1. Lesson 7: Predicting Precipitate Formation
Unit 3: Solubility
Lesson 7: Predicting Precipitate Formation

2. The Trial Ion Product
Last unit, we used a trial Keq called the reaction quotient (Q). In this unit we will use a trial Ksp called the trial ion product (Q).
Q = the product of ion concentrations that exists (what we have)
Ksp = the product of ion concentrations that is needed to establish equilibrium (what we need to form a saturated solution)

3. Think-Pair-Share Predict what will happen when: Q < Ksp Q = Ksp
TPS – 5 min

4. Calculations Involving Q
Example 1 (Try it!): Will a precipitate form when 5.0 mL of 6.0x10-5 M Ag+ mixes with 10.0 mL of 4.2x10-6 M Cl-? (Hint: Note that when the two solutions are mixed they dilute each other!)
“We do” – 15 min

6. Calculations Involving Q
Example 2: If 25.0 mL of 4.50x10-3 M Pb(NO3)2 is mixed with 35.0 mL of 2.80x10-3 M MgI2, will a precipitate form?
Example 3: What [Cl-] is required to just start precipitation of AgCl(s) from a 3.6x10-3 M solution of Ag+?
“I do” – 20 min
#2 – dilution calc, then find Q
#3 – Q = Ksp, solve for [Cl-]

7. Homework
Pg. 98 #56-68 even numbers
10 min