The overpotential is the difference between the actual potential applied and the standard potential for the reaction. In this case, the standard potential for the reduction of copper ions to copper metal is +0.34 V, and the actual potential applied is +0.50 V.Overpotential = Actual potential - Standard potentialOverpotential = +0.50 V - +0.34 V Overpotential = +0.16 VThe overpotential for the reduction of copper ions to copper metal at the cathode is +0.16 V.