Question

Solid NaI is slowly added to a solution that is .010M in Cu+ and .010M in Ag+...
a.) which compound will precipitate first
b.) calculate [Ag+] when CuI just begins to precipitate
c.)what % of Ag+ remains in solution.

Answer 1

AgI precipitates first because it has lower Ksp and lower solubility:
Ksp =[ Ag+][I-] = 1.5x10^-16
[0.010][I-] = 1.5x10^-16
[I-] = 1.5x10^-14 when AgI begins to precipitate.

Ksp = [Cu+][i-] = 5.3x10^-12 for CuI
[0.010][I-] = 5.3x10^-12
[I-] = ?___ when CuI begins to precipitate.

[Ag+][5.32x10^-10]=1.5x10^-16
[Ag+] = ?___
% Ag+ in solution = (100)[Ag+]/ (0.010)