1. The problem statement, all variables and given/known data 1. A 1L solution contains 0.1M of each Pb+2,Ca+2, and Sr+2. Which ion precipitates last as Na2SO4 is slowly added with no change in volume? 2. What is the concentration of the ion that precipitates first when the second ion precipitates? Given: Ksp PbSO4=1.8x10^-8 Ksp CaSO4=7.1x10^-5 Ksp SrSO4=3.4x10^-7 2. Relevant equations 3. The attempt at a solution 1. Pb2+ precipitates first as it has the lowest Ksp value. 2. This is where i get stuck. I know SrSO4 is the second ion to precipitate. I get: ksp=[Sr2+][SO42-] 4x10^-7=[Sr2+][SO42-] Don't know where to go from here. Help is appreciated.