Cobalt(II) nitrate


Cobalt(II) nitrate
Cobalt (II) Nitrate Hexahydrate Sample
Other names
Cobaltous nitrate
Nitric acid, cobalt(2+) salt
  • 10141-05-6 checkY
3D model (JSmol)
  • Interactive image
  • CHEBI:86209 ☒N
  • 23369 checkY
ECHA InfoCard 100.030.353 Edit this at Wikidata
EC Number
  • 233-402-1
  • 25000
RTECS number
  • GG1109000
  • 65W79BFD5V checkY
UN number 1477
  • DTXSID9064970 Edit this at Wikidata
  • InChI=1S/Co.2NO3/c;2*2-1(3)4/q+2;2*-1 checkY
  • InChI=1/Co.2NO3/c;2*2-1(3)4/q+2;2*-1
  • [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O
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 (212 °F; 373 K) decomposes (anhydrous)
55 °C (hexahydrate)
Boiling point 100 to 105 °C (212 to 221 °F; 373 to 378 K) decomposes (anhydrous)[citation needed]
74 °C, decomposes (hexahydrate)
anhydrous:[1] 84.03 g/100 mL (0 °C)
334.9 g/100 mL (90 °C)
soluble (anhydrous)
Solubility soluble in alcohol, acetone, ethanol, ammonia (hexahydrate), methanol 2.1 g/100 mL
monoclinic (hexahydrate)
Safety data sheet Cobalt (II) Nitrate MSDS
GHS pictograms GHS07: Exclamation markGHS09: Environmental hazardGHS09: Environmental hazard
GHS Signal word Danger
H317, H334, H341, H350, H360, H410
P201, P202, P261, P272, P273, P280, P281, P285, P302+P352, P304+P341, P308+P313, P321, P333+P313, P342+P311, P363, P391, P405, P501
NFPA 704 (fire diamond)
Lethal dose or concentration (LD, LC):
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
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cobalt nitrate is the inorganic compound with the formula Co(NO3)2.xH2O. It is cobalt(II)'s salt. The most common form is the hexahydrate Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.[2]

Composition and structures

As well as the anhydrous compound Co(NO3)2, several hydrates of cobalt(II) nitrate exist. These hydrates have the 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.[3] 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.[4] Above 55 °C, the hexahydrate converts to the trihydrate and at higher temperatures to the monohydrate.[2]

Cobalt(II)-nitrate-xtal-2002-CM-3D-SF.png Cobalt(II)-nitrate-dihydrate-xtal-1976-CM-3D-balls.png Cobalt(II)-nitrate-tetrahydrate-xtal-1975-CM-3D-balls.png Hexaaquacobalt(II)-nitrate-xtal-1973-unit-cell-CM-3D-balls.png
Co(NO3)2 Co(NO3)2·2H2O Co(NO3)2·4H2O Co(NO3)2·6H2O


It is commonly reduced to metallic high purity cobalt.[2] It can be absorbed on to various catalyst supports for use in Fischer–Tropsch catalysis.[5] It is used in the preparation of dyes and inks.[6]


The hexahydrate is prepared treating metallic cobalt or one of its oxides, hydroxides, or carbonate with nitric acid:

Co + 4 HNO3 + 4 H2O → Co(H2O)6(NO3)2 + 2 NO2
CoO + 2 HNO3 + 5 H2O → Co(H2O)6(NO3)2
CoCO3 + 2 HNO3 + 5 H2O → Co(H2O)6(NO3)2 + CO2


  1. ^ Perrys' Chem Eng Handbook, 7th Ed
  2. ^ a b c John Dallas Donaldson, Detmar Beyersmann, "Cobalt and Cobalt Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_281.pub2
  3. ^ Tikhomirov, G. A.; Znamenkov, K. O.; Morozov, I. V.; Kemnitz, E.; Troyanov, S. I. (2002). "Anhydrous Nitrates and Nitrosonium Nitratometallates of Manganese and Cobalt, M(NO3)2, NO[Mn(NO3)3], and (NO)2[Co(NO3)4]: Synthesis and Crystal Structure". Z. anorg. allg. Chem. 628 (1): 269–273. doi:10.1002/1521-3749(200201)628:1<269::AID-ZAAC269>3.0.CO;2-P.
  4. ^ Prelesnik, P. V.; Gabela, F.; Ribar, B.; Krstanovic, I. (1973). "Hexaaquacobalt(II) nitrate". Cryst. Struct. Commun. 2 (4): 581–583.
  5. ^ Ernst B, Libs S, Chaumette P, Kiennemann A. Appl. Catal. A 186 (1-2): 145-168 1999
  6. ^ Lewis, Richard J., Sr. (2002). Hawley's Condensed Chemical Dictionary (14th Edition). John Wiley & Sons.