1. The Solubility Product Principle
Equilibrium of Solids
The Solubility Product Principle

2. SOLUBILITY EQUILIBRIA (The Solubility-Product Constant, Ksp)
Well – I have good news and bad news for you…which do you want first???

3. The bad news:
You know all those solubility rules that state a substance is ________? Insoluble substances are actually a little bit soluble after all…
Only the future attorneys among you read the fine print. Soluble is often defined as “greater than __grams dissolving in ____ mL of water”. So, there is a lot of wiggle room for solubility up to 3 grams! This type of equilibria deals with that wiggle room.
Sorry for “lying” to you…You just couldn’t handle the truth at that time!

4. The good news:
Solubility equilibrium is really a simple extension of ________ equilibrium.

5. Precipitates In reality:
a salt that is insoluble, which is evidenced by forming a solid, (___________), when two solutions are mixed just means that the solution is very saturated.
Precipitates form when the solution is ________________!

6. ________: the amount of compound that dissolves in a specified volume
________: the amount of compound that dissolves in a specified volume. Usually expressed as grams per Liter or grams per 100 mL
________________: number of moles of a compound that dissolve to give 1 Liter of saturated solution.

7. ________________________:
for a compound it is the product of the concentrations of its ions each raised to a power that corresponds to the number of ions formed.
Ksp chart is Table B.10 in your books
Works just like Kc and Kp

8. Ex. 1) a. What is the solubility product expression for the dissociation of calcium carbonate? (Ksp = solubility product constant.)

9. b. For aluminum fluoride?

10. c. For barium nitride?

11. Calculating Ksp from Solubility
Ex. 2) Copper(I) bromide has a measured solubility of 2.0 × 10−4 mol/L at 25°C. Calculate its Ksp value.

12. Ex. 3) Copper(II) hydroxide has a
Ksp = 1.6x10-19
a) Calculate the molar solubility
b) Find the concentrations of the constituent ions
c) Solve for the solubility in grams per liter of the copper(II) hydroxide

13. Ex. 4) Find [S2-] in saturated iron(III) sulfide Ksp = 1.40x10-88

14. SOLUBILITY AND THE COMMON ION EFFECT
________________________: the solubility of a compound is less in a solution that contains an ion common to the compound than it is in pure water.
Experiments show that the solubility of any salt is always less in the presence of a “common ion”.
Why? LeChâtelier’s Principle! Adding solids does not shift the equilibrium but you can always make more solids when reestablishing equilibrium.

15. Would magnesium hydroxide (milk of magnesia) be more soluble in magnesium chloride or water? Why?
Mg(OH)2(s)  Mg2+(aq) + 2 OH−(aq)

16. SOLUBILITY AND pH
The pH can also affect solubility. Evaluate the equation to see which species reacts with the addition of acid or base.
Would magnesium hydroxide be more soluble in an acid or a base? Why?
Mg(OH)2(s)  Mg2+(aq) + 2 OH−(aq)

17. Ex. 5) If 0. 750 M FeI3 is added to Ex. 4
Ex. 5) If M FeI3 is added to Ex What is the final concentration of iron and sulfur ions?

18. Ex. 6)
a. Calculate the molar solubility and ion concentrations of aluminum fluoride in pure water and its solubility in grams per 100 mL. Ksp = 6.4 x 10-19
b. Using the common ion effect, find the molar solubility of AlF3 in 0.20 M potassium fluoride solution along with the ion concentrations.
c. Compare the two molar solubilities.

19. Ex. 7) What is the solubility product constant if 0
Ex. 7) What is the solubility product constant if g of silver dichromate is dissolved in a one liter solution?

20. ________________________: a separation process that removes some ions from solution while leaving other ions with similar properties in the solution.

21. Ex. 8) Solid silver nitrate is slowly added to a solution that is 0
Ex. 8) Solid silver nitrate is slowly added to a solution that is M each in sodium bromide and sodium iodide. a) Calculate the [Ag+ ] required to initiate the precipitation of each silver halide. b) Which precipitates first? For AgBr: Ksp = 3.3 x For AgI: Ksp = 1.5 x c) The Ksp = 1.8 x for AgCl. Compare that to AgBr and AgI to determine which would precipitate last.

22. Ex. 9) Using your answer from #8, find the percentage of Iodine ions that precipitated before silver bromide precipitates.

23. Ex. 10) How many moles of bismuth(III) hydroxide will dissolve in 1
Ex. 10) How many moles of bismuth(III) hydroxide will dissolve in 1.00 L of a solution with a pH=4.77 Ksp = 3.2x10-40

24. Reaction Quotient in Precipitation Reactions
If Qsp < Ksp _______________________
No precipitation occurs; if solid is present, more solid can dissolve (________________)
If Qsp = Ksp _______________________
Solid and solution are in equilibrium; neither forward nor reverse process is favored.
If Qsp > Ksp _______________________
Precipitation occurs to form more solid (________________)