Can a solution of 1M ZnSO₄ be stored in a vessel made of copper?
Given:
E°(Zn²⁺/Zn) = +0.76 V
E°(Cu²⁺/Cu) = +0.34 V

Since E°(Zn²⁺/Zn) = −E°(Zn/Zn²⁺) = 0.76 V is at a lower potential than E°(Cu²⁺/Cu) = 0.34 V, therefore Zn can only lose electrons to Cu²⁺ ions. Conversely, Zn²⁺ cannot accept electrons from Cu and hence the following reaction will not occur:

Zn²⁺ + Cu ⟶ Zn + Cu²⁺

In other words, ZnSO₄ solution can be safely stored in a copper vessel.