J.R. S. answered 03/12/19
Ph.D. University Professor with 10+ years Tutoring Experience
Assuming the reaction takes place in an acidic environment...
3H2O2 + 2MnO4- + 2H+ → 2MnO2 + 3O2 + 4H2O
From the balanced equation 2 moles MnO4- requires 3 moles H2O2. Using this mole ratio, you can determine the moles of H2O2 needed to react completely with 1 mole of KMnO4.
1 mole KMnO4 x 3 moles H2O2/2 moles KMnO4 = 1.5 moles H2O2 needed