A half-cell that consists of a copper wire in a 1.00 M Cu(NO₃)₂ solution is connected by a salt bridge to a solution that is 1.00 M in both Pu³⁺ and Pu⁴⁺, and contains an inert metal electrode. Th e voltage of the cell is 0.642 V,

with the copper as the negative electrode.

(a) Write the half-reactions and the overall equation for the spontaneous chemical reaction.

(b) Use the standard potential of the copper half-reaction,

with the voltage of the cell, to calculate the standard reduction potential for the plutonium half-reaction.