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Topic: Finding the standard reduction potential for half-reactions  (Read 2045 times)

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Offline zygus

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Finding the standard reduction potential for half-reactions
« on: January 06, 2014, 05:32:24 PM »
Hi! I hope everyone had a good holiday!

I've come across a question that is really confusing me. There are a few of them like this on my homework sheet but I'm just not even sure where to start, I hope someone here can give me an idea of how I should begin. Here it is:

Find the standard reduction potential for the half-reaction:         
X+ + é  :rarrow: X  given that:
Cu + 2X+  :rarrow: Cu2+ + 2X  Eo = 0.46 V   


I really wish I could show my steps so far, but I don't even know how to start  :-\

Thank you so much in advance!

Offline mkurek

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Re: Finding the standard reduction potential for half-reactions
« Reply #1 on: January 06, 2014, 09:55:49 PM »
Look at your first reaction with the X's, make it stoichiometrically proportional. And then it's the same way that you "add" net ionic reactions together. The half reactions are just that, so balance them and then add their Eo together.

You might have to look up the half reaction for copper in a reference table, but it should be there as it is a common one. Remember that if the reaction is given as:

A+ + e- -> A and has a Eo of .5 then for you to flip the reaction to A -> A+ + e- you must also flip the reduction potential. So it would be -.5 for the reverse reaction.

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