R and Nernst equation

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Jorja De Jesus 2C
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Joined: Sat Jul 20, 2019 12:15 am

R and Nernst equation

Postby Jorja De Jesus 2C » Sat Mar 14, 2020 8:14 pm

When using R (the 8.314 version) with the Nernst equation, what should the units be in the end and how do the units cancel out to that? Also could the other variations of R be used in the Nernst equation too?

Indy Bui 1l
Posts: 99
Joined: Sat Sep 07, 2019 12:19 am

Re: R and Nernst equation

Postby Indy Bui 1l » Sat Mar 14, 2020 8:17 pm

If you write out the units for all the constants in the equation you can see how they cancel out. I believe the final units should simplify out to V. I think you always use 8.314 for R because the J cancels out.

Posts: 108
Joined: Thu Jul 25, 2019 12:16 am

Re: R and Nernst equation

Postby JamieVu_2C » Sat Mar 14, 2020 8:20 pm

The Nernst equation is E = E(standard) - (RT/nF)lnQ. Since R = 8.314 J * K^-1 * mol^-1, it will cancel out with the units for T, temperature, at Kelvin. the mol in R will also cancel with the mol for Faraday's constant, which is C/mol. Then, what you end with for the units of (RT/nF) is J/C, which essentially equals a volt. Because lnQ has no units, you will end up with volts and E(standard) will also be in volts.

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