General ChemistryHard

Solubility and solubility product

Ksp of AgCl is 1.8×10⁻¹⁰. Calculate molar solubility of AgCl in water and in 0.010 M NaCl.
AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq).
Given data
K<sub>sp</sub>(AgCl) = 1.8×10⁻¹⁰
Review the theory: Chimica Generale
Steps
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  1. In water: s = [Ag⁺] = [Cl⁻]. Ksp = s². s = √(Ksp).
  2. In 0.010 M NaCl: [Cl⁻]₀ = 0.010 M. Approx s << 0.010. s = Ksp/[Cl⁻].
Full worked solution
  1. In water: s = [Ag⁺] = [Cl⁻]. Ksp = s². s = √(Ksp).
    1.8×10−10\sqrt{1.8\times10^{-10}}
    s = √(1.8×10⁻¹⁰) = 1.34×10⁻⁵ M.
  2. In 0.010 M NaCl: [Cl⁻]₀ = 0.010 M. Approx s << 0.010. s = Ksp/[Cl⁻].
    1.8×10−10/0.0101.8\times10^{-10} / 0.010
    s = 1.8×10⁻¹⁰/0.010 = 1.8×10⁻⁸ M.
Result:Solubility in water: 1.34×10⁻⁵ M — in 0.010 M NaCl: 1.8×10⁻⁸ M (common ion effect).