Cobalt(II) sulfate

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Cobalt(II) sulfate
Cobalt(II) sulfate
CAS number 10124-43-3 YesY
13455-64-0 (monohydrate)
10026-24-1 (heptahydrate)
PubChem 24965
ChemSpider 23338 YesY
UNII H7965X29HX YesY
EC number 233-334-2
ChEBI CHEBI:53470 YesY
RTECS number GG3100000 (anhydrous)
GG3200000 (heptahydrate)
Jmol-3D images Image 1
Molecular formula CoSO4
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 (heptahydrate)
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 (anhydrous)
96.8 °C (heptahydrate)
Boiling point 420 °C (heptahydrate)
Solubility in water anhydrous:
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)
Refractive index (nD) 1.639 (monohydrate)
1.540 (hexahydrate)
1.483 (heptahydrate)
Crystal structure orthorhombic (anhydrous)
monoclinic (monohydrate, heptahydrate)
EU Index 027-005-00-0
EU classification Carc. Cat. 2
Muta. Cat. 3
Repr. Cat. 2
Toxic (T)
Dangerous for the environment (N)
NFPA 704
NFPA 704.svg
Flash point Non-flammable
LD50 424 mg/kg (oral, rat)
Infobox references

Cobalt(II) sulfate is the inorganic compound with the formula CoSO4. It is the divalent cobalt salt of sulfuric acid. The most common form of cobalt sulfate are the hydrates CoSO4.7H2O and CoSO4.H2O. Cobalt(II) sulfate and its hydrates are some of the most commonly available salts of cobalt.


Cobalt(II) sulfate appears as red monoclinic crystals that melt around 100 °C and become anhydrous at 250 °C. It is soluble in water, slightly soluble in ethanol, and especially soluble in methanol. It forms by the reaction of metallic cobalt, its oxide, hydroxide, or carbonate with sulfuric acid. Cobalt is obtained from ores via the sulfate in some cases.[1][2]


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. Upon inhalation of salts, there is some evidence for carcinogenicity.[1]


  1. ^ a b c 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. ^ 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).