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Lindsey Chheng 1E
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Postby Lindsey Chheng 1E » Sun Mar 01, 2020 7:21 pm

9.a) Write balanced half reactions for the redox reaction of an acidified solution of potassium permanganate and iron (II) chloride.

I'm trying to write the overall reaction in order to figure out the half reactions, and I got 2KMnO4 + FeCl2 ⟶ 2KCl + Fe(MnO2)2. Based on this, I know K+ and Cl- will cancel and be in solution as aqueous ions, but I don't get how Fe or Mn are supposed to change oxidation states. Pretty sure my overall equation is wrong to begin with because the half reactions - after taking into consideration the acidified solution - are supposed to be
anode: Fe2+ ⟶ Fe3+ + e-
cathode: MnO4- + 8H+ + 5e- ⟶ Mn2+ + 4H2O

Can someone please help me solve this problem?

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Re: 6L.9a

Postby Chem_Mod » Mon Mar 02, 2020 4:21 pm

I am not too sure what your exact issue with the question is, but those are the correct half reactions

To balance, multiply the iron oxidation half reaction by 5:
5Fe2+ --> 5e- + 5Fe3+

Combine with the permanganate reaction
MnO4- + 8H+ + 5e- ⟶ Mn2+ + 4H2O
5Fe2+ --> 5e- + 5Fe3+
MnO4- + 8H + 5Fe2+ ⟶ Mn2+ + 4H2O+ 5Fe3+

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