In water softening treatments, magnesium ion can be precipitated as Mg(OH)2 by increasing the pH of the water. If the initial concentration of Mg2 is 8.5 × 10-4 M, at what pH will 50% of the Mg2 be removed by precipitation (Ksp Mg(OH)2 = 5.61 × 10-12)? At what pH will 90% of the Mg2 be removed by precipitation? Why is COz bubbled through water after such a precipitation?
