Question

How would you change ${\mathrm{Cu}}^{2+}$ ion to $\mathrm{Cu}$?

Answer 1

There is a change of ${\mathrm{Cu}}^{2+}$ ion to $\mathrm{Cu}$ by reacting copper (II) salt with a more reactive metal as in reactivity series in an aqueous solution.

When copper salt reacts with iron then copper is displaced by iron and forms the ${\mathrm{Cu}}^{2+}$ ion to $\mathrm{Cu}$

Reaction:

$$\begin{gathered} \mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\to {\mathrm{FeSO}}_4\left(\mathrm{aq}\right)+\mathrm{Cu}\left(\mathrm{s}\right) \\ (\mathrm{copper}\mathrm{sulphate})(\mathrm{iron}\mathrm{sulphate}) \end{gathered}$$