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Topic: Predicting redox reactions  (Read 1955 times)

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Offline xtheunknown0

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Predicting redox reactions
« on: October 03, 2011, 09:52:39 PM »
Hello,

I'm puzzled by how we decide which pairs (sometimes there are more than 2 reactions possible at a cathode?) of equations in the electrochemical series will happen.

For instance, why doesn't 2H2O(l) + 4Na+ (aq) => O2(g) + 4H+ (aq) occur?

xtheunknown0

Offline Elite_Troll42

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Re: Predicting redox reactions
« Reply #1 on: October 03, 2011, 10:26:53 PM »
Look at a standard reductions table. The reaction is more spontaneous the more positive Eo is. so, when you have a pair of things that species that might be reduced, the one with the higher reduction potential (more positive/less negative) will get reduced and the lower will get oxidized. Your reaction will not occur because Na+ has a highly negative reduction potential so water can't reduce it.

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