NEETChemistryIonic Equilibrium
Calculate the solubility of PbSO ₄ in a 0.05 M solution of Al ₂( SO ₄)₃ . (Given: K_ sp of PbSO ₄ = 1.5 10⁻⁸ )
Options
- A3.0 10⁻⁷ M
- B1.0 10⁻⁷ M
- C1.5 10⁻⁷ M
- D6.67 10⁻⁷ M
Correct answer
B. 1.0 10⁻⁷ M
Step-by-step solution
The strong electrolyte Al ₂( SO ₄)₃ dissociates completely in solution: Al ₂( SO ₄)₃ 2 Al ³⁺ + 3 SO ₄²⁻ The concentration of the common ion, [ SO ₄²⁻] = 3 0.05 M = 0.15 M . For the sparingly soluble salt PbSO ₄ : PbSO ₄(s) Pb ²⁺(aq) + SO ₄²⁻(aq) Let the solubility of PbSO ₄ in this solution be s . The solubility product expression is: K_ sp = [ Pb ²⁺][ SO ₄²⁻] Substituting the values (neglecting the small amount of SO ₄²⁻ from PbSO ₄ ): 1.5 10⁻⁸ = s (0.15) s = 1.5 10⁻⁸ 0.15 = 1.0 10⁻⁷ M Answer: 1.0 10⁻⁷ M