1. The problem statement, all variables and given/known data What is the maximum [Ca2+] that can exist with 5.2e-4 M c2O4 2- without precipitating? Ksp for CaC2O4 = 2.6e-9. 2. Relevant equations Well, the Ksp and M is given, I don't know how to apply them. 3. The attempt at a solution I need help because I missed the lesson. Thank you.