Calcium sulfate dihydrate, (s) (commonly called gypsum)

CHEMISTRY · Multi-part · AP · Chemistry · Equilibrium · Equilibrium

Problem

Calcium sulfate dihydrate,

\text{CaSO}_4\cdot2\text{H}_2\text{O}

(s) (commonly called gypsum), has a solubility‐product constant

K_{sp} = 2.4\times10^{-5}

25\,^{\circ}\text{C}

. A laboratory prepares

250\,\text{mL}

of an aqueous solution that is initially

0.010\,\text{M}

\text{Ca(NO}_3)_2

. (a) Write the balanced dissolution equation for

\text{CaSO}_4\cdot2\text{H}_2\text{O}

(s) in water, including physical states. (b) Determine the molar solubility of

\text{CaSO}_4\cdot2\text{H}_2\text{O}

in the

0.010\,\text{M}

\text{Ca(NO}_3)_2

solution at

25\,^{\circ}\text{C}

. (c) Calculate the mass, in grams, of

\text{CaSO}_4\cdot2\text{H}_2\text{O}

that can dissolve in the

250\,\text{mL}

portion of the

\text{Ca(NO}_3)_2

solution before the solution becomes saturated. (d) Briefly discuss how, if at all, doubling the initial

\text{Ca}^{2+}

concentration would affect the amount of

\text{CaSO}_4\cdot2\text{H}_2\text{O}

that can dissolve. Justify your answer qualitatively without additional numerical calculation.