Question

When potassium permanganate is titrated against ferrous ammonium sulphate the equivalent weight of potassium permanganate is?

Answer 1

Let's assume that Molecular Weight of Mohr's Salt is 'M'.

KMnO4 will oxidise Fe2+ ion to Fe3+ and will itself reduce to Mn2+

However, Fe2+ changes it's oxidation state by 1. Hence N-Factor or Valence Factor of Fe in Mohr's Salt is 1 and hence Equivalent Weight=Molecular Weight/N-Factor = M/1 = 1.

Instead of FeSO4, if someone asks you what's the n-factor of KMnO4, then it's answer is 5 and hence it's equivalent weight is one fifth of it's molecular weight.

Answer 2

Answer:

m/5

Explanation:

molecular weight of Mohr's salt is M

kmno4 will oxidise into fe2+ ion into fe3+

and will reduce itself into mn2+

fe2+ oxidation

equivalent wt = molecular wt / n factor

m/1=1

n factor of kmno4 is 5 hence

Answer : m/5