The precipitate is then filtered from the solution, dried, and weighed. When 20.0mL of a 0.250 (NH4)2S solution is added to a 150.0mL of a solution of Cu (NO3)2,a CuS precipitate forms. If the recovered CuS is found to have a mass of 0.3491 g, identify what was the concentration of copper ions in the original Cu (NO3)2 solution?