Consider the systems having liquid-solid interface, (a) copper wire in silver nitrate solution and (b) silver wire in copper sulphate solution.
Predict which interface will show spontaneous reaction, if
`E_(Cu^(2+)//Cu)^(@)=0.34V` and `E_(Ag^(+)//Ag)^(@)= 0.80V` ?

Options

A. Copper-silver nitrate interface
B. Silver-copper sulphate interface
C. There will be no spontaneous reaction
D. Both interfaces will give spontaneous reaction

Answer

A

Explanation

Spontaneous reaction can be determined on the basis of Gibbs free energy.
`DeltaG^(@)=-n FE^(@)`
`E^(@)=E_(c)^(@)-E_(A)^(@)`
`E_(c)^(@)` or `E_(Ag^(+)//Ag)^(@)=0.80V`
`E_(A)^(@)` or `E_(Cu^(2+)//Cu)^(@)=0.34V`
`E^(@)=0.80-0.34=0.34V`
`Delta G^(@)=-nFE^(@)=-2xx96500xx0.46V`
Hence, `Cu-Ag` nitrate interface show spontaneous reaction due to -ve value of `DeltaG^(@)`.