solubility product - Ksp  

• equals product of ion concentrations raised to the power of their coefficients
• can be used to calculate solubility (g/L)

Find the Ksp for a saturated solution of Mg(OH)2 if the pH is 10.17  

• assume that Mg(OH)2, a strong base, dissociates completely
• Mg(OH)2 >> Mg2+ + 2OH-
• pOH = 14 - pH = 14 - 10.17 = 3.83
• [OH-] = 10-pOH = 10-3.83 = 1.48 x 10-4
• [Mg2+] = [OH-] / 2 = 7.4 x 10-5
• Ksp = [Mg2+] [OH-]2 = 1.62 x 10-12

Find the molar solubility of Mn(OH)2 if the Ksp is 1.6 x 10-13  

• Mn(OH)2 >> Mn2+ + 2OH-
• Ksp = [Mn2+] [OH-]2
• let c = molar solubility, concentration of Mn
• Ksp = c x (2c)2 = 4c3
• 1.6 x 10-13 = 4c3
• c = 3.4 x 10-5

Find the molar solubility of Ba(IO3)2 in a solution of 0.010 M NaIO3  

• Given:
  • Ksp = 6 x 10-10
• [IO3-] = [NaIO3] = 0.010
• Ksp = [Ba2+] [IO3-]2
• 6 x 10-10 = [Ba2+] (0.010)2
• [Ba2+] = molar solubility = 6 x 10-6

Find the molar solubility of Ba(IO3)2 in a solution of 0.01 M NaNO3  

• Given:
  • Ksp = 6 x 10-10
• NaNO3 has no effect on the solubility of Ba(IO3)2
• Ksp = [Ba2+] [IO3-]2
• let c = molar solubility, concentration of Ba
• Ksp = c x (2c)2 = 4c3
• 6 x 10-10 = 4c3
• c = 5.3 x 10-4