The Pb²⁺ ion buffer used inside the electrode for the colored curve in Figure 14-27 was prepared by mixing 1.0 mL of 0.10 M Pb(NO₃)₂ with 100.0 mL of 0.050 M Na₂EDTA. At the measured pH of 4.34,α γ₄- = 1.46 × 10^-8 (Equation 11-4). Show that [Pb²⁺] = 1.4 × 10^-12 M.

Figure 14-27

Equation 11-4

150 100 Conventional 50 filling solution -50 10-12 M Pb2 filling solution -100 -150 -12 -10 -8 -6 -4 -2 log[Pb?"] (Aw) 3