Question

The standard oxidation potential `E^(@)` for the half cell reactions are
`Zn rarrZn^(2+)+2e^(-):E^(@)=+0.76V`
`FerarrFe^(2+)+2e^(-)"E^(@)=+0.41V`
EMF of the cell reaction
`Fe^(2+)+ZnrarrZn^(2+)+Fe` will be
A. ` -0.35V`
B. `+0.35V`
C. `+1.17V`
D. `0.117V`.

Answer 1

Correct Answer - B
`E_( Zn^(2+)//Zn)^(@)=-0.76V`
` E_(Fe^(2+)//Fe)^(@)=-0.41V`
`Fe^(2+)+ZnrarrZn^(2+)+Fe`
The two half cell reactions are
`Z nrarrZn^(2+)+2e^(-)`
`Fe^(2+)+2e^(-)rarrFe`
`therefore` Electrochemical cell is
`Zn||Zn^(2+)||Fe^(2+)|Fe`
`E_("cell")^(@)=E_(Fe^(2+)//Fe)^(@)- E_(Zn)^(@)2+_(//Zn)`
`=-0.41V-(-0.76V)=+0.35V`