Given the solubility, calculate the solubility product constant (ksp) of each salt at 25°c: (a) ag2so3, s = 4.6 × 10−3 g/l; (b) hg2i2, s = 1.5 × 10−7 g/l; (c) zn3(po4)2, s = 5.9 × 10−5 g/l.
Part (a): Reaction of the compound is given by: Ag₂SO₃ ⇄ 2 Ag⁺ + SO₃²⁻ Solubility is given as: s = 4.6 x 10⁻³ g/L molar solubility = (4.6 x 10⁻³) / 295.79 = 1.55 x 10⁻⁵ mol /L solubility product is written as: Ksp = [Ag⁺]² [SO₃²⁻] = [2 x 1.55 x 10⁻⁵]² * [1.55 x 10⁻⁵] = 1.489 x 10⁻¹⁴
Part (b): Reaction of the compound is given by: Hg₂I₂ ↔ Hg₂²⁺ + 2 I⁻ Solubility is given as: S = 1.5 x 10⁻⁷ g / L Molar solubility = 1.4 x 10⁻⁷/ 654.98 = 2.29 x 10⁻¹⁰ mol/L solubility constant is written as: Ksp = [Hg₂²⁺][I⁻]² = (2.29 x 10⁻¹⁰) (2 x 2.29 x 10⁻¹⁰)² = 4.8 x 10⁻²⁹
Part (c): Reaction of the compound is given as: Zn₃(PO₄)₂ ↔ 3 Zn²⁺ + 2 PO₄³⁻ solubility is given as: s = 5.9 x 10⁻⁵ g / L Molar solubility = 5.9 x 10⁻⁵ / 386.11 = 1.52 x 10⁻⁷ mol / L Solubility constant is written as: Ksp = [Zn²⁺]³ [PO₄³⁻]² = (3 x 1.52 x 10⁻⁷)³ * (2 x 1.52 x 10⁻⁷)² = 8.76 x 10⁻³³
