Practice question
Question
The Ksp of CaCO₃ is 3.8 × 10⁻⁹ . What is [Ca²⁺] in a saturated solution with 0.02 M Na₂CO₃ ?
Explanation
For CaCO₃ <=> Ca²⁺ + CO₃²⁻ , Ksp = [Ca²⁺][CO₃²⁻] = 3.8 × 10⁻⁹ , [CO₃²⁻] ≈ 0.02 , [Ca²⁺] = (3.8 × 10⁻⁹/0.02) = 1.9 × 10⁻⁷ M .