Complexes with titanyl sulfate and with chromate
With colorless titanyl sulfate, a deep yellow titanium peroxo complex is formed.
TiO2+ + H2O2 -> [TiO2]2+ + H2O
This reaction can also be used to detect dissolved titanium ions.
Cr2O72- + 4 H2O2 -> 2 [CrO5(OH)]– + 3 H2O
In the same way, a deep blue colored chromium-peroxo-hydroxo complex is formed from dichromate ions.
In both cases it is not an oxidation, but a complex formation reaction!
Catalyzed decomposition reactions (disproportionation)
If solid manganese dioxide is added, the mixture will foam up vigorously. Oxygen is formed.
2 H2O2 -> 2 H2O + O2
Reduction of potassium permanganate
Compared to strong oxidizing agents, H2O2 acts as a reducing agent. A good example is the reaction of permanganate ions with hydrogen peroxide.
2 MnO4– + 5 H2O2 + 6 H+ -> 2 Mn2+ + 8 H2O + 5 O2
Oxidation of manganese (II) to manganese dioxide
Hydrogen peroxide is, however, better known for its oxidizing effect. In alkaline solutions, it oxidizes manganese (II) to manganese (IV), which precipitates as manganese dioxide (manganese oxide hydroxide).
Mn2+ + H2O2 + 2 OH– -> MnO(OH) + 2 H2O
Oxidation of iodide
H2O2 releases elemental iodine from iodide. It is important that the solution must be acidic, otherwise the oxidizing power of H2O2 is not sufficient.
H2O2 + 2 H+ + 2I– -> 2 H2O + I2
Oxidation of lead sulfide
Black lead sulfide is oxidized to colorless lead sulfate in a neutral solution.
PbS + 4 H2O2 -> PbSO4 + 4 H2O