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Topic: electrolytic cell  (Read 3570 times)

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briteyellowness

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electrolytic cell
« on: August 16, 2005, 11:31:07 PM »
in an electrolytic cell in standard conditions, do you want E to be as negative as possible?

the question talks about plating copper onto a zinc coin.   the copper electrode and zinc coin are both stuck in a solution of CuSO4, and it said that Cu2+ has a more positive reduction potential than does Zn2+.  but if it's more positive, then it's more spontaneous, and in an electrolytic cell, it's a nonspontaneous process.  so why would i want a more positive reduction potential?

Offline mike

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Re:electrolytic cell
« Reply #1 on: September 12, 2005, 11:06:41 PM »
I am not entirely sure what the question is asking, however if you put a zinc coin into a solution of copper sulphate the copper will spontaneously deposit onto the surface of the coin. I am not sure why you would need a copper electrode as well.

You could use an electrolytic cell to reverse the process, for example you could plate a copper coin with zinc in a solution of zinc sulphate by applying a potential, in which case you would need a second electrode.
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Offline xiankai

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Re:electrolytic cell
« Reply #2 on: September 13, 2005, 12:42:29 AM »
the more positive the value of E, the easier it is for the half-reaction to be in the direction of one that gains electrons.

so Cu2+ is easier to reduce to a metal, while Zn2+ is harder.
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