Cobalt(II) carbonate
Co2+ CO32−
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_carbonate.jpg?lang=simple)
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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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| UNII |
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CompTox Dashboard (EPA)
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| Properties | ||
| CoCO3 | ||
| Molar mass | 118.941 g/mol | |
| Appearance | pink solid | |
| Density | 4.13 g/cm3 | |
| Melting point | 427 °C (801 °F; 700 K) [3] decomposes before melting to cobalt(II) oxide (anhydrous) 140 °C (284 °F; 413 K) decomposes (hexahydrate) | |
| 0.000142 g/100 mL (20 °C)[1] | ||
Solubility product (Ksp)
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1.0·10−10[2] | |
| Solubility | soluble in acid negligible in alcohol, methyl acetate insoluble in ethanol | |
Refractive index (nD)
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1.855 | |
| Structure | ||
| Rhombohedral (anhydrous) Trigonal (hexahydrate) | ||
| Thermochemistry | ||
| Std enthalpy of formation ΔfH |
−722.6 kJ/mol[3] | |
| Standard molar entropy S |
79.9 J/mol·K[3] | |
| Hazards | ||
| NFPA 704 |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | ||
 verify (what is  ?)
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| Infobox references | ||
Cobalt(II) carbonate is a chemical compound with the formula CoCO3. It is a pink, slightly magnetic powder. It is part of the process used to make cobalt metal from ores. It is also used as a dye and also to make other chemicals called catalysts.[4] Cobalt(II) carbonate also is found as the rare red/pink mineral spherocobaltite.[5]
Preparation and structure
[change | change source]
Structure of solid cobalt(II) carbonate shown with space-filling ions. Color code: red = O, green = Co, blck = C
Cobalt(II) carbonate is made by mixing liquid cobalt(II) sulfate with sodium bicarbonate:
- CoSO4 + 2 NaHCO3 → CoCO3 + Na2SO4 + H2O + CO2
This reaction is used to remove cobalt from a liquid made from its heated ores.[4]
CoCO3 has a structure like calcite. The cobalt atoms are arranged in a shape called octahedral.[6]
Reactions
[change | change source]Like most carbonates of transition metals, cobalt carbonate does not dissolve in water, but reacts easily with mineral acids:
- CoCO3 + 2 HCl + H2O → [Co(H2O)6]Cl2 + CO2
It is used to make many cobalt coordination complexes. One notable complex made from cobalt(II) carbonate is tris(acetylacetonato)cobalt(III), made by reacting with acetylacetone and hydrogen peroxide.[7]
When cobalt carbonate is heated, it behaves like most carbonates during calcining, but the product becomes partly oxidized.
- 6 CoCO3 + O2 → 2 Co3O4 + 6 CO2
The Co3O4 can change back and forth into CoO at high temperatures.[8]
Uses
[change | change source]Cobalt carbonate is used to make other cobalt compounds, including carbonyls and salts. It is added to dietary supplements because the body needs small amounts of cobalt. It is also used to make blue paint for pottery, especially in Delftware.[source?]
Related compounds
[change | change source]There are at least two known cobalt(II) carbonate-hydroxides, Co2(CO3)(OH)2 and Co6(CO3)2(OH)8·H2O.[9]
Spherocobaltite is a somewhat rare natural form of cobalt carbonate. Good samples are found in the Republic of Congo. "Cobaltocalcite" is a type of calcite that contains cobalt. It looks very similar to spherocobaltite.[5]
Sodium tris(carbonato)cobalt(III) is a chemical made of cobalt in the +3 oxidation state. It has three carbonate groups attached to the cobalt. This compound is an example of a cobalt(III) coordination complex, where cobalt is connected to other molecules called ligands.
Safety
[change | change source]Scientists have rarely seen how toxic cobalt carbonate is. Animals, including humans, need small amounts of cobalt, which is part of vitamin B12.[4]
References
[change | change source]- ↑ Haynes, W.M., ed. (2017). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press, Taylor & Francis Group. pp. 4–58. ISBN 978-1-4987-5429-3.
- ↑ "Solubility product constants". Archived from the original on 2012-06-15. Retrieved 2012-05-17.
- ↑ 3.0 3.1 3.2 "Cobalt(II) carbonate".
- ↑ 4.0 4.1 4.2 Template:UllmannDonaldson, John Dallas; Beyersmann, Detmar (2005).
- ↑ 5.0 5.1 "Spherocobaltite: Spherocobaltite mineral information and data". www.mindat.org. Retrieved 7 August 2018. Cite error: Invalid
<ref>tag; name "mindat" defined multiple times with different content - ↑ Pertlik, F. (1986). "Structures of hydrothermally synthesized cobalt(II) carbonate and nickel(II) carbonate". Acta Crystallographica Section C. 42: 4–5. doi:10.1107/S0108270186097524.
- ↑ Bryant, Burl E.; Fernelius, W. Conard (1957). "Cobalt(III) Acetylacetonate". Inorganic Syntheses. pp. 188–189. doi:10.1002/9780470132364.ch53. ISBN 9780470132364.
{{cite book}}: ISBN / Date incompatibility (help) - ↑ El-Shobaky, G. A.; Ahmad, A. S.; Al-Noaim, A. N.; El-Shobaky, H. G. (1996). "Thermal Decomposition of Basic Cobalt and Copper Carbonates". Journal of Thermal Analysis and Calorimetry. 46: 1801. doi:10.1007/BF01980784.
- ↑ Bhojane, Prateek; Le Bail, Armel; Shirage, Parasharam M. (2019). "A Quarter of a Century After its Synthesis and with >200 Papers Based on its Use, 'Co(CO3)0.5(OH)0.11H2O′ Proves to be Co6(CO3)2(OH)8·H2O from Synchrotron Powder Diffraction Data". Acta Crystallographica Section C: Structural Chemistry. 75 (Pt 1): 61–64. doi:10.1107/S2053229618017734. PMID 30601132.