Emf

[datdat]

in the reaction A+B --> c+D and the EMF = -2.85V

kbb p.960 says "reaction proceed spontaneously to the left"

how do we know the reaction direction out of EMF?

could anyone give me some explanation?

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[ResidentPersian]

It's first important to remember a few things: A reaction is spontaneous (in the forward direction) if K>1, delta G = - , and EMF = +.

Though I dont' remember encountering a problem like this in the past, I can deduct from the info I just wrote that since EMF = -, it cannot be spontaneous in the forward direction, so it must be spontaneous in the reverse. It's generally one or the other. Just manipulate the above info to come to ur answer.


Just my two cents.

 

[toothdoc0121]

G= -n*F*E

because in this problem emf is negative, it makes G positive and a rxn can only proceed in the forward direction if G is negative. Also because G is nonsponatnous in the forward direction, this would make the reverse process spontaneous.

hope this helps