The standard reduction for the following reactions are :
`Fe^(3+) + 3e^(-) rarr Fe` with `E^(@) = - 0.036 V`
`Fe^(2+) + 2e^(-) rarr Fe` with `E^(@) = - 0.44 V`
What would be the standard electrode potential for the reaction `Fe^(3+) + e^(-) rarr Fe^(2+)` ?

Options

A. 0.772 V
B. 0.077 V
C. `-0.404 V`
D. `0.772 V`

Answer

A

Explanation

`{:(Fe^(3+)+3e^(-) rarr Fe,E_(1)^(@)=-0.036 V" "(n_(1)=3)),(Fe" "rarr Fe^(2+)+2e^(-),E_(2)^(@)=+0.44 V" "(n_(2)=2)),(bar(Fe^(3+)+e^(-) rarr Fe^(2+)" "),E_(3)^(@)=?" "(n_(3)=1)):}`
`n_(3)E_(3)^(@)=n_(1)E_(1)^(@)+n_(2)E_(2)^(@)`
`1xxE_(3)^(@)=3(-0.036)+2(+0.44)`
`E_(3)^(@)=0.772 V`