The K_sp for Mn(OH)₂ is 2.0 * 10^-¹³. At what pH will Mn(OH)₂ begin to precipitate from a solution in which the initial concentration of Mn²⁺ is 0.10 M?

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Quizplus · Accepted Answer

To find the pH at which Mn(OH)₂ begins to precipitate, use the Ksp expression: Ksp = [Mn²⁺][OH⁻]². Given Ksp = 2.0 × 10⁻¹³ and [Mn²⁺] = 0.10 M, solve for [OH⁻]: [OH⁻] = √(Ksp / [Mn²⁺]) = √(2.0 × 10⁻¹³ / 0.10) = √(2.0 × 10⁻¹²) = 1.41 × 10⁻⁶ M. Convert [OH⁻] to pOH: pOH = -log(1.41 × 10⁻⁶) ≈ 5.85. Then, pH = 14 - pOH = 14 - 5.85 = 8.15.

The Ksp for Mn(OH)2 Is 2

The K_sp for Mn(OH)₂ Is 2