Calculate the equivalent weight of KMnO4 and MnO2. And explain it.

Molecular mass of KMnO4 = 158 gm
In acidic medium, no. of electrons involved n is:
 ​MnO4- + 8H+ +5e- ---> Mn+2 + 4H2O
So, equivalent mass = molar mass/ electrons involved= 158/ 5 = 31.6 gm/ equivalent

In strongly basic medium
​MnO4- + 1e- ---> MnO42-
So, n = 1 , equivalent weight = 158/1 = 158gm/ qeuivalent

In neutral medium
MnO4- + 4H2O +3e- ---> MnO2 + 4OH- 
Here, n = 3 so, equivalent weight = 158/3 = 52.66 gm/equivalent

For, MnO2 (molar mass = 87) , here  n = 3
So, equivalent weight = molar mass/ 3 = 87/3 = 29 gm/equivalent.

  • 14

KMnO4

n factor = 5 in acidic medium

n factor = 3 in Neutral medium

n factor = 1 in basic medium

and according to the need we find equivalent weight

MnO2

here KMnO4 changes to MnO2 so , n factor of Mn here is 3

now we can calculate equivalent mass

  • 4
What are you looking for?