Mixing sodium sulfide (Na2S) with copper sulfate (CuSO4) in aqueous solutions will indeed result in the formation of a precipitate. The reaction between these two compounds can be represented as follows:

Na2S (aq) + CuSO4 (aq) → CuS (s) + Na2SO4 (aq)

In this reaction, the sodium and sulfate ions from sodium sulfide and copper sulfate, respectively, remain in the solution as spectator ions. The main reaction involves the formation of copper sulfide (CuS), which is an insoluble compound and, therefore, precipitates out of the solution.

Copper sulfide is a black solid, and its formation can be observed as a visible change in the reaction mixture. The precipitate typically settles at the bottom of the container or forms a suspension within the solution.

This reaction is commonly used to demonstrate precipitation reactions in chemistry education and as a method for removing copper ions from aqueous solutions, such as in wastewater treatment processes.