Question

A Cu/Cu2+ concentration cell (E∘=0.34V) has a voltage of 0.23 V at 25 ∘C. The concentration of Cu2+ in the cathode is 1.6×10⁻³ molL−1.

Part A

What is the concentration of Cu2+ in anode?

Answer 1

Cu(s) ------------> Cu^+2 + 2e^- will occur in the less concentrated unknown cell

Cu^+2 + 2e^- -------> Cu(s) will occur in the 1.6*10^-3M solution

Thus the unknown cell will become more concentrated and the known cell will become less concentrated.
Cu(s) + Cu^+2 (1.6*10^-3 M)----------> Cu(s) + Cu^+2 (?)
E   = E0 -0.0592/n logQ

0.23   = 0-0.0592/2 log[Cu^+2]/1.6*10^-3
0.23 = -0.0296log[Cu^+2]/1.6*10^-3
-7.77   = log[Cu^+2]/1.6*10^-3
[Cu^+2]/1.6*10^-3   = 10^-7.77

[Cu^+2]/1.6*10^-3   = 1.7*10^-8

[Cu^+2]                  = 2.72*10^-11 M