Use Molar Concentrations to Calculate Ion Product/Compare to Ksp

Question

20.00 mL of a 0.077 M solution of silver nitrate, AgNO3, is mixed with 30.00 mL of a 0.043 M solution of sodium acetate, NaC2H3O2. Does a precipitate form? The Ksp of AgC2H3O2 is 2.5*10^-3. Include the calculate ion product in your answer.

Answer 1

AgNO₃(aq) + NaC₂H₃O₂(aq) ==> AgC₂H₃O₂(aq or s) + NaNO₃(aq)

AgC₂H₃O₂ (s) ==> Ag+(aq) + C₂H₃O₂^-

After mixing, final volume = 20 ml + 30 ml = 50 ml = 0.05 L

Q = [Ag⁺][C₂H₃O₂^-]

[Ag⁺] = 0.020 L x 0.077 mol/L = 0.00154 mols / 0.05 L = 0.0308 M

[C₂H₃O₂^-] = 0.030 L x 0.043 mol/L = 0.00129 mols / 0.05 L = 0.0258 M

Q = (0.0308)(0.0258) = 0.000795 = 7.95x10^-4

Comparing Q to Ksp, we see that Q < Ksp therefore a precipitate WILL NOT form.