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Cell Concentration

Posted: Tue Mar 13, 2018 11:57 pm
by Abigail Volk 1F
On one of the bullet points on the electrochemistry outline says "understand how a concentration cell works and give an example." What is an example of cell concentration, or what is Lavelle looking for when answering this?

Re: Cell Concentration

Posted: Wed Mar 14, 2018 8:07 am
by Ryan Sydney Beyer 2B
I think Dr. Lavelle is talking about a cell that runs on the concentration difference between two chambers of the cell. He went over examples of these during lecture - different from a galvanic cell b/c doesn't depend on the oxidizing power / reducing power but instead on the conc. difference between two species.

Re: Cell Concentration

Posted: Wed Mar 14, 2018 9:04 am
by Samantha Joseph 1F
I think you just have to understand it conceptually, like how a concentration cell can be treated like a battery that gains voltage by transferring electrons from the lower concentrated cell to the higher concentrated cell. I think it's also supposed to be an example for application of the Nernst equation.

Re: Cell Concentration

Posted: Fri Mar 16, 2018 6:53 pm
by Rachel Wang
A concentration cell has the same electrode/element for both half cells BUT with different concentrations.

All concentration cells have E(nought) = 0.

Use the Nernst equation
E = Eo - 0.05916 V/n x log Q
or
E = 0 - 0.05916 V/n x log Q. You get Q from the overall redox rxn, which usually has the smaller Molarity on the product side.