Given,`{:(E_(Fe^(3+) //Fe)^o + 3e Cr E^o =- 0.036 V),(E_(Fe^(3+) //Fe)^o =- 0.439 V):}`
The value of standard electrode ptoential for the charge,

Options

A. `0.072V`
B. 0.3850V
C. 0.770V
D. 0.270V

Answer

C

Explanation

`Fe^(3+)+3e^(-)rarrFe,E_(1)^(@)=- 0.036V`
`Fe^(2+)+2e^(-)rarrFe,E_(2)^(@)=- 0.439V`
`therefore` Now `Fe^(3+)+e^(-)rarrFe^(2+),E_(3)^(@)=`?
Now `DeltaG_(3)=DeltaG_(1)-DeltaG_(2)`
`therefore DeltaG_(2)=3xx0.036F-2xx0.439F`
`therefore DeltaG_(3)=0.108F-0.878F`
`therefore -1xxFxxE_(3)^(@)=-0.770F`
`E_(3)^(@)=0.770V`