Cobalt(II) oxide is an inorganic compound that has been described as an olive-green[3] or gray[4] solid. It is used extensively in the ceramics industry as an additive to create blue-colored glazes and enamels, as well as in the chemical industry for producing cobalt(II) salts. A related material is cobalt(II,III) oxide, a black solid with the formula Co3O4.
-oxide-3D-vdW.png) | |
| Names | |
|---|---|
| IUPAC name Cobalt(II) oxide | |
| Other names Cobaltous oxide Cobalt monoxide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.013.777 |
| EC Number |
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PubChem CID | |
| RTECS number |
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| UNII | |
| UN number | 3288 |
CompTox Dashboard (EPA) | |
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| Properties | |
| CoO | |
| Molar mass | 74.9326 g/mol |
| Appearance | olive or gray powder |
| Odor | odorless |
| Density | 6.45 g/cm3 [1] |
| Melting point | 1,933 °C (3,511 °F; 2,206 K) |
| insoluble in water[2] | |
| +4900.0·10−6 cm3/mol | |
| Structure | |
| cubic, cF8 | |
| Fm3m, No. 225 | |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H302, H317, H410 | |
| P260, P280, P284, P301+P310+P330, P304+P340+P310, P342+P311, P403+P233 | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 202 mg/kg |
| Safety data sheet (SDS) | ICSC 1551 |
| Related compounds | |
Other anions | Cobalt(II) sulfide Cobalt(II) hydroxide |
Other cations | Iron(II) oxide Nickel(II) oxide |
Related compounds | Cobalt(II,III) oxide Cobalt(III) oxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Structure and properties
CoO crystals adopt the periclase (rock salt) structure with a lattice constant of 4.2615 Å.[5]
It is antiferromagnetic below 289 K.[6]
Preparation
Cobalt(II) oxide is prepared by oxidation of cobalt powder with air or by thermal decomposition of cobalt(II) nitrate or the carbonate.[3][4]
Cobalt(II,III) oxide decomposes to cobalt(II) oxide at 950 °C:[7]
- 2 Co3O4 → 6 CoO + O2
It may also be prepared by precipitating the hydroxide, followed by thermal dehydration:[citation needed]
- CoX2 + 2 KOH → Co(OH)2 + 2 KX
- Co(OH)2 → CoO + H2O
Reactions
As can be expected, cobalt(II) oxide reacts with mineral acids to form the corresponding cobalt salts:[citation needed]
- CoO + 2 HX → CoX2 + H2O
Applications
Cobalt(II) oxide has for centuries been used as a coloring agent on kiln fired pottery. The additive provides a deep shade of blue named cobalt blue. The band gap (CoO) is around 2.4 eV.[citation needed]It also is used in cobalt blue glass.