The standard electrode potential of `Cu,Cu^(2+)` is -0.34 volt. At what concentration of `Cu^(2+)` ions will this electrode potential be zero?

Explanation

For the electrode reaction (reduction)
`Cu^(2+)+2e leftrightarrow Cu, E^@=+0.34 vol t`
`E_(cu)^(2+)= E_(cu_(2+))^(@), Cu- 0.0591/2 log""1/([Cu^(2+)])`
`E^@ + 0.0591/2 log [Cu^(2+)]`
`therefore 0=0.34+0.0591/2 log [Cu^(2+)]`
or `log[Cu^(2+)]=-11.5059=overline12.4941`
Taking antilog
`[Cu^(2+)]=3.12 times 10^(-12) M`