The standard half-cell reduction potential for `Ag'|Ag` is 0.7991 V at `25^(@)C`. Given the experimental value `K_(sp) =1.56xx10^(m)` for AgCl, calculate the standard half-cell reduction potential for the AglAgCI electrode.

Options

A. `0.2192 V `
B. ` - 0.2192V `
C. ` -1.2192 ` V
D. `1.2192 V `

Answer

A

Explanation

For the desired reaction `AgCl+1e^(-) to Ag+Cl^(-), E^(@)+=(-Delta_(r) G^(@))/((1)F))`
The needed `Delta_(r)G^(@)` can be obtained by adding the value of `Delta_(r)G^(@)` for the reactions
`Ag^(+)+1e^(-)l, DeltaG^(@)=nFE^(@)`
`AgCl to Ag^(+)+Cl^(-_),DeltaG^(@)=-RT ln K_(p)` giving `Delta_(r)G^(@)=-(1"mol")(298K)ln (1.56xx10^(-10))`
`=-77.10kJ+55.95kJ=-21.15kJ`
The potential is `E^(@)=(-(-21.15))/((1)(96.485))=+0.2192V`