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In the 7th edition of the textbook, the equation is explained on pg. 547. Basically, the change in Gibbs free energy equals the max nonexpansion work of an isobaric and isothermal reaction (). Work is done when electrons move through a potential difference, which it can be calculated by multiplying their total charge with the potential difference. So you need n, the number of electrons in moles, to calculate
n is the moles of electrons, just be sure not to confuse it with the moles of the agents. you can figure out the number of moles of electrons by writing both the half reactions and seeing the number of electrons transferred.
You need the moles of electrons transferred in a cell in order to cancel out the moles in Faraday's constant (mol x C/mol = C). To find the moles of electrons transferred, you write out both the oxidation and reduction half reactions, balance the reactions so the electrons cancel on both sides, and the coefficient of the electron in the balanced half reactions is your value for n. Review example 6L.1 and 6L.1A on page 685 in the 7th edition textbook for practice.
You need the moles of electrons transferred in a cell in order to make sure the units cancel out and you get your final answer in the correct units.To find n write out the half reactions to determine the amount of electrons are being transferred. Make sure not to add the electrons from both sides. If one one side you have -2e and the other you have -3e you find the lowest number that would cancel out electrons on both sides. For this example the number would be 6.
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