Finding Standard Potential Through Compiling Half-Reactions


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Emilie Hoffman 1E
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Joined: Fri Sep 29, 2017 7:04 am

Finding Standard Potential Through Compiling Half-Reactions

Postby Emilie Hoffman 1E » Sat Feb 24, 2018 4:09 pm

Why can you assume that the deltaG of the final reaction is a composite of the deltaGs of the two other half reactions?

Nhan Nguyen 2F
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Re: Finding Standard Potential Through Compiling Half-Reactions

Postby Nhan Nguyen 2F » Sat Feb 24, 2018 4:15 pm

Gibbs free energy is a state function, which means that it takes in account of only the initial and final states of the system. Because it's a state function, we can assume that deltaGs of 2 half reactions can be added together to form the deltaG of the final reaction.

Rachel Formaker 1E
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Re: Finding Standard Potential Through Compiling Half-Reactions

Postby Rachel Formaker 1E » Sun Feb 25, 2018 12:06 pm

Even though ΔG of a final reaction will be the sum of the ΔGs of its composite reactions, it is important to note that this is not true of standard potential, Eo.
Since Eo is not a state function, you must manipulate the equations to use ΔG, which is a state function.

If reaction 1 + reaction 1 = reaction 3,

Then,
ΔG3 = ΔG1 + ΔG2

and since ΔG = -nFEo,
-n3FEo3 = -n1FEo1 + (-n2FEo2)


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