Chapter 19, Problem 4E

Ascorbic acid ( ${\text{C}}_{\text{6}}{\text{H}}_{\text{6}}{\text{C}}_{\text{6}}$ , also commonly known as vitamin C, can used to reduce a wide variety of transition metal ions. Given that $E_{col}=0.71\text{V}$ for the reaction ${\text{C}}_{\text{6}}{\text{H}}_{\text{6}}{\text{O}}_{\text{6}}\left(\text{aq}\right)+2{\text{Fe}}^{\text{2+}}\left(\text{aq}\right)\to {\text{C}}_{\text{6}}{\text{H}}_{\text{6}}{\text{O}}_{\text{6}}\left(\text{aq}\right)+2{\text{Fe}}^{\text{2+}}\left(\text{aq}\right)+2{\text{H}}^{+}\left(\text{aq}\right)$ , what is $E°$ for the half-cell reaction ${\text{C}}_{\text{6}}{\text{H}}_{\text{g}}{\text{O}}_{\text{g}}\left(\text{aq}\right){\text{+2H}}^4\left(\text{aq}\right)+2{\text{e}}^{\text{-}}\to {\text{C}}_{\text{6}}{\text{H}}_{\text{6}}{\text{O}}_{\text{6}}\left(\text{aq}\right)$ ?