Catalyst It is found that 1.1 x 10-2 g of SrF2 dissolves per 100 mL of solution. Calculate the solubility product of SrF2. End

Acetate

Lecture 8.2 – Application of Ksp

Today’s Learning Targets LT 8.4 – I can hypothesize about which slightly soluble compound will precipirate first through utilization of the Ksp

Predicting Precipitation Recall, the reaction quotient (Q) can be used to determine the direction an equilibrium needs to shift in order to achieve equilibrium: Q > Ksp: Shift left and precipitate more Q < Ksp: Shift right and dissolve more Q = Ksp: Solution is at equilibrium Therefore, we can predict whether more or less solid will precipitate based on this answer

Class Example Does a precipitate form when 0.10 L of 8.0 x 10-3 M Pb(NO3)2 is added to 0.40 L of 5.0 x 10-3 M Na2SO4? Note – the Ksp of PbSO4 is 6.3 x 10-7

Table Talk Doe a precipitate form when 0.050 L of 2.0 x 10-2 M NaF is mixed with 0.010 L of 1.0 x 10-2 M Ca(NO3)2. KSP (CaF2) = 3.9 x 10^-11 All except BiI3

Selective Precipitation Oftentimes, we have solutions that contain multiple solubility equilibriums. We can selectively precipirate some of the compounds, but not all, by utilizing Ksp The smaller the Ksp of an ion, the more likely it will precipitate from solution first.

Class Example A solution contains 1.0 x 10-2 M Ag+ and 2.0 x 10-2 M Pb2+. When Cl- is added, both AgCl (Ksp = 1.8 x 10-10) and PbCl2 (Ksp = 1.7 x 10-5) can pre. What concentration of Cl- is necessary to begin precipitation of each salt? Which salt precipitates first?

Table Talk A solutions consists of 0.050 M Mg2+ and Cu2+. Which ion precipitates first when OH- is added? What concentration of [OH-] is needed to begin to precipitation of each cation? NOTE – Ksp of Mg(OH)2 is 1.8 x 10-11 and Ksp of Cu(OH)2 is 4.8 x 10-20. All except BiI3

INSERT FIGURE 17.23

Drill Baby Drill Drill – Calculating Molar Solubilities Drill – Predicting Precipitation Integrated Practice – Connecting Ksp to past Units

Closing Time Read 17.1, 17.4, 17.5, 17.6, and 17.7 Homework: Drills and Integrated Practice Exam Debrief – Thursday or Friday 3:30 – 4