Question

If `E_(Fe^(2+))^(@)//Fe = -0.441 V`
and `E_(Fe^(3+))^(@)//Fe^(2+) = -0.771 V`
The standard `EMF` of the reaction
`Fe+2Fe^(3+) rarr 3Fe^(2+)`
will be:
A. `0.111 V`
B. `0.330 V`
C. `1.653 V`
D. `1.212 V`

Answer 1

Correct Answer - D
Since no `e^(-)` is seen in the given reaction, it can be regarded as a cell reaction, whose standard EMF will be given as follows :
`E_("cell")^(@) = E_(R)^(@)-E_(L)^(@)`
Electrode having the higher reduction potential acts as cathode. Thus, `E_("cell")^(@) = (0.771 V)-(-0.441 V)`
`= 1.212 V`