cobalt in metal-organic frameworkMetal-organic framework
Metal-Organic Frameworks are crystalline compounds consisting of metal ions or clusters coordinated to often rigid organic molecules to form one-, two-, or three-dimensional structures that can be porous. In some cases, the pores are stable to elimination of the guest molecules and can be used for...
s and coordination chemistry. It is also reduced to metallic cobalt or precipitated on various substrates for Fischer-Tropsch catalysis.
Production
It is derived from reacting metallic cobalt or one of its oxides, hydroxides, or carbonate with nitric acid. It is commonly used in dyes and inks.- CoCO3 + 2 HNO3 + 5 H2O → Co(NO3)2(H2O)6 + CO2
Above 55 °C, it dehydrates to the trihydrate and at higher temperatures to the monohydrate.