Magnesium hydroxide, Mg(OH)2(s), has Ksp=5.6×10−12 at 25 °C.
(a) Calculate the molar solubility of Mg(OH)2 in pure water at 25 °C.
(b) A student adds solid NaOH until the initial hydroxide-ion concentration is 0.010 M. Calculate the molar solubility of Mg(OH)2 under these basic conditions.
(c) Another student claims that, in part (b), the hydroxide produced by Mg(OH)2 dissolution is negligible compared with the 0.010 M added. Evaluate this approximation quantitatively.
(d) Determine the percentage error in the solubility value that would result if the approximation in part (c) were accepted.