- Acidity of hydrogen peroxide
Hydrogen peroxide is a very weak acid, so the peroxide of metal can be regarded as its salt. As a weak binary acid, the ionization equation of hydrogen peroxide can be expressed as H █ O ∈+H ∈ O ≈ H ｜ O ∈+HO ∈; HO₂¯+H₂O≒H₃O⁺+ O₂⊃2; ¯。 Hydrogen peroxide (H ∈ O ∈) and water are very weak electrolytes, but they are easier to ionize than water. At 298K, its first ionization constant is K=1.55 × 10¯⊃1; ⊃2;。
- Oxidation of hydrogen peroxide
Hydrogen peroxide has strong oxidizability. It can oxidize sulfur ions, iodine ions, bromine ions, ferrous ions, sulfite, etc. In alkaline environment,+2 valence manganese ions can be oxidized to+4 valence manganese (manganese dioxide); Oxidation of+3 valent chromium to+6 valent chromium. It can also oxidize many organic substances, such as formaldehyde to formic acid. The reduction product of hydrogen peroxide under acidic conditions is H ∈ O, and the reduction product under neutral or alkaline conditions is hydroxide, often referred to as “green oxidant”.
H₂O₂+2KI+2HCl=2KCl+I₂+2H₂O；
2Fe⊃2; ⁺+H₂O₂+2H⁺=2Fe⊃3; ⁺+2H₂O；
H₂O₂+H₂S = S↓+2H₂O；
H₂O₂+ SO₂= H₂SO₄；
Cu+H₂O₂+2HCl=CuCl₂+2H₂O；
The lead white [basic lead carbonate] in the oil painting will react with hydrogen sulfide in the air to produce black lead sulfide, which can be converted into white lead sulfate by hydrogen peroxide washing.