At equimolar concentration of `Fe^(+2)//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

3

Explanation

`E_(cell)^(@) = E_(Fe^(2+)//Fe^(3+))^(@) +E_(Ag^(+)//Ag)^(@) =`
`- 0.771 +7999 = 0.028` volt,
Atequilibrium
`E_(cell) = 0 0 = E_(cell)^(@) - (0.0591)/(1)log. ([Fe^(3+)])/([Fe^(2+)][Ag^(+)])`
`E_(cell)^(@) - 0.5911 log. (1)/([Ag+])`
`[Ag^(+)] = 0.34, log K = (nE^(@))/(0.0591) K = 3.0`