Cobalt(II) chloride
Cobalt(II) chloride, also known as cobaltous chloride and cobalt dichloride, is a chemical compound. It contains cobalt in its +2 oxidation state. Its chemical formula is CoCl2. It contains cobalt and chloride ions.
| Cobalt(II) chloride | |
|---|---|
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| IUPAC name | Cobalt(II) chloride |
| Other names | Cobaltous chloride Cobalt dichloride Muriate of cobalt[1] |
| Identifiers | |
| CAS number | |
| PubChem | |
| EC number | 231-589-4 |
| ChEBI | CHEBI:35696 |
| RTECS number | GF9800000 |
| SMILES | Cl[Co]Cl |
| Properties | |
| Molecular formula | CoCl2 |
| Molar mass | 129.839 g/mol (anhydrous) 165.87 g/mol (dihydrate) 237.93 g/mol (hexahydrate) |
| Appearance | blue crystals (anhydrous) violet-blue (dihydrate) rose red crystals (hexahydrate) |
| Density | 3.356 g/cm3 (anhydrous) 2.477 g/cm3 (dihydrate) 1.924 g/cm3 (hexahydrate) |
| Melting point |
726 °C, 999 K, 1339 °F |
| Boiling point | |
| Solubility in water | 43.6 g/100 mL (0 °C) 45 g/100 mL (7 °C) 52.9 g/100 mL (20 °C) 105 g/100 mL (96 °C) |
| Solubility | 38.5 g/100 mL (methanol) 8.6 g/100 mL (acetone) soluble in ethanol, pyridine, glycerol |
| +12,660·10−6 cm3/mol | |
| Structure | |
| Crystal structure | CdCl2 structure |
| Coordination geometry |
hexagonal (anhydrous) monoclinic (dihydrate) Octahedral (hexahydrate) |
| Hazards | |
| NFPA 704 |
0
3
0
|
| Flash point | Non-flammable |
| Related compounds | |
| Other anions | Cobalt(II) fluoride Cobalt(II) bromide Cobalt(II) iodide |
| Other cations | Rhodium(III) chloride Iridium(III) chloride |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
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Properties
Cobalt(II) chloride is normally found in the red (or pink) form. The red form has water in it. It can be heated to turn it into the blue form, without water. The blue form will absorb water from the air and turn red again.
A different blue form is made when cobalt(II) chloride is reacted with a chemical compound that has chloride in it. Hydrochloric acid works the best, but sodium chloride can be used too. When it is heated, it turns more blue than when it is cooled.
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for an example. Cobalt chloride can be used to test for chloride ions in this way.
It can be oxidized to cobalt(III) compounds, although cobalt(III) chloride does not exist. If it is made, it just drops a Cl from CoCl3, making CoCl2 (cobalt(II) chloride) again.
Preparation
The anhydrous (without water) blue form can be made by reacting cobalt with chlorine. The hydrated (with water) red form can be made by reacting cobalt(II) oxide or cobalt(II) hydroxide with hydrochloric acid.
Uses
It is used to place cobalt into other chemical compounds. It can be used to make other cobalt compounds. It is the most common cobalt compound in the lab.
Safety
It is a weak oxidizing agent, too weak to ignite things. Cobalt compounds are toxic in large quantities, like any other transition metal compounds. They are not toxic like lead or mercury compounds, though.
Cobalt(II) Chloride Media
Subunit of CoCl2(H2O)2 lattice.
The structure of a cobalt(IV) coordination complex with the norbornyl anion
The deep blue colour of this moisture indicating silica gel is due to cobalt chloride. When hydrated the colour changes to a light pink/purple.
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References
- ↑ "Cobalt muriate, CAS Number: 7646-79-9". www.chemindustry.com. Archived from the original on 28 May 2019. Retrieved 19 April 2018.