Ksp applicationHardQuestion 600439
Question
The solubility of CaF₂ (Ksp = 3.4×10⁻¹¹) in 0.1 M NaF solution (common ion effect) is:
- A3.4×10⁻⁹ MCorrect
- B1.84×10⁻⁵ M
- C3.4×10⁻⁸ M
- D3.4×10⁻¹¹ M
Correct answer
3.4×10⁻⁹ M
Explanation
CaF₂ ⇌ Ca²⁺ + 2F⁻. With [F⁻] ≈ 0.1 M (from NaF): Ksp = s × (0.1)² → s = 3.4×10⁻¹¹/0.01 = 3.4×10⁻⁹ M. Much less than in pure water (s ≈ 2×10⁻⁴ M).