Calculate Keq for 1 moles of electron(s) in each half-reaction and a standard potential of 0.38 V. A half-cell that consists of a copper wire in 1.00 M CuNO3 solution is connected by a salt bridge to a half cell containing a 1.00 M X(II) acetate solution and an electrode of metal X. The voltage of the cell is 2.21 V, with metal X as the positive electrode. The standard reduction potential of the copper half-reaction is 0.52 V.