At equimolar concentrations of Fe^(2+) and Fe^(3+), what must [Ag^(+)] be so that voltage of the galvanic cell made from Ag^(+)//Ag and Fe^(3+)//Fe^(2+) electrodes equals zero ? The reaction is Fe^(2+)+Ag^(+) hArr Fe^(3+)+Ag. Determine the equilibrium constant at 25^(@)C for the reaction. ("Given: "E_(Ag^(+)//Ag)^(@)=0.799" volt and "E_(Fe^(3+)//Fe^(2+))^(@)=0.771" volt")

At equimolar concentrations of Fe^(2+) and Fe^(3+), what must [Ag^(+)]

1.	At equimolar concentrations of Fe^(2+) and Fe^(3+), what must [Ag^(+)] be so that voltage of the galvanic cell made from Ag^(+)//Ag and Fe^(3+)//Fe^(2+) electrodes equals zero ? The reaction is Fe^(2+)+Ag^(+) hArr Fe^(3+)+Ag. Determine the equilibrium constant at 25^(@)C for the reaction. ("Given: "E_(Ag^(+)//Ag)^(@)=0.799" volt and "E_(Fe^(3+)//Fe^(2+))^(@)=0.771" volt")
Answer» Solution :`E_(cell)^(@)=E_(FE^(2+)//Fe^(3+))^(@)+E_(Ag^(+)//Ag)^(@)` `=-0.771+0.799=0.028` VOLT At equilibrium, `E_(cell)=0` `0=E_(cell)^(@)-0.0591/1 "log" ([Fe^(3+)])/([Fe^(2+)][Ag^(+)])` `=E_(cell)^(@)-0.0591"log"1/([Ag^(+)])` `[Ag^(+)]=0.34` `log K=(NE^(@))/(0.0591),""K=3.0`