In my experiments I mixed different ratios of CuSO4 and NaS. The ratio in which I had the greatest amount of precipitate was when I mixed 3mL CuSO4 : 3mL NaS. Now my question: What is indicated by the maximum amount of precipitate...? Thanks in advance.

If the concn CuSO4 was the same as Na2S (note the typo), it shows Cu and S reacted 1:1