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Electrochemistry and concentration

1. a) A copper refining cell is operating with an electrolyte which contains 0.05 m Sn2+. At what concentration of Cu2+ will the tin start to plate out in preference to the copper? The cell temperature is 40°C.

b) A polarization potential arises from a concentration difference between ions in the neighborhood of the electrode and those in the bulk of the electrolyte solution. Calculate the polarization potential in a copper electrorefining cell given the following information:

Cell temperature: 40°C
Cu2+ concentration in the bulk of the solution: 1.0 m
Cu2+ concentration adjacent to the anode: 5.0 m
Cu2+ concentration adjacent to the cathode: 0.2 m

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Solution Preview

Please see the attachment.

G =-nRTlnK
G = -nEF
-nRTlnk = -nEF
RTlnK = EF
E = RTlnK
Cu ↔ Cu2+ +2e
K = [Cu2+][2e]
[Cu] and [2e] remain unchanged and assuming they have unity value.

E = ...

Solution Summary

The solution provides detailed equational explanation of how to determine concentration and polarization.