Question

In order to prepare one litre normal solution of potassium permanganate , how many grams of potassium permanganate required if the solution is to be used in acid medium for oxidation

Answer 1

When KMnO4 is used in acid medium as oxidiser, 5 electrons are gained by Mn atom. Molecular mass of KMnO4 = 39 + 55 + 16*4 = 158 Here volume and normality is 1 In order to prepare 1 normal solution (1 litre) of potassium permanganate N = (mass/Equivalent mass) * 1/(Volume of solution in litre) 1= mass/(158/5)*1/1 litre {as equivalent mass = molar mass/no.of electrons gained in redox reation) mass = 158/5 = 31.6 g Ans.