Find the concentration of calcium ions in a solution made by adding 3.50 g of calcium fluoride to 750. mL of 0.125 M NaF. [For CaF₂, K_sp = 3.95 * 10^-11.]

Question

Quizplus · Accepted Answer

First, we need to calculate the moles of NaF in the solution:

moles NaF = (0.125 mol/L) x (0.750 L) = 0.09375 mol

Next, we need to determine the amount of CaF2 that dissolves in this solution. We can use the solubility product constant (Ksp) provided in the question:

Ksp = [Ca2+][F-]2 = (3.95 x 10^-11)

We know that the concentration of F- in the solution is 0.125 M (from the NaF added), so we can calculate the concentration of Ca2+:

[Ca2+] = Ksp/[F-]2 = (3.95 x 10^-11)/(0.125)^2 = 2.53 x 10^-9 M

Therefore, the answer is choice B, with a concentration of 2.53 x 10^-9 M.

Find the Concentration of Calcium Ions in a Solution Made