Need help using Ion Electron Method in acidic conditions.

[thyrgle]

Using the Ion Electron Method (acidic conditions) I need to solve:

MnO₄^- + C₂O₄^2- -> Mn²⁺ + CO₂

So I tried doing:

MnO₄^- -> Mn²⁺

And:

C₂O₄^2- -> CO₂ + 2H₂O

Then I balanced the oxygen atoms with H₂O

MnO₄^- -> Mn²⁺ + 4H₂O

And:

C₂O₄^2- -> CO₂ + 2H₂O

Then I added the hydrogen atoms:

MnO₄^- + 8H⁺ -> Mn²⁺ + 4H₂O

And:

C₂O₄^2- + 4H⁺ -> CO₂ + 2H₂O

Then I tried balancing the electrons and I got -3e for the first equation and -2e for the second. Then I tried combining the two:

2MnO₄^- + 16H⁺ +
3C₂O₄^2- + 12H⁺ -> 2Mn²⁺ + 8H₂O + 3CO₂ + 6H₂O

Cancel out the H⁺ and H₂O:

2MnO₄^- + 28H⁺ +
3C₂O₄^2- -> 2Mn²⁺ + 14H₂O + 3CO₂

I don't know if there is something else I should do (which I suspect there is but I can't tell), and I think I am doing something wrong because my answer didn't turn out right. Any help would be appreciated.

 

[Borek]

C₂O₄^2- -> CO₂ + 2H₂O

You should balance carbon first. H₂O - if needed - should appear in the next step.