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### Final 2014 Question 4 (Pikachu Galvanic Cell)

Posted: Thu Mar 10, 2016 2:17 pm
Im confused on part A. For this question, how do we know which chemicals to choose? From what I remember, in order to get the highest possible voltage you would choose too reactions that have the biggest charge difference of Ecell in order to get the largest positive value of Ecell. I'm just not sure how they picked the chemicals that they did in this case.

### Re: Final 2014 Question 4 (Pikachu Galvanic Cell)

Posted: Thu Mar 10, 2016 4:06 pm
This is what was done. The explanation on the bottom of page 217 accounts for the choice of chemicals. Choosing half-reactions involving solid Cu or Fe will end up producing a lower final voltage than choosing solid Zn and the "all aqueous" Fe3+ + e- $\rightarrow$ Fe2+.