Cobalt(III) oxide explained

Cobalt(III) oxide is the inorganic compound with the formula of Co₂O₃. Although only two oxides of cobalt are well characterized, CoO and Co₃O₄, 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:^{[1] [2]}

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.^[3]

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.^[4]

See also

• Cobalt Oxide Nanoparticles

Notes and References

1. Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. p. 1675.
2. Hüttner . Erwin . Beiträge zur Kenntnis der Oxyde des Kobalts . Zeitschrift für anorganische Chemie . Wiley . 27 . 1 . 1901-05-02 . 0863-1778 . 10.1002/zaac.19010270113 . 81–124. de.
3. Shanbhag . Pavitra N. . Biswas . Raju K. . Pati . Swapan K. . Sundaresan . Athinarayanan . Rao . Chinthamani Nagesa Ramachandra . Elusive Co2O3: A Combined Experimental and Theoretical Study . ACS Omega . American Chemical Society (ACS) . 5 . 45 . 2020-11-02 . 2470-1343 . 10.1021/acsomega.0c03397 . 29009–29016. 33225132 . 7675568 .
4. Book: Guoqing . Wu . 无机化学 (Inorganic Chemistry) . 2003 . 高等教育出版社 (Higher Education Press) . People's Republic of China . 9787040115833 . 781 . 4th .