Chapter 18, Problem 18.101QE

At 298 K, the solubility product constant for PbC₂O₄ is 8.5 × 10⁻¹⁰, and the standard reduction potential of the Pb²⁺(aq) to Pb(s) is −0.126 V.

1. (a) Find the standard potential of the half-reaction

${\text{PbC}}_2{\text{O}}_4(\text{s})+2{\text{e}}^{-}\to \text{Pb}(\text{s})+{\text{C}}_2{\text{O}}_4^{2-}(\text{aq})$

(Hint: The desired half-reaction is the sum of the equations for the solubility product and the reduction of Pb²⁺. Find ΔG° for these two reactions and add them to find ΔG° for their sum. Convert the ΔG° to the potential of the desired half-reaction.)

1. (b) Calculate the potential of the Pb/PbC₂O₄ electrode in a 0.025 M solution of Na₂C₂O₄.