Hello, I came across this question and couldn't resolve it using the oxidation number method.

 

Fe²⁺ + H₂O₂ --> Fe³⁺ + H₂O

 

 

Using half equations to balance it out, I got the right answer, though using the oxidation number method I got an alternate answer.

 

 

Now the Iron is being oxidized, and the O₂ is being reduced, with the oxidation number difference of 1 for both elements...

 

What am I missing? The difference of oxidation number for oxygen should be 2... but I can't see how that works...

You're missing a few O^2- ions in your equation. Your redox half reactions are not complete. Also, the charge is not the same on both sides of your equation. You have +2 on the left, and +3 on the right side. Charge must be equal on both sides.

 

The iron is likely to be FeO or Fe₂O₃, not just Fe²⁺ or Fe³⁺, which indicates that there is another half reaction you didn't write down yet.

You're missing a few O^2- ions in your equation. Your redox half reactions are not complete. Also, the charge is not the same on both sides of your equation. You have +2 on the left, and +3 on the right side. Charge must be equal on both sides.

 

The iron is likely to be FeO or Fe₂O₃, not just Fe²⁺ or Fe³⁺, which indicates that there is another half reaction you didn't write down yet.

 

 

So, your saying that I'm missing something in that given equation? But it was given to us like that , the teacher's didn't state any problems within the question itself...