Question

You want to store a freshly made solution of copper sulphate. You have 4 options with you. Which of these is preferable to ensure that the solution remains intact?

Reduction potentials:
$Z{n}^{2+}/Zn=-0.76$
$M{g}^{2+}/Mg=-2.37$
$C{u}^{2+}/Cu=0.34$
$A{g}^{+}/Ag=0.8$
$S{n}^{2+}/Sn=0.16$

• A. Zn vessel
• B. Magnesium vessel
• C. Tin vessel
• D. Silver vessel

Answer 1

The correct option is D Silver vessel

Don't you think that we need to choose a container which would not react with Copper Sulphate and displace Copper? In this case, we would not be spoiling the solution of Copper Sulphate.
So, we need to pick a metal which is lower down in the electrochemical series as compared to Copper. In other words, we need to pick the metal which has a higher reduction potential than that of Copper's. If you take a look at the series, you will find this -

$Z{n}^{2+}/Zn=-0.76$
$M{g}^{2+}/Mg=-2.37$
$C{u}^{2+}/Cu=0.34$
$A{g}^{+}/Ag=0.8$
$S{n}^{2+}/Sn=0.16$

From the options given, we would be choosing Silver since it would not displace Copper from its solution.
For the displacement reaction to happen, we will need to choose the metal of higher reduction potential.