6L.9

JamieVu_2C
Posts: 108
Joined: Thu Jul 25, 2019 12:16 am

6L.9

(a) Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride. (b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagram).

The half reactions are:
anode: $MnO_{4}^{-}(aq)+8H^{+}(aq)+5e^{-}\rightarrow Mn^{2+}(aq)+4H_{2}O(l)$
cathode: $5Fe^{2+}(aq)\rightarrow 5Fe^{3+}(aq)+5e^{-}$

Which gives the overall reaction:
$MnO_{4}^{-}(aq)+5Fe^{2+}(aq)+8H^{+}(aq)\rightarrow Mn^{2+}(aq)+5Fe^{3+}(aq)+4H_{2}O(l)$

The cell diagram given in the textbook solutions is: Pt(s)|Fe3+(aq), Fe2+(aq)||H+(aq), MnO4-(aq), Mn2+(aq)|Pt(s)
Why is H+ included in the cell diagram? I thought it's usually omitted in the cell diagram unless it's a hydrogen electrode being used since H+ is used to balance the H atoms in the oxidation reaction.

Chem_Mod
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Re: 6L.9

The H+ is included to indicate that you have your reaction taking place in acidic solution. Additionally, your anode and cathode reactions should be switched; oxidation takes place at the anode and reduction takes place at the cathode.