How much potassium permanganate is needed to completely oxidize ferrous oxalate?


> 
> Amount of substance of $\ce{MnO4-}$ required to oxidize one mole of ferrous oxalate completely in acid medium will be:
> 
> 
> (a) 7.5 moles
> 
> 
> (b) 0.2 moles
> 
> 
> (c) 0.6 moles
> 
> 
> (d) 0.4 moles
> 
> 
> 


In acidic medium, 1 mole of $\ce{MnO\_4^-}$ accepts 5 moles of electrons. Oxalate is dibasic so will give 2 moles of electrons when oxidized to $\ce{CO2}$.


$\ce{Fe^2+ -> Fe^3+ + e-} $ so total 3 moles of electrons.


$\text{Amount of substance of } \ce{MnO\_4^-}=\frac{3}{5}=0.6$


However, the given answer is 0.4 moles indicating that only oxalate is considered to be oxidized.




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Does $\ce{Fe^{2+} -> Fe^{3+} + e^-} $ actually occur in this reaction?


What would be the net reaction when $\ce{KMnO\_4}$ is used(not just the ions)?




See [here](http://www2.bgsu.edu/departments/chem/faculty/endres/ch128/oxalate.htm).


The "green salt" is $\ce{K3Fe(C2O4)3.3 H2O}$.
\begin{align}
\ce{MnO4- + 8H+ +5e- &-> Mn^2+ + 4 H2O}\\
\ce{C2O4^2- &-> 2 CO2 + 2e-}\\
\ce{2 MnO4^- + 16 H+ + 5 C2O4^2- &-> 2 Mn^2+ + 8 H2O + 10 CO2 (g)}\\
\end{align}


One expects all the oxalate is oxidized to $\ce{CO2}$ and $\ce{Fe(II)}$ is oxidized to $\ce{Fe(III)}$.


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