Answer:
2.4 × 10⁻⁴ M
Explanation:
Step 1: Calculate the concentration of Mg²⁺ coming from Mg(NO₃)₂
Mg(NO₃)₂ is a strong electrolyte and the molar ratio of Mg(NO₃)₂ to Mg²⁺ is 1:1. The initial molar concentration of Mg²⁺ is 1/1 × 0.36 M = 0.36 M.
Step 2: Make an ICE chart for the solution of MgF₂
MgF₂(s) ⇄ Mg²⁺(aq) + 2 F⁻(aq)
I 0.36 0
C +S +2S
E 0.36+S 2S
The solubility product constant is:
Ksp = [Mg²⁺] × [F⁻]² = (0.36+S) × (2S)²
Since S <<< 0.36, 0.36+S ≈ 0.36.
Ksp = 0.36 × 4S² = 8.4 × 10⁻⁸
S = 2.4 × 10⁻⁴ M
