`E^(@)` values for `Fe^(3+)//Fe^(2+)` and `Ag^(+)//Ag` are 0.771 V and 0.8 respectively. Is the reaction,
`Fe^(3+)+Ag to Fe^(2+)+Ag^(+)`
Spontaneous or not ? Give reason also.

Explanation

Cell reaction is,
`Fe^(3+)+Ag to Fe^(2+)+Ag^(+)`
Half cell reaction are,
Oxidation: `Ag(s) to Ag^(+)(aq)+e^(-)`
Reduction: `Fe^(3+)(aq) +e^(-) to Fe^(2+)(aq)`
Overall: `Ag(s)+Fe^(3+)(aq) to Ag^(+)(aq)Fe^(2+)(aq)`,
`therefore` Cell can be represented as
`Ag|Ag^(+)||Fe^(3+),Fe^(2+)|Pt`
`EMF^(@)=E^(@)Fe^(3+)//Fe^(2+)-E^(@)Ag^(+)//Ag`
`=0*771V-0*800=-0*029V`
As `EMF^(@)` 0, the cell reaction in the given direction is non-spontaneous.