Question

The electrode potentials for \[\ce{Cu{^{2+}_{(aq)}} + e- -> Cu{^+_{(aq)}}}\] and \[\ce{Cu{^{+}_{(aq)}} + e- -> Cu_{(s)}}\] are +0.15 V and +0.50 V respectively. The value of  \[\ce{E^{\circ}_{{Cu^{2+}/{Cu}}}}\] will be:

Options

• 0.325 V

• 0.650 V

• 0.150 V

• 0.500 V

Answer 1

0.325 V

Explanation:

To find the overall standard electrode potential for:

\[\ce{Cu^2+ + 2e- −> Cu}\]

we combine the two half-reactions:

\[\ce{Cu^2+ + e- −> Cu+}\]; \[\ce{E^{\circ}_{1}}\] = +0.15 V

\[\ce{Cu+ + e- −> Cu}\]; \[\ce{E^{\circ}_{2}}\] = +0.50 V

Use the formula for combining two sequential redox steps:

\[\ce{E^{\circ}_{overall} = \frac{E^{\circ}_{1} + E^{\circ}_2}{2}}\]

= \[\ce{\frac{0.15 + 0.50}{2}}\]

= 0.325 V