H2O2 acts as oxidising and reducing agent in both acidic as well as in basic medium.
H2O2 as an oxidizing agent (in acidic medium)
2FeSO4(aq)+H2SO4(aq) + H2O2(aq) → Fe2(SO4)3(aq)+2H2O(l)
PbS(s)+4H2O2(aq) → PbSO4(s)+4H2O(l)
In basic medium :
MnSO4(aq)+H2O2(aq) + 2NaOH(aq) → MnO2(s)+Na2SO4(aq) + 2H2O(l)
H2O2 as a reducing agent (in acidic medium)
2KMnO4(aq) + 3H2SO4(aq)+5H2O2(aq) → K2SO4(aq)+2MnSO4(aq) + 8H2O(l)+5O2(g)
In basic medium :
2Fe(aq)3+ + H2O2(aq)+2OH(aq)– → 2Fe(aq)2+ + 2H2O(l)+O2(g)