Solubility Lesson 7 Changing solubility

When to and When not to Multiply the Molarity   1. The molar solubility of Ba(OH)2 is 2. Equal volumes of 0.0010 M Ba(NO3)2 and 0.0010 M. Ksp = ? 0.0010 M NaOH are mixed. Will a precipitate occur? Do not multiply by 2 because of NaOH Ba(OH)2(s) ⇌ Ba2+ + 2OH- Ba(OH)2(s) ⇌ Ba2+ + 2OH- 1 2 1 2 s s 2s 0.0010 M 0.0010 M Multiply by 2 because of Ba(OH)2(s) 0.00050 M 0.00050 M TIP = [Ba2+][OH-]2 Ksp = [Ba2+][OH-]2 Ksp = [s][2s]2 TIP = [0.00050][0.00050]2 Ksp = 4s3 TIP = 1.25 x 10-10 Ksp = 4[0.0010]3 Ksp = 4.0 x 10-9 TIP < Ksp No ppt.

3. AgNO3(s) is added to 1.0 L of a solution containing Cl- in order to precipitate out the Cl- as AgCl(s). After the AgCl(s) is filtered out what is the remaining concentration of Cl-? AgCl(s) ⇌ Ag+ + Cl- s s s Ksp = s2 1.8 x 10-10 = s2 s = [Cl-] = 1.3 x 10-5 M

The molar solubility is the amount of PbCl2(s) in moles per litre that dissolves into ions to form a saturated solution. increases the molar solubility energy + PbCl2(s) ⇌ Pb2+ + 2Cl- decreases the molar solubility Solid equilibriums are endothermic. Only changing the temperature changes the Ksp.

Changing the Solubility of a Salt energy + AgCl(s) ⇄ Ag+ + Cl- Substance Added Molar Solubility Ksp Effect AgNO3 Decrease none NaCl Decrease none Na2S Increase 2Ag+ + S2- → Ag2S(s) none Pb(NO3)2 Increase Pb2+ + 2Cl- → PbCl2(s) none

Changing the Solubility of a Salt energy + AgCl(s) ⇄ Ag+ + Cl- Substance Added Molar Solubility Ksp Effect H2O none moles/L does not change none AgCl none solid none Increase Temperature Increase Increase Decrease Temperature Decrease Decrease

Changing the Solubility of a Salt Ca(OH)2(s) ⇄ Ca2+ + 2OH-   Ca(OH)2(s) ⇄ Ca2+ + 2OH- Substance Added Effect on Molar Solubility Effect on Ksp none Ca(NO3)2 Decrease Na2SO4 Increase none NaOH Decrease none HCl Increase none NaCl none none none none Ca(OH)2 Increase Temperature Increase Increase Decrease Temperature Decrease Decrease

1. Mg(OH)2 will have the greatest solubility in: Mg(OH)2(s) ⇌ Mg2+ + 2OH- A. NaOH B. Mg(NO3)2 C. H2O OH- lowers solubility Mg2+ lowers solubility No effect solubility D. AgNO3 Ag+ increases solubility by reacting with OH-