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Topic: Predicting Spontaneous Reactions  (Read 3242 times)

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Offline lalex0710

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Predicting Spontaneous Reactions
« on: September 25, 2013, 07:38:10 PM »
I am struggling with the answers my teacher gave me, which contradicted what I have gotten as my results, and I need some clarification or assistance from you guys.

So the question is:

Is Fe2+(aq) capable of reducing Cr3+(aq) to Cr2+(aq)?

I got an answer of yes, since Cr3+ is the oxidizing agent and it is above Fe2+ in the reduction table which indicates it has a higher reduction potential, thus should be able to oxidize Fe2+ or Fe2+ should be capable of reducing Cr3+ since it is lower in reduction potential.

But the answer the teacher gave was no, but I couldn't understand how she arrived at the answer, but I know it has something to do with Fe being multivalent, so it could be referring to Fe3+, but the question asks Fe2+, so Im not sure how she got the answer. Thanks for the help.

Also another similiar question is this: Is Fe2+(aq) capable of reducing Sn2+(aq) to Sn(s)?

Offline Hunter2

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Re: Predicting Spontaneous Reactions
« Reply #1 on: September 26, 2013, 12:59:23 AM »
I would check the redox potentials.

Chromium-II is very unstable and will be oxidized by oxygen of the air.

Offline Borek

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Re: Predicting Spontaneous Reactions
« Reply #2 on: September 26, 2013, 03:00:31 AM »
Cr3+ is the oxidizing agent and it is above Fe2+ in the reduction table

Please list exact standard potentials for both reactions.
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