Magnesium hydroxide is sometimes added to wastewater streams to raise the pH. Relevant thermodynamic data at 25 °C are provided below.
Ksp[Mg(OH)2] = 5.6×10−12
Answer the following questions about the solubility of Mg(OH)2 under different conditions.
(a) Calculate the molar solubility of Mg(OH)2 in pure water at 25 °C.
(b) The pH of a particular wastewater sample is adjusted to 12.00 before Mg(OH)2 is added. Calculate the molar solubility of Mg(OH)2 in this solution at 25 °C.
(c) Compare the results from parts (a) and (b). State whether the solubility increases, decreases, or remains the same upon raising the pH to 12.00, and provide a brief chemical explanation for the trend you observe.