[Albert]

Go on: add the iron and balance the chemical equation.

At the moment, the charges aren't balanced yet.

[xstrae]

2MnO₄^- + 16H⁺ + 5C₂O₄^2- +Fe²⁺    ----> 10CO₂ + 2Mn²⁺ + 8H₂O  + Fe³⁺ + e-

is this right?

[Borek]

Go on: add the iron and balance the chemical equation.

Albert - try it by yourself first. That's pretty bad advice.

At the moment, the charges aren't balanced yet.

Yes they are - note konichiwa2x did a mistake in oxalate formula (last digit is a charge).

Edit: I am referring to the earlier reaction, not the one with Fe.

[Albert]

No, it's not.

First of all, I am sure you're aware of the fact that the charges aren't balanced: 16 positive ones among the reagents vs. 6 among the products. They have to be the same.

Then, you must not have electrons. NEVER!  

Don't you want to use half reactions? It's extremely easier.

[Borek]

2MnO₄^- + 16H⁺ + 5C₂O₄ +Fe²⁺    ----> 10CO₂ + 2Mn²⁺ + 8H₂O  + Fe³⁺ + e-

is this right?

No, it is not - for million of reasons. But first of all: it doesn't make sense to try to balance such reaction.

Note, that you have three redox systems here - oxidizer (permanganate) and two reducing agents (oxalate and Fe²⁺). You may separatley balance oxidation of oxalate to carbon dioxide, or of Fe²⁺ to Fe³⁺. Then you can add these ractions in any way you want, multiplying them by any integer nubers you want - and what you will get will be new balanced equation. Does it make sense? No.

Please read my lecture on reaction balacing failures.

[Albert]

Go on: add the iron and balance the chemical equation.

Albert - try it by yourself first. That's pretty bad advice.

I know it Borek.  

I am trying to persuade konichiwa2x to use half reactions method.

[Borek]

Albert - try it by yourself first. That's pretty bad advice.

I know it Borek.  

I am trying to persuade konichiwa2x to use half reactions method.

Half reaction method will not help, idea of balancing system containing more than 2 redox system is faulty.

[xstrae]

allright is the write way to do it by writing down the indivual reactions and adding them?

[Borek]

allright is the write way to do it by writing down the indivual reactions and adding them?

No, as you will have as many reactions looking as properly balanced as you want. Read text at the link provided - there are examples of such reactions.

Or take a look here:

http://www.chemicalforums.com/index.php?topic=8057.msg38533#msg38533

[Borek]

OK, due to popular request (sent in private emails by those ashamed that they don't follow ) here comes detailed explanation prepared (partially) using my EBAS program.

First of all, we have two balanced reactions. Oxidation of oxalate:

2MnO₄^- + 16H⁺ + 5C₂O₄^2- -> 10CO₂ + 2Mn²⁺ + 8H₂O

and oxidation of Fe²⁺

MnO₄^- + 5Fe²⁺ + 8H⁺ -> Mn²⁺ + 5Fe³⁺ + 4H₂O

We can add these two reactions to get:

3MnO₄^- + 24H⁺ + 5C₂O₄^2- + 5Fe²⁺ -> 10CO₂ + 3Mn²⁺ + 12H₂O +  5Fe³⁺

and we get balanced equation - but we can for example add first equation multiplied by 7 to second reaction multiplied by 11 (we will be forced to find out smallest coefficients then) to get:

5MnO₄^- + 40H⁺ + 7C₂O₄^2- + 11Fe²⁺ -> 14CO₂ + 5Mn²⁺ + 20H₂O +  11Fe³⁺

Which one is correct? Note that I can multiply these reaction before adding them by different numbers and I will get as many correctly balanced reactions as I want, making the question even harder, as you will have to select 'correct' equation out of infinite set..

Thing is, none of them describes real situation. Real situation is - there are two, separate reaction taking place simultaneously. We can write speratae, balanced reactions for both of them, but adding them just doesn't make sense.

[xstrae]

ok thanks for explaining that. by the way what is an EBAS?

[Borek]

ok thanks for explaining that. by the way what is an EBAS?

Check my signature.