If given the following what would the reduction potential be on the new scale in which the reaction of water in base has an E^o"_(red) = 0.000 V?

Suppose there were a new scale for expressing electrode potentials in which the standard potential for the reduction of water in base:

2H_2O(l) + 2e^(-) -> H_2(g) + 2OH^(-)(aq)

is assigned an E^o"_(red) value of 0.000 V. In current standard reduction tables, the following reaction has a standard reduction potential of 1.34 V.

M^(3+)(aq) + 3e^(-) -> M(s)

1 Answer
Truong-Son N.
Dec 16, 2016

Write out a number line. The original E_"red"^@ was -"0.8277 V", when in reference to the Standard Hydrogen Electrode, which is normally the one at "0.0000 V".

If we offset this reduction of water in base forward by +"0.8277 V", we offset the Standard Hydrogen Electrode forward by that much, as well as every remaining reduction potential.

Normal Reduction Potentials (V)

" "" "-0.8277" "stackrel("(SHE)")(0.0000)" "" "1.34
<< --- | --- | --- | - >>

New Reduction Potential Scale (V)

" "" "" "0.0000" "stackrel("(SHE)")(0.8277)" "" "???
<< --- | --- | --- | - >>

Thus, color(blue)(E_"red,new"^@) = "1.34 V" + "0.8277 V" = color(blue)("2.17 V")

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