Copper Electroplating, cell voltage = 0V?

[tinska.h]

Hello everybody,

this is probably a very novice question, but imagine anode and cathode, both made from copper immersed in CuSO4 aqueous solution (1M at standard temp and pressure + assuming electrodes are very near each other -> minimizing diffusion/migration resistance) and:

Cu(2+) + 2e- -> Cu(s) = 0.337V (SHE)
and
Cu(s) <- Cu(2+) + 2e- = -0.337V (SHE)

In this scenario would the cell voltage be 0V? In literature and articles Ecell is usually defined as Ecell = Eox + Ered.

If this is correct, does the CuSO4 molar concentration affect Ecell if electrodes are very near each other? How does one determine activity coefficient in Nernst equation?

Thanks!

 

[Borek]

Yes, E cell would be 0. Activity - as a first approximation - equals ion concentration. Google "concentration cell".

 

[tinska.h]

Thanks for the help.

In concentration cell, it would need to have concentration gradient. But what about in electroplating bath, where concentration is quite stable across the bath? How do I determine Ecell deviation from SHE for example in 0.1M CuSO4 or 5M CuSO4?

Also, since SHEs are performed on Platinum (or platinized?) electrode, are there analytical methods for determining overpotentials for various different electrode materials? Or are there good lists available? For example does oxygen evolution differ from SHE on copper electrodes?

Thanks!

 

[Borek]

In electroplating you force voltage upon the cell, so the voltage of the cell itself doesn't matter (much).