Question

What is the molar solubility of calcium fluoride ( CaF2) in water? The solubility-product constant for CaF2 is 3.9 ⋅ 10-11 at 25 °C. What is the molar solubility of calcium fluoride ( CaF2) in water? The solubility-product constant for CaF2 is 3.9 10-11 at 25 °C. 3.4 ⋅ 10-4 8.8 ⋅ 10-6 3.1 ⋅ 10-6 1.3 ⋅ 10-11 2.1 ⋅ 10-4

Answer 1

Answer:

The molar solubility of calcium fluoride ( CaF₂) in water = 2.1×10⁻⁴ M

Explanation:

Given:

The solubility product constant of Calcium fluoride = 3.9×10⁻¹¹

To find the solubility of Calcium fluoride in water.

Consider the ICE take for the solubility of the solid, CaF₂ as:

                                  CaF₂    ⇄     Ca²⁺ +    2F⁻

At t=0                            x                 -              -

At t =equilibrium         x-s                s           2s          

The expression for Solubility product for CaF₂ is:

$K_{sp}=\left[Ca^{2+} \right]\left[F^{-} \right]^2$

Applying values from the table as:

$K_{sp}=s\times (2s)^2$

$3.9\times 10^{-11}=4s^3$

$s=2.1\times 10^{-4}\ M$

Thus, solubility = 2.1×10⁻⁴ M