1. More Ksp applications

2. Common Ion Effect Solution contains the ion of the dissolving salt.
One of the ions that was in the original Ksp expression is added to the system at equilibrium
Instead of both ions having an initial concentration of 0, one will have a value

3. Common Ion Effect Solution contains the ion of the dissolving salt.
Example: You mix Ag2CrO4 with a M solution of AgNO3
Ksp of Ag2CrO4 = 9.0 x 10-12

4. Common Ion Effect
Example: You mix Ag2CrO4 with a M solution of AgNO3
Common ion: Ag+
Ignore the NO3-

5. Common Ion Effect Ag2CrO4 <==> 2Ag+ + CrO42- I 0.100 0 C E
+2x +x
x x

6. Common Ion Effect Ag2CrO4 <==> 2Ag+ + CrO42- E .100 + 2x x
9.0 x = [ x]2 [x]

7. Common Ion Effect Ag2CrO4 <==> 2Ag+ + CrO42- E .100 + 2x x
9.0 x = [ x]2 [x]
= [.100]2 [x] assume very small

8. Common Ion Effect Ag2CrO4 <==> 2Ag+ + CrO42- E .100 + 2x x
9.0 x = [ x]2 [x]
= [.100]2 [x]
= .01x

9. Common Ion Effect Ag2CrO4 <==> 2Ag+ + CrO42- E .100 + 2x x
9.0 x = [ x]2 [x]
= [.100]2 [x]
= .01x
9 x = x % rule?

10. Common Ion Effect Ag2CrO4 <==> 2Ag+ + CrO42- E .100 + 2x x
Ag+ = (9 x 10-10) = .100
CrO42- = 9 x 10-10

11. Common Ion Effect
What effect does this have according to Le Chatelier’s principle?
Addition of ion (product) shifts equilibrium to the left
So what does a common ion always do to solubility?
LOWER solubility

12. Common Ions – Your Turn Al2(C2O4)3 (s)  2 Al3+ + 3 C2O42-
Ksp = 6.33 x 10-19
What is the solubility of aluminum if M sodium oxalate solution is added to the system at equilibrium?

13. Precipitate Formation?
Will a precipitate form when you mix 2 solutions together?

14. Precipitate Formation?
Not equilibrium or maybe it is. Not sure, use Q.
Need to find new [ ] after mixing and plug into Q

15. Precipitate Formation?
A solution is prepared by adding mL of 4.00 x 10-3 M Ce(NO3)3 to mL of 2.00 x 10-2 M KIO Will Ce(IO3)3 precipitate from this solution? (Ksp of Ce(IO3)3 = 1.9 x 10-10)

16. Precipitate Formation?
A solution is prepared by adding 750 mL of 4.00 x 10-3 M Ce(NO3)3 to mL of 2.00 x 10-2 M KIO3. Will Ce(IO3)3 precipitate from this solution? (Ksp of Ce(IO3)3 = 1.9 x 10-10)
Ce3+: 4.00 x 10-3 M = x mol  mol Ce3+ =
0.750 L L
IO3- : 2.00 x 10-2 M = x mol  mol IO3- =
0.300 L L

17. Precipitate Formation?
A solution is prepared by adding 750 mL of 4.00 x 10-3 M Ce(NO3)3 to mL of 2.00 x 10-2 M KIO3. Will Ce(IO3)3 precipitate from this solution? (Ksp of Ce(IO3)3 = 1.9 x 10-10)
Ce3+ = 2.86 x 10-3
IO3-1 = 5.71 x 10-3

18. Precipitate Formation?
A solution is prepared by adding 750 mL of 4.00 x 10-3 M Ce(NO3)3 to mL of 2.00 x 10-2 M KIO3. Will Ce(IO3)3 precipitate from this solution? (Ksp of Ce(IO3)3 = 1.9 x 10-10)
Q = [Ce3+ ] [IO3-]3
Q = [2.86 x 10-3][5.71 x 10-3]3
Q = 5.32 x 10-10

19. Precipitate Formation?
Ksp = 1.9 x vs Q = 5.32 x 10-10
If Q is > than Ksp then a precipitate forms (too many products, shift left TOWARDS precipitate)
If Q is < than Ksp then no precipitate
(too many reactants, shift right AWAY FROM precipitate)
In this case……. precipitate forms! (Q > K)

20. More Practice
Will a precipitate form when 75.0 mL of M BaCl2 and 125 mL of M Na2SO4 are mixed together?
Ksp BaSO4 = 1.48 x 10-9

21. Putting Them Together
We can now put together a solution stoichiometry problem WITH a Ksp common ion problem!! Yay!!!

22. Putting Them Together
Calculate the final concentrations of K+, C2O42-, Ba2+, and Br- in a solution prepared by adding L of M K2C2O4 to L of M BaBr2.
For BaC2O4, Ksp = 2.3 x 10-8
Absent? I’ll post a key to this on the website.