The concentration of Pb²⁺ in an aqueous solution is 5.5 $\times$ 10^-3 M.What concentration of SO₄^2- is required to begin precipitating PbSO₄? The K_sp of PbSO₄ is 2.5 $\times$ 10^-8. A) 1.4 $\times$ 10^-10 M B) 4.5 $\times$ 10^-6 M C) 1.6 $\times$ 10^-4 M D) 8.3 $\times$ 10^-4 M E) 2.9 $\times$ 10^-2 M

Question

Quizplus · Accepted Answer

First, we need to write the balanced equation for the precipitation reaction:

PbS + SO4^2- → PbSO4 + S^2-

Before the reaction can occur, the concentrations must exceed the solubility product constant (Ksp) of PbSO4:

[Ksp] = [Pb2+][SO4^2-] = 2.5 x 10^-8 M

Next, we need to determine the concentration of SO4^2- needed to exceed this Ksp:

[SO4^2-] = [Pb2+][SO4^2-] / [PbS] = (5.5 x 10^-10 M)(2.5 x 10^-8 M) / (5.5 x 10^-10 M) = 2.5 x 10^-8 M

This concentration is equivalent to answer choice B. Therefore, the correct answer is B.

The Concentration of Pb2+ in an Aqueous Solution Is 5 ×\times×

The Concentration of Pb²⁺ in an Aqueous Solution Is 5 $\times$