Calcium fluoride, CaF₂, dissolves in water according to the equilibrium
CaF₂(s) ⇌ Ca²⁺(aq) + 2 F⁻(aq)
The solubility–product constant at 25 °C is Ksp=3.9×10−11.
(a) Using the balanced equilibrium expression, calculate the molar solubility of CaF₂ in pure water at 25 °C. Show all reasoning and keep an appropriate number of significant figures.
(b) Convert the molar solubility obtained in part (a) to grams of CaF₂ that dissolve per liter of solution.
(c) Based on both the numerical value of Ksp and your calculated solubility, classify CaF₂ as soluble, sparingly soluble, or effectively insoluble in water at 25 °C. Justify your choice with explicit reference to the equilibrium concepts involved.