Solubility Products

0:00 / 0:00

Solubility and Ksp
Recall that a saturated solution is one that has the maximum quantity of solute dissolved. It is at this point that an equilibrium forms between the solid and the dissolved ions. 
Ex: AgCl(s)  ⇌  Ag+(aq) + Cl-(aq)
Increasing temperature can cause the solubility to increase


PAGE BREAK
Ksp= The solubility product constant
It is the equilibrium constant (K) that is specifically for saturated solutions
Write the Ksp expression for the above reaction in equilibrium:
 

Ksp=[Ag+][Cl-]

Watch Out!
Remember that solids or liquids are never included in any K expression!


For these solids, we can write out ICE tables similar to how we did earlier:

Let's say the Ksp=1.8x10-10 for the AgCl(s) at 25oC and we start with 0.2M of AgCl(s). We could be asked to find the concentrations for the ions at equilibrium.
1) Create an ICE Table 

2) Write out a Ksp expression and solve for x:
Ksp=[Ag+][Cl-]
1.8x10-10=x2
x=1.34x10-5 M = [Ag+]=[Cl-]

Wize Tip
If you are ever asked to solve for the "molar solubility" or "solubility" of a salt, they are asking you to solve for x like we just did! 
Solubility is referring to how much of a solid dissolves to give a saturated solution (at equilibrium)

0:00 / 0:00

Express the Ksp for the following salts

a) NaOH(s)

b) MgF2

c)  Al2S3

a) 𝐾𝑠𝑝 = [𝑁𝑎+][𝑂𝐻−]

b) 𝐾𝑠𝑝 = [𝑀𝑔2+][𝐹−]2

c) 𝐾𝑠𝑝 = [𝐴𝑙3+]2[𝑆2−]3

The solubility of copper(II) arsenate, Cu3(AsO4)2, in pure water is 3.7×10-8 M. Calculate the value of Ksp for copper(II) arsenate from this data. 

6.9×10−386.9\times10^{-38}6.9×10−38

4.2×10−374.2\times10^{-37}4.2×10−37

2.5×10−362.5\times10^{-36}2.5×10−36

3.7×10−363.7\times10^{-36}3.7×10−36

7.5×10−367.5\times10^{-36}7.5×10−36

I don't know

Wize University Chemistry Textbook > Other Examples of Equilibria (ex. Solubility)

Popular Courses

Solubility and Ksp

Extra Practice

Molar Solubility Problem #1

Molar Solubility

Solubility: Calculate Ksp

Solubility: Calculating Molar Solubility