`Cu^(2+)(aq.)` is unstable in solution and under goes simultaneous oxidation and reduction according to the reaction
`2Cu^(+)(aq.)hArr Cu^(2+)(aq.)+Cu(s)`
Choose the correct `E^(@)` for the above reaction if
`E_(Cu^(2+))^(@)//Cu = 0.34 V and E_(Cu^(2+))^(@)//Cu^(+) = 0.15 V`

Options

A. `-0.38V`
B. `+0.49V`
C. `+0.38V`
D. `-0.19V`

Answer

C

Explanation

From given data (From `Delta G^(@)=-NE^(@)F)`
`CU(s) to Cu^(2+)(aQ)+2e^(-)*DeltaG_(1)^(@)=-2xx(-0.34)xxF`
`(ii) Cu^(2+)(aq)e^(-) to Cu^(+)(aq).*DeltaG_(2)^(@)=-1xx(0.15)F`
On addition
`Cu(s) to Cu^(+)(aq)+e^(-). Delta G_(3)^(@)=-1xxE^(@)xxE`
`DeltaG_(3)^(@)= Delta_(2)^(@)`
`=(-2xx-0.34xxF)+(-1xx0.15xxF)`
`=+0.68F-0.16F=0.53F`
or `E^(@)=-0.53V`
Reaction,
`2Cu^(+)(aq) hArr Cu^(2)(aq)+Cu(s)E^(@)=?`
so, `Cu^(+)(aq)+e^(-) hArr Cu(s), E^(@)=+0.53V`
`Cy^(+)(aq) hArr Cu^(2+)(aq)+e^(-), E^(@)=-0.15V`
`2Cu^(+)(aq) hArr Cu^(2+)(aq)+Cu(s),E^(@)=+0.38V`