Why doesn't a chemical reaction occur when you combine copper (II) sulfate and Aluminum??
A reaction occurs (but it is not a rapid reaction). A piece of Al will gradually display a Cu colored residue on its surface - that is metallic copper. 2Al + 3CuSO4 -- Al2(SO4)3 + 3Cu Al is higher on the activity series (it is more easily oxidized than Cu) so it will displace Cu from CuSO4.
Aluminum is less reactive compared to copper. Check out the reactivity series
Actually, aluminum is considerably more active than copper, but there is also usually a thin film of aluminum oxide on the metal surface that keeps it from reacting. If you added just a trace of acid to the system, copper would plate out on the exposed aluminum and the aluminum would go into solution in its place.
