How to make this the same as the equation given from my teacher？

Question

MnO4^- + Fe^+2 →reduction

H2O2 → decomposes

MnO4^- +H2O2 → reduction

The equation given from my teacher

8H^+ +MnO4^- +5Fe^+2 → 5Fe^+2 +Mn^+2 +4H2O

MnO4^- + Fe^+2 → Fe^+3 +Mn^+2

Answer 1

Because you see H+ in the equation, this tells us to balance the reaction in acid (H+). This is a typical redox reaction so we will break it into 2 half reactions (oxidation and reduction)

MnO₄^- ==> Mn²⁺ ... reduction half reaction

MnO₄^- ==> Mn²⁺ + 4H2O ... balanced for Mn and O

MnO₄^- + 8H⁺==> Mn²⁺ + 4H2O ... balanced for Mn, O and H

MnO₄^- + 8H⁺ + 5e- ==> Mn²⁺ + 4H2O ... balanced for Mn, O, H and charge (BALANCED EQUATION)

Fe²⁺ ==> Fe³⁺ ... oxidation half reaction

Fe²⁺ ==> Fe³⁺ + e- ... balanced for Fe and charge (BALANCED EQUATION)

Since the oxidation half reaction has only 1 electron, we multiply it by 5 to equalize the electrons with the reduction half reaction and then combine the two equations.

5Fe²⁺ ==> 5Fe³⁺ + 5e-

MnO₄^- + 8H⁺ + 5e- ==> Mn²⁺ + 4H2O

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MnO₄^- + 8H⁺ + 5Fe²⁺ ==> Mn²⁺ + 4H2O + 5Fe³⁺ ... BALANCED REDOX EQUATION