Question

Can copper displace zinc from its salt solution?

\[\ce{E^{\circ}_{{Zn^{2+}/{Zn}}}}\] = −0.76 V, \[\ce{E^{\circ}_{{Cu^{2+}/{Cu}}}}\] = +0.34 V

Answer 1

Given: \[\ce{E^{\circ}_{{Zn^{2+}/{Zn}}}}\] = −0.76 V

\[\ce{E^{\circ}_{{Cu^{2+}/{Cu}}}}\] = +0.34 V

The reaction is:

\[\ce{Cu + Zn^2+ -> Cu^2+ + Zn}\]

This reaction would require Cu to be oxidised and Zn²⁺ to be reduced.

The standard electrode potential of a cell is:

\[\ce{E{^{\circ}_{cell}} = E{^{\circ}_{cathode}} - E{^{\circ}_{anode}}}\]

= −0.76 − 0.34

= −1 V

Since E°cell is negative, the reaction is not spontaneous. So, copper cannot displace zinc from its salt solution.