Standard Reduction Potentials

Many chemists use standard reduction potentials (SRP) instead of standard oxidation potentials (SOP). An example of this is shown in example 17 in your workbook (and on the SRP List page in the section). An abbreviated version is shown below for our immediate use. If you compare these two lists with one another, you will find that they are simply the reverse of one another in every way. Consequently, you need only one of these charts.

For example, if you look at the first reaction on the standard oxidation potential list, you can see that it's the reverse of the last reaction on the reduction potential list and the voltage is just the opposite. That is, if K becomes K⁺ and gives off one electron and has a voltage of 2.93 volts, then K⁺ taking on one electron to become K has a voltage of -2.93 volts.

Here is one more example. The S.O.P. list shows that lead becoming Pb²⁺ has a voltage of 0.13 volts. If, for some reason, you wanted to know about the tendency of lead ion to gain two electrons, you could simply find lead ion on the right side of the oxidation potential list and note that for it to gain two electrons, it must reverse the reaction as it is written and thus the voltage would be -0.13 volts.

One reason for giving you both the oxidation and the reduction potential list is so that you are aware of the similarity between the two and that you'd be able to use either of these lists, depending on what is available to you when you have to do a calculation or make a comparison.

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