Cobalt(II) nitrate
Chemical compound From Wikipedia, the free encyclopedia
Cobalt nitrate is the inorganic compound with the formula Co(NO3)2.xH2O. It is a cobalt(II) salt. The most common form is the hexahydrate Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.[2]
_Nitrate.jpg) Hexahydrate | |
| Names | |
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| Other names
Cobaltous nitrate Nitric acid, cobalt(2+) salt | |
| Identifiers | |
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3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.030.353 |
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PubChem CID |
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| UNII | |
| UN number | 1477 |
CompTox Dashboard (EPA) |
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| Properties | |
| Co(NO3)2(H2O)6 | |
| Molar mass | 291.03 g/mol (hexahydrate) 182.943 g/mol (anhydrous) |
| Appearance | pale red powder (anhydrous) red crystalline (hexahydrate) |
| Odor | odorless |
| Density | 1.87 g/cm3 (hexahydrate) 2.49 g/cm3 (anhydrous) |
| Melting point | 100 °C (212 °F; 373 K) decomposes (anhydrous) 55 °C (hexahydrate) |
| Boiling point | 100 to 105 °C (212 to 221 °F; 373 to 378 K) decomposes (anhydrous)[citation needed] 74 °C, decomposes (hexahydrate) |
| anhydrous:[1] 84.03 g/100 mL (0 °C) 334.9 g/100 mL (90 °C) soluble (anhydrous) | |
| Solubility | soluble in alcohol, acetone, ethanol, ammonia (hexahydrate), methanol 2.1 g/100 mL |
| Structure | |
| monoclinic (hexahydrate) | |
| Hazards | |
| GHS labelling: | |
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| Danger | |
| H317, H334, H341, H350, H360, H410 | |
| P201, P202, P261, P272, P273, P280, P281, P285, P302+P352, P304+P341, P308+P313, P321, P333+P313, P342+P311, P363, P391, P405, P501 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
434 mg/kg; rat, oral (anhydrous) 691 mg/kg; rat, oral (hexahydrate) |
| Safety data sheet (SDS) | Cobalt (II) Nitrate MSDS |
| Related compounds | |
Other anions |
Cobalt(II) sulfate Cobalt(II) chloride Cobalt oxalate |
Other cations |
Iron(III) nitrate Nickel(II) nitrate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Composition and structures
As well as the anhydrous compound Co(NO3)2, several hydrates of cobalt(II) nitrate exist. These hydrates have the chemical formula Co(NO3)2·nH2O, where n = 0, 2, 4, 6.
Anhydrous cobalt(II) nitrate adopts a three-dimensional polymeric network structure, with each cobalt(II) atom approximately octahedrally coordinated by six oxygen atoms, each from a different nitrate ion. Each nitrate ion coordinates to three cobalts.[3] The dihydrate is a two-dimensional polymer, with nitrate bridges between Co(II) centres and hydrogen bonding holding the layers together.[4] The tetrahydrate consists of discrete, octahedral [(H2O)4Co(NO3)2] molecules. The hexahydrate is better described as hexaaquacobalt(II) nitrate, [Co(OH2)6][NO3]2, as it consists of discrete [Co(OH2)6]2+ and [NO3]− ions.[5] Above 55 °C, the hexahydrate converts to the trihydrate and at higher temperatures to the monohydrate.[2]
Co(NO3)2
Co(NO3)2·2H2O
Co(NO3)2·4H2O
Co(NO3)2·6H2O
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Uses and reactions
It is commonly reduced to metallic high purity cobalt.[2] It can be absorbed on to various catalyst supports for use in Fischer–Tropsch catalysis.[6] It is used in the preparation of dyes and inks.[7]
Cobalt(II) nitrate is a common starting material for the preparation of coordination complexes such as cobaloximes,[8] carbonatotetraamminecobalt(III),[9] and others.[10]
Production
The hexahydrate is prepared treating metallic cobalt or one of its oxides, hydroxides, or carbonate with nitric acid:
- Co + 4 HNO3 + 4 H2O → Co(H2O)6(NO3)2 + 2 NO2
- CoO + 2 HNO3 + 5 H2O → Co(H2O)6(NO3)2
- CoCO3 + 2 HNO3 + 5 H2O → Co(H2O)6(NO3)2 + CO2
References
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