At equimolar concentration of `Fe^(2+)` and `Fe^(3+)`, what must `[Ag^(+)]` be so that the voltage of the galvanic cell made from the `(Ag^(+) | Ag)` and `(Fe^(3+)|Fe^(2+)` electrodes equals zero?
`Fe^(2+) + Ag^(+) rightarrow Fe^(3+) + Ag`
`E_(Ag^(+), Ag)^(@)`= 0.7991, `E_(Fe^(3+)//Fe^(2+))^(@) = 0.771`

Options

A. 0.34
B. 0.44
C. 0.47
D. 0.61

Answer

A

Explanation

`0=(0.771+0.7991)-(0.0591)/(1)log((1)/(x))implies0=0.0281+0.051logX`
`logX=-(0.0281)/(0.0591)impliesX=0.335M`