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bishtap

question about the definition of electrolysis in AP Chemistry

I notice that the specification says

"thermodynamically unfavored (ΔG° > 0)."

That's fine and correct.

And it says "electrolytic cells involve a thermodynamically unfavored reaction"

Isn't that a problematic statement.. Because for example, if we take an electroplating example, the ECell could be 0. And electroplating is meant to be an example of electrolysis.

e.g. If we have a beaker containing silver nitrate, a silver rod, a copper ring, and a battery used to silver plate the copper ring, then the redox reaction is the two half reactions

Ag^(+) + e^(-) => Ag (s) E(red)= 0.800

and

Ag (s) => Ag^(+) + e^(-) E(ox) = -0.800

So ECell = 0

If the statement in the curriculum had said that electrolytic cells involve a reaction that is not thermdynamically favoured, (aka not spontaneous), then that'd be correct.

Like Not positive, includes 0 and negative. Whereas the word "Negative", excludes 0. And they are meant to be including 0. Because electroplating including that example where Ecell=0, is considered to be electrolysis.

Any case of a battery driving a reaction that is not spontaneous i.e. driving a reaction that is not thermdynamically favoured.. counts as electrolysis.

It may be that some texts make that statement that electrolysis is where a non-spontaneous / thermodynamically unfavourable reaction is driven by a battery. But technically it seems to me it should say drives a not spontaneous reaction. Or for better flowing English, drives a reaction that is not spontaneous.

I saw an advanced book on electrochemistry.. by fuller and harb, that (rightly) says "If the reaction is spontaneous, then we can obtain work from the reaction. If it is not spontaneous as written, then we would need to add work to force the reaction to go in that direction."

We can change the word spontaneous to thermodynamically favoured and it means the same thing.

Wouldn't the curriculum be more correct if it said Electrolyic cells involve a reation that is not thermodynamically favoured.. Instead of what it currently says, which is "electrolytic cells involve a thermodynamically unfavored reaction" ?

AP might even use that silver nitrate, silver rod,copper ring example that has Ecell=0 . I've seen the example asked about here.

Posted May 12, 2026, 2:58 PM UTC

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