Cobalt nitrate

Cobalt(II) nitrate
CAS number 10141-05-6 YesY
10026-22-9 (hexahydrate)
PubChem 25000
ChemSpider 23369 YesY
EC number 233-402-1
RTECS number GG1109000
Jmol-3D images Image 1
Molecular formula Co(NO3)2
Molar mass 182.943 g/mol (anhydrous)
291.03 g/mol (hexahydrate)
Appearance pale red powder (anhydrous)
red crystalline (hexahydrate)
Odor odorless (hexahydrate)
Density 2.49 g/cm3 (anhydrous)
1.87 g/cm3 (hexahydrate)
Melting point

100 °C, decomp (anhydrous)
55 °C (hexahydrate)

Boiling point

100–105 °C, decomp (hexahydrate)
74 °C, decomp (hexahydrate)

Solubility in water hexahydrate: 134 g/100 mL (0 °C)
103.8 g/100 mL (25 °C)
soluble (anhydrous)
Solubility soluble in alcohol, acetone, ethanol, ammonia (hexahydrate)
monoclinic (hexahydrate)
MSDS Cobalt (II) Nitrate MSDS
EU Index 027-009-00-2
EU classification Carc. Cat. 2
Muta. Cat. 3
Repr. Cat. 2
Toxic (T)
Dangerous for the environment (N)
R-phrases R49, R60, R42/43, R68, R50/53
NFPA 704
LD50 434 mg/kg; rat, oral (anhydrous)
691 mg/kg; rat, oral (hexahydrate)
Related compounds
Other anions Cobalt(II) sulfate
Cobalt(II) chloride
Cobalt oxalate
Other cations Iron(III) nitrate
Nickel(II) nitrate
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.


Cobalt(II) nitrate is formed by the interaction of cobalt oxide, hydroxide or carbonate with nitric acid.

Composition and structures

As well as the anhydrous compound Co(NO3)2, there are several hydrates 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.[1] 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.[2]



It is commonly reduced to metallic cobalt or precipitated on various substrates for Fischer-Tropsch catalysis.[3]


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.[4]

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.


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