Question

Can we store copper sulphate solution in zinc vessel? Give suitable explanation. 

Given: \[\ce{E_{Cu^{2+}/Cu}}\] = +0.34 V, \[\ce{E_{Zn^{2+}/Zn}}\] = −0.76 V, \[\ce{E_{Ag^{+}/Ag}}\] = +0.80 V

Answer 1

Copper sulphate solution cannot be stored in a zinc vessel because zinc is more reactive than copper. This is evident from the electrochemical series, where zinc has a much lower standard reduction potential (\[\ce{E_{Zn^{2+}/Zn}}\] = −0.76 V) compared to copper (\[\ce{E_{Cu^{2+}/Cu}}\] = +0.34 V). Since zinc is above copper in the series, it can readily displace copper from its salt solution.

The cell potential for the reaction:

\[\ce{Zn_{(s)} + Cu{^{2+}_{(aq)}} -> Zn{^{2+}_{(aq)}} + Cu_{(s)}}\]

is:

\[\ce{E^\circ_{cell} = E^\circ_{\ce{Cu^{2+}/Cu}} - E^\circ_{\ce{Zn^{2+}/Zn}}}\] = 0.34 − (−0.76) = +1.10 V

Since the value is positive, the reaction is spontaneous. Therefore, zinc dissolves in the solution, and copper is deposited, corroding the vessel.

Hence, copper sulphate solution cannot be stored in a zinc vessel.