PART A: Mg(OH)2 is a sparingly soluble salt with a solubility product, Ksp, of 5.61x10^-11. It is used to control the pH and provide nutrients in the biological (microbial) treatment of municipal wastewater streams. Calculate the ratio of solubility of Mg(OH)2 dissolved in pure H2O to Mg(OH)2 dissolved in a 0.180 M NaOH solution? Express your answer numerically to three significant figures.
PART B: What is the pH change of a 0.300 M solution of citric acid (pKa=4.77) if citrate is added to a concentration of 0.160 M with no change in volume? Express the difference in pH numerically to two decimal places.