Question

Calculate the standard EMF of a cell which invovles the following cell reaction `Zn+2Ag^(+)toZn^(2+)+2Ag`
Given that `E_(Zn,Zn^(2+))^(@)=0.76 "volt" and E_(Ag,Ag^(+))^(@)=0.080` volt.

Answer 1

The cell reaction may be split into two half reactioin as:
`ZntoZn^(2+)+2e^(-)` (oxidation half reaction)
`2Ag^(+)+2e^(-)to2Ag` (Reduction half reaction)
Here, we are given standard oxidation potentials as `E_(Zn,Zn^(2+))^(@)=0.76` volt and `E_(Ag,Ag^(+))^(@)=0.80` volt
We need oxidation potential of zinc electrode but reduction potential of silver electrode.
Reduction potential of Ag electrode=-Oxidation potentil of Ag electrode
=-(-0.80 volt)=+0.80 volt
Std. EMF of the cell=Std. oxid. potential of zinc electrode+Std. redn. potential of Ag electrode
=+0.76+0.80 volt=1.56 volts.