Cobalt(II) sulfate

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Cobalt(II) sulfate
Cobalt(II) sulfate Xray
IUPAC name
Cobalt(II) sulfate
3D model (JSmol)
ECHA InfoCard 100.030.291
EC Number
  • 233-334-2
RTECS number
  • GG3100000 (anhydrous)
    GG3200000 (heptahydrate)
Molar mass 154.996 g/mol (anhydrous)
173.01 g/mol (monohydrate)
263.08 g/mol (hexahydrate)
281.103 g/mol (heptahydrate)
Appearance reddish crystalline (anhydrous, monohydrate)
pink salt (hexahydrate)
Odor odorless (heptahydrate)
Density 3.71 g/cm3 (anhydrous)
3.075 g/cm3 (monohydrate)
2.019 g/cm3 (hexahydrate)
1.948 g/cm3 (heptahydrate)
Melting point 735 °C (1,355 °F; 1,008 K)
36.2 g/100 mL (20 °C)
38.3 g/100 mL (25 °C)
84 g/100 mL (100 °C)
60.4 g/100 mL (3 °C)
67 g/100 mL (70 °C)
Solubility anhydrous:
1.04 g/100 mL (methanol, 18 °C)
insoluble in ammonia
54.5 g/100 mL (methanol, 18 °C)
+10,000·10−6 cm3/mol
1.639 (monohydrate)
1.540 (hexahydrate)
1.483 (heptahydrate)
orthorhombic (anhydrous)
monoclinic (monohydrate, heptahydrate)
Safety data sheet JT Baker MSDS
Carc. Cat. 2
Muta. Cat. 3
Repr. Cat. 2
Toxic (T)
Dangerous for the environment (N)
R-phrases (outdated) R49, R60, R22, R42/43, R68, R50/53
S-phrases (outdated) S53, S45, S60, S61
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
424 mg/kg (oral, rat)
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(II) sulfate is any of the inorganic compounds with the formula CoSO4(H2O)x. Usually cobalt sulfate refers to the hydrate CoSO4.7H2O, which is one of the most commonly available salts of cobalt.

Properties, preparation, and structure[edit]

Cobalt(II) sulfate heptahydrate appears as red monoclinic crystals that liquify around 100 °C and become anhydrous at 250 °C. It is soluble in water, slightly soluble in ethanol, and especially soluble in methanol. The salts are paramagnetic.

It forms by the reaction of metallic cobalt, its oxide, hydroxide, or carbonate with aqueous sulfuric acid.[1]

The hexahydrate is a metal aquo complex consisting of octahedral [Co(H2O)6]2+ ions associated with sulfate anions.[2]


Cobalt is obtained from ores via the sulfate in many cases.[1][3]

Hydrated cobalt(II) sulfate is used in the preparation of pigments, as well as in the manufacture of other cobalt salts. Cobalt pigment is used in porcelains and glass. Cobalt(II) sulfate is used in storage batteries and electroplating baths, sympathetic inks, and as an additive to soils and animal feeds. For these purposes, the cobalt sulfate is produced by treating cobalt oxide with sulfuric acid.[1]

Health issues[edit]

Cobalt is essential for most higher forms of life, but more than a few milligrams each day is harmful. Rarely have poisonings resulted from cobalt compounds.[4] Upon inhalation of salts, there is some evidence for carcinogenicity.[1]

See also[edit]


  1. ^ a b c d John D. Donaldson, Detmar Beyersmann "Cobalt and Cobalt Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a07_281.pub2
  2. ^ Elerman, Y. "Refinement of the crystal structure of CoSO4*6H2O" Acta Crystallographica Section C 1988, volume 44, p599-p601. doi:10.1107/S0108270187012447
  3. ^ Rarely, cobalt(II) sulfate is found in form of few crystallohydrate minerals, occurring among oxidation zones containing primary Co minerals (like skutterudite or cobaltite). These minerals are: biebierite (heptahydrate), moorhouseite (Co,Ni,Mn)SO4.6H2O, aplowite (Co,Mn,Ni)SO4.4H2O and cobaltkieserite (monohydrate).
  4. ^ 11.1.5 The unusual type of myocardiopathy recognized in 1965 and 1966 in Quebec (Canada), Minneapolis (Minnesota), Leuven (Belgium), and Omaha (Nebraska) was associated with episodes of acute heart failure (e/g/, 50 deaths among 112 beer drinkers).