Cobalt(III) oxide is the inorganic compound with the formula of Co2O3. Although only two oxides of cobalt are well characterized, CoO and Co3O4,[4] procedures claiming to give Co2O3 have been described. Thus treatment of Co(II) salts such as cobalt(II) sulfate with an aqueous solution of sodium hypochlorite (also known as bleach) gives a black solid:[5][6]
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| Names | |
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| IUPAC name
cobalt(III) oxide, dicobalt trioxide
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| Other names
cobaltic oxide, cobalt sesquioxide
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| Identifiers | |
3D model (JSmol)
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| ECHA InfoCard | 100.013.779 |
| EC Number |
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PubChem CID
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| RTECS number |
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CompTox Dashboard (EPA)
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| Properties | |
| Co2O3 | |
| Molar mass | 165.8646 g/mol |
| Appearance | red powder |
| Density | 5.18 g/cm3 [2] |
| Melting point | 895[3] °C (1,643 °F; 1,168 K) |
| negligible | |
| +4560.0·10−6 cm3/mol | |
| Structure | |
| Corundum, hR30 | |
| R3c, No. 167 | |
| Thermochemistry | |
Std enthalpy of
formation (ΔfH⦵298) |
-577 kJ/mol |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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toxic |
| GHS labelling: | |
 
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| Warning | |
| H302, H317, H351, H410 | |
| P280 | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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- 2CoSO4 + 4NaOH + NaOCl → Co2O3 + 2Na2SO4 + NaCl
Some formulations of the catalyst hopcalite contain "Co2O3".
Some studies have been unable to synthesize the compound, and report that it is theoretically unstable.[7]
It is soluble in cold diluted sulfuric acid and produces Co2[SO4]3, which is blue in aqueous solution.
- Co2O3 + 3H2SO4 → Co2[SO4]3 + 3H2O
Cobalt(III) ion is a strong oxidizer in acidic solution, its standard electrode potential is +1.84V in this situation.[8]
See also
editReferences
edit- ^ Sigma-Aldrich product page
- ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
- ^ "1308-04-9 CAS MSDS (COBALT(III) OXIDE BLACK) Melting Point Boiling Point Density CAS Chemical Properties".
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. p. 1675.
- ^ Hüttner, Erwin (1901-05-02). "Beiträge zur Kenntnis der Oxyde des Kobalts". Zeitschrift für anorganische Chemie (in German). 27 (1). Wiley: 81–124. doi:10.1002/zaac.19010270113. ISSN 0863-1778.
- ^ Shanbhag, Pavitra N.; Biswas, Raju K.; Pati, Swapan K.; Sundaresan, Athinarayanan; Rao, Chinthamani Nagesa Ramachandra (2020-11-02). "Elusive Co2O3: A Combined Experimental and Theoretical Study". ACS Omega. 5 (45). American Chemical Society (ACS): 29009–29016. doi:10.1021/acsomega.0c03397. ISSN 2470-1343. PMC 7675568. PMID 33225132.
- ^ Guoqing, Wu (2003). 无机化学 (Inorganic Chemistry) (4th ed.). People's Republic of China: 高等教育出版社 (Higher Education Press). p. 781. ISBN 9787040115833.