Question

Calculate Qsp for calcium fluoride (Ksp = 3.9 × 10⁻¹¹) when 240.0 mL of a 5.20 × 10⁻³ M solution of Ca(NO₃)₂ is added to 225.0 mL of a 5.80 × 10⁻³ M solution of KF.

Answer 1

To find the Qsp for calcium fluoride when Ca(NO3)2 is mixed with KF, calculate the final concentrations of Ca2+ and F- ions in the mixture, and then use the Qsp expression Qsp = [Ca2+][F-]^2 with the calculated concentrations to obtain the result.

Step-by-step explanation:

To calculate the solubility product (Qsp) for calcium fluoride (CaF2) when solutions of Ca(NO3)2 and KF are mixed, one must first determine the concentration of Ca2+ and F- ions in the combined solution.

The concentration of Ca2+ in the mixed solution is calculated by the formula C1V1 = C2V2, where C1 and V1 are the concentration and volume of the first solution, and C2 and V2 are the concentration and volume of the resultant mixed solution:

CCa(NO3)2 = (5.20 × 10−3 M) × (240.0 mL) / (240.0 mL + 225.0 mL) = 2.58 × 10−3 M

The concentration of F- after mixing is similarly calculated:

CKF = (5.80 × 10−3 M) × (225.0 mL) / (240.0 mL + 225.0 mL) = 2.81 × 10−3 M

Now, considering te dissolution reaction of calcium fluoride, CaF2(s) → Ca2+(aq) + 2F−(aq), we can write the expression for Qsp.