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

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)

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

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

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-]

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