Given `E_(Fe^(3+)//Fe)^(@)=-0.036V` and `E_(fe^(2+)//Fe)^(@)=-0.44V` . What is the value of `E_(Fe^(3+)//Fe^(2+))^(@)`

Options

A. `(-0.036- 0.439)V`
B. `(-0.036+ 0.439)V`
C. `[3(-0.036+2(-0.439)]V`
D. `[3(-0.036-2(-0.439)]V`

Answer

D

Explanation

`{:(Fe^(3+) + 3e^(-) rarr Fe,Delta G_(1)^(@)= -(3)F(-0.036V)),(ul(Fe^(2+) + 2e^(-) rarr Fe),ul(Delta G_(2)^(@)= -(2)F (-0.439V))),(Fe^(3+) + e^(-) rarr Fe^(2+),Delta G= Delta G_(1)^(@)- Delta G_(2)^(@)= -F[3 (""^(-)0.036)- 2(""^(-)0.439)]V):}`
`E^(@)= [3 (""^(-)0.036)-2 (""^(-)0.439)]V (because Delta G= -nFE)`