Oxidation Number

Question

How to calculate oxidation number of MnSO₄ ?

Answer 1

From http://hrsbstaff.ednet.ns.ca/benoitn/chem12/electrochemistry/redox/Assigning%20oxidation%20numbers.pdf:

 

We know that polyatomic ion SO4 carries charge 2- → Mn must be +2

 

There are two ways how to find out oxidation number of S:

 

1. Use polyatomic ion to determine the oxidation number of S: oxygen is -2 and overall ion charge is 2- → S + 4(-2) = -2 S = +6

 

2. Use the whole formula MnSO4: Mn is +2, oxygen is -2 and overall molecule is neutral → (+2) + S + 4(-2) = 0 S = +6