Cobalt(III) oxide

Cobalt(III) oxide is the <a href="/facts/Inorganic_compound/TfFfzxSz">inorganic compound</a> with the formula of Co2O3. Although only two oxides of cobalt are well characterized, <a href="/facts/Cobalt(II)_oxide/T7KVtNVB">CoO</a> and <a href="/facts/Cobalt(II,III)_oxide/lp55FCdw">Co3O4</a>, procedures claiming to give Co2O3 have been described. Thus treatment of Co(II) salts such as <a href="/facts/Cobalt(II)_sulfate/7WYVqTA1">cobalt(II) sulfate</a> with an aqueous solution of <a href="/facts/Sodium_hypochlorite/sp99uHHQ">sodium hypochlorite</a> (also known as bleach) gives a black solid:

2CoSO4 + 4NaOH + NaOCl → Co2O3 + 2Na2SO4 + NaCl
Some formulations of the catalyst <a href="/facts/Hopcalite/WXepg1lJ">hopcalite</a> contain "Co2O3".
Some studies have been unable to synthesize the compound, and report that it is theoretically unstable.
It is soluble in cold diluted <a href="/facts/Sulfuric_acid/Wom6fymJ">sulfuric acid</a> and produces Co2[SO4]3, which is blue in aqueous solution.

Co2O3 + 3H2SO4 → Co2[SO4]3 + 3H2O
Cobalt(III) ion is a strong 
<a href="/facts/Oxidizer/1FQzB8pQ">oxidizer</a> in acidic solution, its <a href="/facts/Standard_electrode_potential/YQUhbI6K">standard electrode potential</a> is +1.84V in this situation.

Cobalt(III) oxide open-in-new

Cobalt(III) oxide