| IUPAC name
| Other names
|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)
|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)|
| 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|| 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)|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|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).
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.