Two separate beakers each contain of a buffered solution at and

CHEMISTRY · Multi-part · AP · Chemistry · Acids and Bases · Acids and Bases

Problem

Two separate beakers each contain

500\,\text{mL}

of a buffered solution at

\text{pH}=9.00

and

25\ ^\circ\text{C}

. Equal masses of the two salts listed below are added, and each mixture is allowed to reach equilibrium. •

\text{Mg(OH)}_2

with

K_{sp}=5.6\times10^{-12}

•

\text{PbI}_2

with

K_{sp}=1.4\times10^{-8}

Assume the volume change upon adding the salts is negligible. (a) Calculate the molar solubility of

\text{Mg(OH)}_2

in the buffered solution. (b) Calculate the molar solubility of

\text{PbI}_2

in the same buffered solution. (c) Rank the two salts from higher to lower equilibrium molar solubility at

\text{pH}=9.00

. Briefly justify your answer based on the values obtained in parts (a) and (b).