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 Charge? Current?! Examples
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The word "spontaneous" keeps cropping up in one form or another. By now you should know what's coming! Electrochemical cells provide some of the most concrete examples of how chemical reactions can do work (or have work done on them). It should not be surprising that the magnitude and sign of the standard voltage, Eo, is in some way related to the standard free energy change, ΔGo. The mathematical relationship looks like this:where n is the number of moles of electrons transferred in the
cell reaction and F is a constant known as the Faraday (after British
scientist Michael Faraday). The value of the Faraday is 96,500
Coulombs/mol e-. A Coulomb is a unit of electric
charge (named for a French physicist). It is equivalent to a
current of 1 Ampere (you guess...) flowing for a period of 1
second. |
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The standard free energy calculated from this expression
will have units of J/mol.