Question

Question #cde21

Answer 1

It's arbitrary. We could have set it to be `"1.752452352 V"`, but we felt like `"0.000 V"` was a nicer number. I'm not kidding.

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There are other reference electrodes, a common one being the saturated calomel electrode (SCE):

`"Hg"_2^(2+)(aq) + 2e^(-) rightleftharpoons 2"Hg"(l)`

In reference to that, all reduction potentials will differ; its reduction potential is `"0.2444 V"` relative to the standard hydrogen electrode (SHE).

If we use the SCE as a reference, we decrease numbers previously relative to the SHE by `"0.2444 V"`. For instance, a potential relative to SHE of `"1.7000 V"` would become `"1.4556 V"` when relative to the SCE.