Comments on: If the standard reduction potential of a 1/2 cell is positive, which redox rxn is spontaneous when paired? http://alkaline-water.info/142/if-the-standard-reduction-potential-of-a-12-cell-is-positive-which-redox-rxn-is-spontaneous-when-paired/ Learn How To Separate Fact From Fiction Sat, 19 May 2012 13:51:07 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Dr.J http://alkaline-water.info/142/if-the-standard-reduction-potential-of-a-12-cell-is-positive-which-redox-rxn-is-spontaneous-when-paired/comment-page-1/#comment-182 Dr.J Sun, 13 Jun 2010 04:23:31 +0000 http://alkaline-water.info/142/if-the-standard-reduction-potential-of-a-12-cell-is-positive-which-redox-rxn-is-spontaneous-when-paired/#comment-182 Answer is B. For a reaction to be spontaneous, E must be positive for the sum of the oxidation half-reaction and the reduction half-reaction. You have a reduction reaction with a positive Eo. The hydrogen electrode has Eo=0. So combining the reduction reaction written in the forward direction, i.e. as a reduction reaction, with the hydrogen electrode gives Eo>0. Answer is B.

For a reaction to be spontaneous, E must be positive for the sum of the oxidation half-reaction and the reduction half-reaction. You have a reduction reaction with a positive Eo. The hydrogen electrode has Eo=0. So combining the reduction reaction written in the forward direction, i.e. as a reduction reaction, with the hydrogen electrode gives Eo>0.

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