What is the minimum concentration of CN- 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)? (Ksp for AgX(s) = 5.2 × 10^-17; Kf for Ag(CN)^2- = 5.6 × 10¹⁸)

Question

Quizplus · Accepted Answer

The correct answer is A because the minimum concentration of CN- 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) is 3.1 × 10-3 M. This can be calculated using the following equation:Ksp = [Ag+][X-]Kf = [Ag(CN)2-]/[Ag+][CN-]2[Ag(CN)2-] = Kf[Ag+][CN-]2[CN-] = sqrt(Ksp/[Kf][Ag+][X-])[CN-] = sqrt(5.2 × 10-17/[5.6 × 1018][0.0184][0.149])[CN-] = 3.1 × 10-3 M

What Is the Minimum Concentration of CN- That Will Prevent