Redox reactions and potentials/potential differences

  • Thread starter s3a
  • Start date
  • #1
s3a
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Hello to everyone who reads this. :)

Homework Statement


I DO understand the two following points.:

1. If the redox potential of a redox reaction is positive, then the redox reaction is spontaneous.

2. If the redox potential of a redox reaction is negative, then the redox reaction is NOT spontaneous/non-spontaneous.

What I am NOT 100 percent sure I understand is what a redox potential of 0 (so neither positive nor negative) means (since most, if not all, sources don't seem to mention that). I've been told that it means that the system is at equilibrium, which does make sense to me, but being told that, I have another (sub)question to inquire about this further. (See part 3, below.)

Homework Equations


http://chem.libretexts.org/Core/Phy...es_of_Chemical_Equilibria/Dynamic_equilibrium

The Attempt at a Solution


Basically, a redox reaction with a potential of 0 means the system in question is ALWAYS in DYNAMIC equilibrium (and never static equilibrium), since redox reactions ALWAYS have motion between reactants and products, albeit at an equal and constant rate, when the redox potential of a redox reaction is 0, right?

If I'm wrong, please correct me.

Any input would be GREATLY appreciated!

P.S.
"Potentials" = "Potential differences", right?
 

Answers and Replies

  • #2
Borek
Mentor
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I DO understand the two following points.:

1. If the redox potential of a redox reaction is positive, then the redox reaction is spontaneous.

2. If the redox potential of a redox reaction is negative, then the redox reaction is NOT spontaneous/non-spontaneous.

I am not sure I understand what it is supposed to mean.

What do you mean by "redox reaction"? The one in which two half cells are combined to react?

If so, whether the cell potential is positive or negative is just a matter of how the half cells are connected to the voltmeter and the negative potential can be made positive just by switching the cells. But you can't make the system spontaneous just by shifting flasks, so there is something wrong.

And if by "redox reaction" you mean a half cell reaction, it is never spontaneous, as it won't work without an electron source (or sink) which is typically a second half cell. Which moves us back to the first case (which is already wrong).
 

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