sudo

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Sep 12, 2011
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First off, do we know that a redox reaction will take place because we're working with a Galvanic Cell? If the cell was electrolytic instead of galvanic, would the reaction still occur spontaneously?

Secondly, what made the potential of the first half-reaction turn positive? And how did we know to add those two potentials, instead of subtracting them?



I hope I made sense - redox has always confused me...
 

MedPR

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Galvanic = spontaneous.
Electrolytic = requires voltage source (not spontaneous).

Galvanic cells will always have a positive potential. There are several ways to calculate the overall potential, and the easiest imo is to add the potential of the reduction reaction to the oxidation reaction. If you do it this way you will most likely have one positive number and one negative number.

Other people convert both and subtract or add, depending on their conversion.
 
OP
sudo

sudo

Señor Member
7+ Year Member
Sep 12, 2011
431
33
Status
Medical Student
Galvanic = spontaneous.
Electrolytic = requires voltage source (not spontaneous).

Galvanic cells will always have a positive potential. There are several ways to calculate the overall potential, and the easiest imo is to add the potential of the reduction reaction to the oxidation reaction. If you do it this way you will most likely have one positive number and one negative number.

Other people convert both and subtract or add, depending on their conversion.
Makes sense for the most part - but I'm still a little confused by what you mean on the bolded part...

Thanks though :)