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Postby KaleenaJezycki_1I » Tue Mar 03, 2020 8:37 pm

For this problem you are asked to write the half reactions of potassium permanganate and Iron (III) Chloride. How are you supposed to know that the Iron is going to go to go from Iron 2+ to Iron 3+ I understand that Iron 3+ comes from the (III) in "Iron chloride" but how do you know that it isn't Fe3+ --> Fe2+ ? Same with the order of the Potassium Permanganate. I'm referring to the step by step in edition 7 of the solutions manual for reference.

Julie Park 1G
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Re: 6L.9

Postby Julie Park 1G » Tue Mar 03, 2020 10:32 pm

The problem mentions that this is an acidified solution of potassium permanganate and Iron (III) Chloride.
With this information, I wonder if the H+ in the left side of the half-reaction symbolizes the protons existing in the acidified solution while the 5e- represent how acids gain electrons (according to the Lewis definition of acids). This is the cathode half reaction (cathode --> reduction --> gain in electrons)

This might provide a reasoning to the order of potassium permanganate, therefore meaning that the half-reaction involving iron would have to be reversed.

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