The standard reduction potential of Cu^(2+)|Cu and Ag^+|Ag electrodes are 0.337 and 0.799 volt respectively. Construct a galvanic cellusing these electrodes so that its standard emf is positive. For what concentration of Ag^(+) will the emf of the cell at 25^@ C be zero if the concentration of Cu^(2+) is 0.01M?

The standard reduction potential of Cu^(2+)|Cu and Ag^+|Ag electrodes

1.	The standard reduction potential of Cu^(2+)\|Cu and Ag^+\|Ag electrodes are 0.337 and 0.799 volt respectively. Construct a galvanic cellusing these electrodes so that its standard emf is positive. For what concentration of Ag^(+) will the emf of the cell at 25^@ C be zero if the concentration of Cu^(2+) is 0.01M?
Answer» Solution :As `E_(AG^+)^@, Ag` is more POSITIVE than `E_(cu^(2+))^@, Cu` the FORMER will acts as cathode and the LATTER, anode. Thus the cell may be represented as `Cu,Cu^(2+)\|\|Ag^+, Ag` Further, given that `[Cu^(2+)]=0.01M and E_(cell)=0` we have, `E_(cell)=E_(Ag)^+, Ag-E_(cu)^(2+), Cu=0` `{ E_(Ag^+)^@, Ag+ 0.0591/1 log[Ag^+]}- {E_(cu^(2+))^@, Cu+ 0.0591/2 log[Cu^(2+)]}=0` or `{0.799+ 0.0591/2 log[Ag^+]}- {0.337+ 0.0591/2 log (0.01)}=0` or `log[Ag^+]=-8.8172=overline9 .1828` Taking antilog `[Ag^+]=1.52 times 10^-9 M`