Question

$C{u}^{+}$ is not stable and undergoes disproportionation. $E^o$ for $C{u}^{+}$ disproportionation is : $(E_{C{u}^{2+}/C{u}^{+}}^o=+0.153V,E{{}^o}_{C{u}^{+}/Cu}=0.53V)$

• A. +0.683 V
• B. -0.367 V
• C. +0.3415 V
• D. +0.377 V

Answer 1

Answer: (C)

+0.3415 V

The relationship between standard gibbs energy change for a reaction and its cell potential is ${\Delta G}^o=-nF{E}_{cell}^o$.

For copper electrodes,

${\Delta G}_{C{u}^{2+}|Cu}^o={\Delta G}_{C{u}^{2+}|C{u}^{+}}^o+{\Delta G}_{C{u}^{+}|Cu}^o$

$-nF{E}_{C{u}^{2+}|Cu}^o=-nF{E}_{C{u}^{2+}|C{u}^{+}}^o-nF{E}_{C{u}^{+}|Cu}^o$

$2\times E_{C{u}^{2+}|Cu}^o=1\times E_{C{u}^{2+}|C{u}^{+}}^o+1\times E_{C{u}^{+}|Cu}^o$

Substitute values in the above equation.

$2\times E_{C{u}^{2+}|Cu}^o=1\times E_{C{u}^{2+}|C{u}^{+}}^o+1\times E_{C{u}^{+}|Cu}^o$

$=0.153V+0.53V$

$E_{C{u}^{2+}|Cu}=0.3415V$

Option C is correct.