A concentration cell is constructed with two copper electrodes. The cathode is immersed in 0.500 M Cu(NO3)2 solution, while the anode is placed in an unknown Cu(NO3)2 solution of lower concentration. The temperature is maintained at 298 K, and the measured cell potential is 0.0395 V.
The standard reduction potential for Cu2+ + 2 e− → Cu(s) at 25 °C is +0.34 V.
(a) Write the balanced overall reaction for the concentration cell, indicating which side of the cell gains mass and which loses mass.
(b) Determine the number of electrons transferred per mole of overall reaction.
(c) Calculate the molar concentration of Cu2+ in the anode compartment that corresponds to the observed cell potential.
(d) If 0.250 g of copper metal plates onto the cathode while the cell operates at constant potential until equilibrium is reached, estimate whether the final cell potential is expected to be greater than, less than, or equal to 0.0395 V. Provide a qualitative justification based on the change in concentrations.