Cobalt(II) carbonate
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| Names | |||
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| IUPAC name
Cobalt(II) carbonate
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| Other names
Cobaltous carbonate; cobalt(II) salt
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| Identifiers | |||
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3D model (JSmol)
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| ChemSpider | |||
| ECHA InfoCard | 100.007.428 | ||
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |||
| CoCO3 | |||
| Appearance | red/ pink crystals (anhydrous) pink, violet, red crystalline powder (hexahydrate) | ||
| Density | 4.13 g/cm3 | ||
| Melting point | 427 °C (801 °F; 700 K) [2] decomposes before melting to cobalt(II) oxide (anhydrous) 140 °C (284 °F; 413 K) decomposes (hexahydrate) | ||
| negligible | |||
Solubility product (Ksp)
|
1.0·10−10[1] | ||
| Solubility | soluble in acid negligible in alcohol, methyl acetate insoluble in ethanol | ||
Refractive index (nD)
|
1.855 | ||
| Structure | |||
| Rhombohedral (anhydrous) Trigonal (hexahydrate) | |||
| Thermochemistry | |||
Std molar
entropy (S⦵298) |
79.9 J/mol·K[2] | ||
Std enthalpy of
formation (ΔfH⦵298) |
−722.6 kJ/mol[2] | ||
Gibbs free energy (ΔfG⦵)
|
-651 kJ/mol[2] | ||
| Hazards | |||
| GHS labelling: | |||
  [3]
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| Warning | |||
| H302, H315, H317, H319, H335, H351[3] | |||
| P261, P280, P305+P351+P338[3] | |||
| NFPA 704 (fire diamond) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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640 mg/kg (oral, rats) | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cobalt(II) carbonate is the inorganic compound with the formula CoCO3. This reddish paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts.[4] Commercially available pale violet basic cobalt carbonate, with the formula CoCO3(Co(OH)x(H2O)y (CAS 12069-68-0).[5]
Preparation and properties
It is prepared by heating cobaltous sulfate with a solution of sodium bicarbonate.
Heating the carbonate, i.e. calcining, proceeds in the usual way:
- 3 CoCO3 + 1/2 O2 → Co3O4 + 3 CO2
The resulting Co3O4 converts reversibly to CoO at high temperatures.[6] Like most transition metal carbonates, cobalt carbonate is insoluble in water, but is readily attacked by mineral acids:
- CoCO3 + 2 HCl + 5 H2O → [Co(H2O)6]Cl2 + CO2
Uses
Cobalt carbonate is a precursor to cobalt carbonyl and various cobalt salts. It is a component of dietary supplements since cobalt is an essential element. It is a precursor to blue pottery glazes, famously in the case of Delftware.
Safety
The compound is harmful if swallowed, and irritating to eyes and skin.
References
- ^ http://www.ktf-split.hr/periodni/en/abc/kpt.html
- ^ a b c d http://chemister.ru/Database/properties-en.php?dbid=1&id=573
- ^ a b c Sigma-Aldrich Co., Cobalt(II) carbonate. Retrieved on 2014-05-06.
- ^ John Dallas Donaldson, Detmar Beyersmann, "Cobalt and Cobalt Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_281.pub2
- ^ Cobalt(II) carbonate also occurs as the rare mineral spherocobaltite, which occurs as pink/red trigonal crystals with a specific gravity of 4.13g/cm3Spherocobaltite www.mindat.org
- ^ G.A. El-Shobaky, A.S. Ahmad, A.N. Al-Noaimi and H.G. El-Shobaky Journal of Thermal Analysis and Calorimetry 1996, Volume 46, Number 6 , pp.1801-1808. online abstract
External links
