Question

A solution contains 0.018 mol each of I– , Br– , and Cl– . Use the Ksp values given below to determine how much AgCl(s) precipitates out when this solution is mixed with 200 mL of 0.24 M AgNO3.

Answer 1

AgI , Ksp = 8.52×10^–17

AgBr , Ksp = 5.35×10^–13

AgI , Ksp = 1.77×10^–10

AgNO3 (aq) + Cl- (aq) ---------------------> AgCl (s) + NO3- (aq)

Ksp of AgI and AgBr are lesser than AgCl so they could form precipitate first

actual moles of AgNO3 are present = 200 x 0.24 / 1000 = 0.048

moles of each ion present 0.018

AgNO3 moles needed for I- = 0.018

AgNO3 moles needed for Br- = 0.018

remaining AgNO3 moles = 0.048 -(0.018 +0.018)

                                        = 0.012

now AgCl precipitation.

AgNO3 (aq) + Cl- (aq) ---------------------> AgCl (s) + NO3- (aq)

0.012                 0.018                                    0.012

moles of AgCl formed = 0.012

mass of AgCl formed = moles x molar mass

                                    = 0.012 x 143.32

                                     = 1.72 g

AgCl(s) precipitates = 1.72 g