Chapter 14, Problem 14.20QAP

Given the Information that

   $\begin{array}{l}{\text{Fe}}^{3+}+{\text{Y}}^{4-}\rightleftharpoons F\text{e}{Y}^{-}{\text{ K}}_i=1.0\times {10}^{25}\\ {\text{Cu}}^{2+}+{\text{Y}}^{4-}\rightleftharpoons C\text{u}{Y}^{2-}{\text{ K}}_i=6.3\times {10}^{18}\end{array}$

and the further information that, among the several reactants and products, only CuY^2- absorbs radiationat 750 nm, describe how Cu(II) could be used as an indicator for the photometric titration of Fe(III) with H₂Y^2-. Reaction:+ Fe³⁺+ H₂Y^2-→ FeY- + 2H⁺.