What is the minimum concentration of CN^-(aq) that will prevent the precipitation of AgX(s) from a solution that is 0.149 M in X^-(aq) and 0.0184 M in Ag⁺(aq) ?
(K_sp for AgX(s) = 5.2 × 10^-17;K_f for Ag(CN) ₂^- = 5.6 × 10¹⁸)

Question

Quizplus · Accepted Answer

To prevent the precipitation of AgX(s), the product of the concentrations of Ag+ and X- in solution must be less than the solubility product constant (Ksp) for AgX, which is 5.2 × 10^-17. The formation constant (Kf) for Ag(CN)2^- is 5.6 × 10^18, indicating that Ag+ will strongly complex with CN- to form Ag(CN)2^-. This complexation reduces the concentration of free Ag+ ions in solution, thus preventing the precipitation of AgX. The minimum concentration of CN- needed can be calculated using the Kf for Ag(CN)2^- and the initial concentration of Ag+. The correct calculation leads to a concentration of 3.1 × 10^-3 M CN-, which is option A.

What Is the Minimum Concentration of CN-(aq)that Will Prevent the Precipitation

What Is the Minimum Concentration of CN^-(aq)that Will Prevent the Precipitation