Single Replacement Reaction

The single replacement reaction in this lab is CuSO_4(aq) + Zn_(s) --> ZnSO_4(aq) + Cu_(s). The driving force for this reaction is formation of a solid (Cu), and this happens because zinc has the higher electronegativity and therefore pulls the sulfate ions away from the copper, leaving the copper all by itself plus Zinc Sulfate floating around in the solution.