Concentration effect on E

[Ryan Yoon 1L]

Why is that if you increase the concentration of product, E is smaller than E standard?

[Rita Chen 1B]

I think it depends on the reaction? I could be wrong, but in Dr. Lavelle's example today, the increasing in Mn concentration, caused the forward reaction to be favored, making E increase since the E standard was positive. I think it depends what you increase in concentration.

[Alice Chang 2H]

I think it's similar to the concepts of Le Chatelier's Principles.

This website talks a bit about it with a worked example: https://www.mikeblaber.org/oldwine/chm1046/notes/Electro/Conc/Conc.htm

[PranaviKolla2B]

Could someone explain what exactly E is?

[Emily Chirila 2E]

If you increase the concentration of the product > 1.0M, we get a larger value of Q (CONCENTRATIONproducts/CONTENTRATIONreactants) which is used in the equation:

E= E(standard conditions) - (RT/nF(lnQ))

Taking the ln of a Q that is more than 1 gives a positive number for lnQ, which is being subtracted from E(standard conditions), thus giving a smaller Ecell value in comparison to E(standard conditions)

If you were increasing concentration of reactants > 1.0M, you would end up with a Q that is less than 1, resulting in a negative value for lnQ. This changes the subtraction to addition and you end up getting a value for Ecell that is larger than E(standard conditions)