Cobalt(II) sulfate

From Sciencemadness Wiki
Jump to: navigation, search
Cobalt(II) sulfate
Cobalt sulfate heptahydrate.jpg
IUPAC name
Cobalt(II) sulfate
Other names
Cobalt sulphate
Cobaltous sulfate
Red vitriol
Molar mass 154.996 g/mol (anhydrous)
173.01 g/mol (monohydrate)
263.08 g/mol (hexahydrate)
281.103 g/mol (heptahydrate)
Appearance Red solid (anhydrous, monohydrate)
Pink solid (hexahydrate)
Odor Odorless
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) (decomposes)
Boiling point Decomposes
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 Slightly soluble in ethanol
Insoluble in ammonia, toluene, xylene
Solubility in methanol anhydrous:
1.04 g/100 mL (18 °C)
54.5 g/100 mL (18 °C)
Vapor pressure ~0 mmHg
Safety data sheet AcrosOrganics (monohydrate)
LabChem (hexahydrate)
FisherSci (heptahydrate)
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
424 mg/kg (oral, rat)
Related compounds
Related compounds
Cobalt(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Cobalt(II) sulfate is a red or pink crystalline chemical compound of cobalt with the chemical formula CoSO4. It is commonly encountered in its hydrated form.



Like many transition metal hydrates, cobalt(II sulfate) hexahydrate is a metal aquo complex consisting of octahedral [Co(H2O)6]2+ ions associated with sulfate anions.


Cobalt(II) sulfate is a red (anhydrous, monohydrate) or pink (hexa-, heptahydrate) crystalline solid, soluble in water, with the hydrated form more soluble in methanol than the anhydrous one. It also displays moderate solubility in ethanol, but insoluble in non-polar solvents. It decomposes when heated above 735 °C.


Cobalt sulfate is sold by various suppliers and can also be found on eBay.

Cobalt(II) sulfate, along with most cobalt compounds, is classified as "Substance of very high concern" in the EU and the sale of this compound is regulated, making it difficult to obtain.


Cobalt sulfate can be prepared by reacting cobalt metal, or cobalt oxide/hydroxide with aqueous sulfuric acid. Heating the solution to drive off the water will give the hydrated forms of cobalt sulfate. If anhydrous cobalt(II) sulfate is desired, the hydrated crystals must be heated to 250 °C to drive off the water and then left to cool in a desiccator.


  • Make pigment
  • Make blue glass
  • Grow beautiful red crystals



Cobalt(II) sulfate is harmful and research have shown that exposure to this substance increases the risk of developing cancer.


Cobalt(II) sulfate should be kept in closed bottles, away from moisture. The anhydrous form should be stored in sealed containers.


Cobalt sulfate should be taken to special disposal centers.


Relevant Sciencemadness threads