AP Chemistry
Notes: Solubility Product (15.5-15.8)
Solubility Product Constant:
A special case of equilibrium involving dissolving.
Solid  Positive Ion + Negative Ion
Mg(NO3)2(s)  Mg2+(aq) + 2NO3-(aq)
Keq = Ksp =
Because the constant is a product of solubility, we call it the solubility product constant, Ksp
Types
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of solubility product problems:
Given Ksp, find solubility
Given solubility, find Ksp
Find solubility in a solution with a common ion
Predicting precipitation
Example: BaF2(S)  Ba+2(aq) + 2F-(aq)
Write out the equilibrium law expression…
Some solubility generalizations:
 All ____________________________ are soluble
 All compounds of the ___________________________ are soluble (Li, Na, K, etc.)
 All compounds of the ammonium (__________) are soluble
Example: Given Ksp, Find Solubility - What is the solubility of Silver Bromide (Ksp = 5.2 x 10-13)
Example: Given Ksp, Find Solubility - What is the solubility of PbI2 (Ksp = 7.1 x 10-9)
Example: Find Ksp Given Solubility - What is the Ksp of Boric Acid, given its solubility of 2.15 x 10-3
Moles/liter?
AP Chemistry
Notes: Solubility Product (15.5-15.8)
Example: Solubility with a Common Ion - What is the solubility of lead iodide (PbI2) in a .15M solution
of KI ?
Example: Predicting Precipitation - A student mixes 0.010 mole Ca(NO3)2 in 2 liters of 0.10M Na2C03
solution. Will a precipitate form?
Step 1: Write out the dissolving equations
Step 2: Determine the most likely precipitate & write out it’s equation.
Step 3: Determine the molar concentrations & calculate the reaction quotient (Q).
In this case, reaction quotient (Q) is the product of the Ksp equation using the ion concentration
before any reaction interaction. If Q > Ksp Then a precipitate will form.
Example: Predicting Precipitation -.015 moles of AgNO3 is mixed with 5 liters of .02M NaCl solution.
What is the most likely precipitate and will it form?