when you titrate oxalate ions with permanganate ions, why arent the iron(III) ions also oxidized?

Question

aaronq · Answer

hm which iron ions?

im guessing that it's because it's at such a high oxidation state already that the electrons are held pretty tight, and a lot of energy is needed to remove them

anonymous · Answer

Well the iron (III) ions correct?

aaronq · Answer

i'm just not sure where they came from, but i guess you omitted that part. Assuming they were in the solution for whatever reason, my answer is still the same as above.

anonymous · Answer

hm would you be able to explain why that would be the answer? I'm not sure i understand :/

aaronq · Answer

yeah no problem.

As you oxidize any atom (remove electrons) you increase the difference between the negative charges (electrons) and positive charges (protons). The result is that there are more positive charges (than negative) and as a result (from electrostatic attraction) the electrons feel an increased "pull" towards the nucleus. The increased "pull" means that the electrons are held closer/tighter and more energy is needed to overcome the attraction to remove any more electrons (oxidize). |dw:1393738788134:dw|

aaronq · Answer

for a quantitative answer you can take a look at reduction potentials and determine the electromotive force needed to further oxidize $Fe^{4+}$, which is (more than likely) higher than the reduction of $Mn^{7+}$.

aaronq · Answer

i mean $Fe^{3+}$

anonymous · Answer

ah ok. That was very helpful, thank you for explaining that to me!

aaronq · Answer

no problem ! hope it's a bit clearer