(a) I f t he molar solubility of CaF2 at 35 C i s 1.24 * 10-3 mol>L, what is Ksp at this temperature?

Verified step by step guidance

1. Identify the dissolution equation for calcium fluoride: \( \text{CaF}_2 (s) \rightleftharpoons \text{Ca}^{2+} (aq) + 2\text{F}^- (aq) \).
2. Write the expression for the solubility product constant \( K_{sp} \) for the dissolution of \( \text{CaF}_2 \): \( K_{sp} = [\text{Ca}^{2+}][\text{F}^-]^2 \).
3. Recognize that the molar solubility of \( \text{CaF}_2 \) is given as \( 1.24 \times 10^{-3} \) mol/L, which represents the concentration of \( \text{Ca}^{2+} \) ions in solution.
4. Determine the concentration of \( \text{F}^- \) ions, which is twice the molar solubility of \( \text{CaF}_2 \), because each formula unit of \( \text{CaF}_2 \) produces two \( \text{F}^- \) ions.
5. Substitute the concentrations of \( \text{Ca}^{2+} \) and \( \text{F}^- \) into the \( K_{sp} \) expression and solve for \( K_{sp} \).

Key Concepts

Molar Solubility

Molar solubility refers to the maximum amount of a solute that can dissolve in a given volume of solvent at a specific temperature, expressed in moles per liter (mol/L). In the case of CaF2, the molar solubility indicates how much calcium fluoride can dissolve in water before reaching saturation.

Solubility Product Constant (Ksp)

The solubility product constant (Ksp) is an equilibrium constant that quantifies the solubility of a sparingly soluble ionic compound. It is calculated from the concentrations of the ions in a saturated solution, raised to the power of their coefficients in the balanced dissolution equation. For CaF2, Ksp is derived from the concentrations of Ca²⁺ and F⁻ ions.

Dissociation of Ionic Compounds

When ionic compounds like CaF2 dissolve in water, they dissociate into their constituent ions. For CaF2, the dissociation can be represented as CaF2(s) ⇌ Ca²⁺(aq) + 2F⁻(aq). Understanding this dissociation is crucial for calculating Ksp, as it directly relates the molar solubility to the concentrations of the ions produced in solution.