What is the solubility of erbium(Il) iodate in grams per 100 ml of water? What is the molar solubility of erbium) iodate in a solution that is 0.010 M in KIO (ag)? Solution Ksp of Er(IO 3 ) 3 = 2 x 10^-21 Er(IO3)3 ---------------> Er+3  +   3 IO3- S             3S Ksp = [Er+3] [IO3-]^3 2 x 10^-21 = S x (3S)^3 S = 2.93 x 10^-6 M solubility = 2.03 x 10^-3 g / L = 2.03 x 10^-3 g / 0.1 solubility   = 2.03 x 10^-4 g / 100 mL 2) Er(IO3)3 ---------------> Er+3  +   3 IO3- S            0.010 M Ksp = [Er+3] [IO3-]^3 2 x 10^-21 = S x (0.010)^3 S= 2 x 10^-15 M molar solubility = 2 x 10^-15 M .