Use the following data to calculate the K sp value for each solid. (a) The solubility of FeCO 3 is 5.6???10 ?4 g/L. (b) The solubility of Al(OH) 3 is 5.5???10 ?9 mol/L. Solution a) FeCO3 <--> Fe+2 + CO3-2 s s molar mass of FeCO3 = 115.9 g/mol s = (5.6*10^-4)/(molar mass of FeCO3) = (5.6*10^-4)/115.9 = (4.83*10^-6) Ksp = [Fe+2]*[CO3-2] = s*s = s^2 = (4.83*10^-6)^2 = 2.33*10^-11 b) Al(OH)3 <--> Al+3 + 3OH- s 3s Ksp = [Al+3]*[OH-]^3 = s*(3s)^3 = 27*s^4 = 27*(5.5*10^-9)^4 = (2.47*10^-32) .