Cobalt(II) carbonate
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 431006470
| Name = Cobalt(II) carbonate
| ImageFile =
| ImageFile1 =
| ImageFile2 = Cobalt(2) carbonate.jpg
| ImageSize1 = 180px
| ImageName2 = Cobalt(II) carbonate powder
| IUPACName = Cobalt(II) carbonate
| OtherNames = Cobaltous carbonate; cobalt(II) salt
| SystematicName =
| Section1 = {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 513-79-1
| CASNo2_Ref = {{cascite|correct|CAS}}
| CASNo2 = 12602-23-2
| CASNo2_Comment = (cobalt carbonate hydroxide)
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 7H73A68FUV
| UNII2_Ref = {{fdacite|correct|FDA}}
| UNII2 = W58TNI7T29
| UNII2_Comment = (cobalt carbonate hydroxide)
| PubChem = 10565
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 10123
| SMILES = C(=O)([O-])[O-].[Co+2]
| InChI = 1/CH2O3.Co/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2
| InChIKey = ZOTKGJBKKKVBJZ-NUQVWONBAB
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/CH2O3.Co/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = ZOTKGJBKKKVBJZ-UHFFFAOYSA-L
| RTECS =
}}
| Section2 = {{Chembox Properties
| Formula = CoCO3
| Appearance = pink solid
| MolarMass = 118.941 g/mol
| Density = 4.13 g/cm3
| MeltingPtC = 427
| MeltingPt_notes =
decomposes before melting to cobalt(II) oxide (anhydrous)
{{convert|140|C|F K}}
decomposes (hexahydrate)
| BoilingPt =
| Solubility = 0.000142 g/100 mL (20 °C){{cite book |editor1-last=Haynes |editor1-first=W.M. |title=CRC Handbook of Chemistry and Physics |date=2017 |publisher=CRC Press, Taylor & Francis Group |isbn=978-1-4987-5429-3 |pages=4–58 |edition=97th |language=en}}
| SolubleOther = soluble in acid
negligible in alcohol, methyl acetate
insoluble in ethanol
| SolubilityProduct = 1.0·10−10{{cite web |url=http://www.ktf-split.hr/periodni/en/abc/kpt.html |title=Solubility product constants |accessdate=2012-05-17 |url-status=dead |archiveurl=https://web.archive.org/web/20120615020049/http://www.ktf-split.hr/periodni/en/abc/kpt.html |archivedate=2012-06-15 }}
| RefractIndex = 1.855
}}
| Section3 = {{Chembox Structure
| CrystalStruct = Rhombohedral (anhydrous)
Trigonal (hexahydrate)
}}
| Section4 = {{Chembox Thermochemistry
| DeltaHf = −722.6 kJ/mol{{Cite web|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=573|title=Cobalt(II) carbonate}}
}}
| Section5 =
| Section6 =
| Section7 = {{Chembox Hazards
| MainHazards =
| GHSPictograms = {{GHS07}}{{GHS08}}{{Sigma-Aldrich|id=379956|name=Cobalt(II) carbonate|accessdate=2014-05-06}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|302|315|317|319|335|351}}
| PPhrases = {{P-phrases|261|280|305+351+338}}
| FlashPt =
| AutoignitionPt =
| LD50 = 640 mg/kg (oral, rats)
| NFPA-H = 2
| NFPA-F = 0
| NFPA-R = 0
}}
}}
Cobalt(II) carbonate is the inorganic compound with the formula CoCO3. This pink paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts.{{Ullmann|doi=10.1002/14356007.a07_281.pub2| title=Cobalt and Cobalt Compounds | year=2005 | last1=Donaldson | first1=John Dallas | last2=Beyersmann | first2=Detmar | isbn=3527306730 }} Cobalt(II) carbonate also occurs as the rare red/pink mineral spherocobaltite.{{cite web |title=Spherocobaltite: Spherocobaltite mineral information and data |url=http://www.mindat.org/min-3726.html |website=www.mindat.org |accessdate=7 August 2018 |ref=mindat}}
Preparation and structure
:image:Calcium-carbonate-xtal-3D-SF.png
It is prepared by combining solutions of cobalt(II) sulfate and sodium bicarbonate:
:CoSO4 + 2 NaHCO3 → CoCO3 + Na2SO4 + H2O + CO2
This reaction is used in the precipitation of cobalt from an extract of its roasted ores.
CoCO3 adopts a structure like calcite, consisting of cobalt in an octahedral coordination geometry.{{cite journal|title=Structures of hydrothermally synthesized cobalt(II) carbonate and nickel(II) carbonate|author=Pertlik, F.|journal=Acta Crystallographica Section C|year=1986|volume=42|pages=4–5|doi=10.1107/S0108270186097524}}
Reactions
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
It is used to prepare many coordination complexes. The reaction of cobalt(II) carbonate and acetylacetone in the presence of hydrogen peroxide gives tris(acetylacetonato)cobalt(III).{{cite book|doi=10.1002/9780470132364.ch53|chapter=Cobalt(III) Acetylacetonate|title=Inorganic Syntheses|year=1957|last1=Bryant|first1=Burl E.|last2=Fernelius|first2=W. Conard|pages=188–189|isbn=9780470132364}}
Heating the carbonate proceeds in a typical way for calcining, except that the product becomes partially oxidized:
: 6{{nbsp}}CoCO3 + O2 → 2{{nbsp}}Co3O4 + 6{{nbsp}}CO2
The resulting Co3O4 converts reversibly to CoO at high temperatures.{{cite journal |last1=El-Shobaky |first1=G. A. |last2=Ahmad |first2=A. S. |last3=Al-Noaim |first3=A. N. |last4=El-Shobaky |first4=H. G. |year=1996 |title=Thermal Decomposition of Basic Cobalt and Copper Carbonates |journal=Journal of Thermal Analysis and Calorimetry |volume=46 |page=1801 |doi=10.1007/BF01980784}}
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.
Related compounds
At least two cobalt(II) carbonate-hydroxides are known: Co2(CO3)(OH)2 and Co6(CO3)2(OH)8·H2O.{{cite journal |doi=10.1107/S2053229618017734| title=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 | year=2019 | last1=Bhojane | first1=Prateek | last2=Le Bail | first2=Armel | last3=Shirage | first3=Parasharam M. | journal=Acta Crystallographica Section C: Structural Chemistry | volume=75 | issue=Pt 1 | pages=61–64 | pmid=30601132 | s2cid=58657483 | url=https://zenodo.org/record/3755496 }}
The moderately rare spherocobaltite is a natural form of cobalt carbonate, with good specimens coming especially from the Republic of Congo. "Cobaltocalcite" is a cobaltiferous calcite variety that is quite similar in habit to spherocobaltite.
Sodium tris(carbonato)cobalt(III) is a cobalt(III) complex containing three carbonate ligands.
Safety
Toxicity has rarely been observed. Animals, including humans, require trace amounts of cobalt, a component of vitamin B12.
References
{{Reflist}}
External links
- {{Commons category-inline|Cobalt(II) carbonate}}
{{-}}
{{Carbonates}}
{{Cobalt compounds}}