Question

What is the predicted effect of increasing the pH of a redox reaction between hydrogen peroxide and potassium permanganate on the equilibrium position? Explain your answer with balanced chemical equation and the corresponding redox half-reactions.

Answer 1

The redox reaction between hydrogen peroxide  H2O2  and potassium permanganate  KMnO4  can be represented by the following balanced chemical equation:2 KMnO4 + 5 H2O2 + 6 H+  2 Mn2+ + 8 H2O + 5 O2The corresponding redox half-reactions are:Oxidation half-reaction  H2O2 :H2O2  O2 + 2 H+ + 2 e-Reduction half-reaction  KMnO4 :MnO4- + 8 H+ + 5 e-  Mn2+ + 4 H2OWhen the pH of the reaction is increased, the concentration of H+ ions decreases. This affects the reduction half-reaction, as the reduction of MnO4- to Mn2+ requires H+ ions. As the concentration of H+ ions decreases, the reduction half-reaction will be less favored, and the equilibrium position will shift to the left.This means that at higher pH values, the reaction between hydrogen peroxide and potassium permanganate will be less efficient, and the equilibrium position will favor the reactants  H2O2 and KMnO4  over the products  Mn2+, H2O, and O2 .