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# Cell Potential and Reduction Potentials

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Hi. Can someone please explain to me how to do the following question? I'm quite confused about how to do these. See attachment for better notation representation.

Consider the following reaction at 25 degrees C, [Al3+] = 2.0 M and [Zn2+] = 1.0M

2 Al (s) + 3 Zn2+ (aq) -> 3 Zn (s) + 2 Al3+ (aq)

a) Predict if the cell potential, Ecell > Eocell or Ecell < Eocell. Explain why.
(I don't know how to determine this. Actually, I'm not even certain what the difference is between Ecell and Eocell. Please explain.)

b) Calculate Eocell given the half-reduction potentials.

Zn2+ (aq) + 2 e- -> Zn (s) Eo = -0.76 V
Al3+ (aq) + 3 e- -> Al (s) Eo = -1.66 V

I think the Eocell = +1.66 - 0.76 = +0.9 V
Is that right?

c) How many electrons are transferred in the reaction?

d) Calculate Ecell for the reaction using the Nernst equation.

I really don't know how to do this one. I know that the Nernst equation is
Ecell = Eocell (-RT/nF) ln Q, but I'm not sure what Q is or what Temp to apply here.

##### Solution Summary

This solution contains stepwise explanations that differentiates Ecell and Eocell, as well as calculates the Eocell for the half-reduction potentials and how many electrons are transferred in the reaction. In addition, the Nernst equation is explained and used to calculate Ecell.

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