14.17  [ENDORSED]

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Janine Chan 2K
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14.17

Postby Janine Chan 2K » Wed Mar 14, 2018 10:13 pm

"Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride." How do we know to use Fe3+ + e- --> Fe2+ as the half rxn? Why not Fe2+ + 2e- --> Fe or something else?

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Re: 14.17  [ENDORSED]

Postby Chem_Mod » Thu Mar 15, 2018 6:09 pm

The reaction has to begin with Fe2+ ion. Since permanganate ion is an oxidizing agent, that means that for this redox reaction to make sense, the Fe2+ must be oxidized. For the Fe2+ to be oxidized, it must lose an electron. You can't get Fe from that. You can only get Fe3+.

David Zhou 1L
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Re: 14.17

Postby David Zhou 1L » Thu Mar 15, 2018 9:17 pm

For this though, couldn't the Fe be oxidized into Fe2+? Why does it have to be Fe2+ oxidized into Fe3+?

Janine Chan 2K
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Re: 14.17

Postby Janine Chan 2K » Thu Mar 15, 2018 10:35 pm

David Zhou 1L wrote:For this though, couldn't the Fe be oxidized into Fe2+? Why does it have to be Fe2+ oxidized into Fe3+?


I believe it's because we have FeCl2 as a reactant, which would imply the iron on the reactants side must be Fe2+.


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