1. Solubility 1 Saturated Solutions 1.Cannot dissolve any more solute 2.Contain undissolved solid 3.Ex: BaSO 4 BaSO 4 (s)  Ba 2+ (aq) + SO 4 2- (aq) K sp = [Ba 2+ ][SO 4 2- ]/[BaSO 4 ] K sp = [Ba 2+ ][SO 4 2- ]

2. Solubility 2

3. 3 Examples: Ca 3 (PO 4 ) 2 Calcium Carbonate Chromium (III)Hydroxide Discuss Magnitude of K sp Writing K sp

4. Solubility 4 1.NaCl has a solubility of 35.7 g/100 mL. What is the molar solubility and K sp ? (Ans: 6.10 M, 37.2) 2.CaCl 2 has a solubility of 74.5 g/100 mL. What is the molar solubility and K sp ? (Ans: 6.71 M, 1.21 X 10 3 ) K sp and Solubility

5. 5

6. Solubility 6 3.BaF 2 has a molar solubility of 0.0068 M. How many grams will dissolve in 600.0 mL? (Ans: 0.72 grams) 4.MgI 2 has a molar solubility of 5.32 M. How many grams will dissolve in 500.0 mL? (Ans: 740. grams) K sp and Solubility

7. Solubility 7 Calculating K sp 1.A saturated soln of AgCl is found to have an eq. concentration of Ag + 1.35 X 10 -5 M. Calculate K sp. (Ans: 1.82 X 10 -10.) 2.A saturated soln of MgF 2 is prepared. At eq. the concentration of Mg 2+ is measured to be 0.0012 M. Calculate K sp. (Ans: 6.9 X 10 -9 )

8. 8 6.The solubility of Fe(OH) 3 is 0.0079 g/L. a. Calculate the molar solubility (7.4 X 10 -5 M) b. Calculate K sp ? (Ans: 8.1 X 10 -16 ) c. Calculate how many grams will dissolve in 250 mL (0.0020 g) d. Explain whether you would you expect the freezing point of the solution to be higher, lower, or just about that of water. e. List the proper name of the compound.

9. 9 Calculating Solubility 7.The solubility of Al 2 (SO 4 ) 3 is 31.3 g/L. What is the K sp ? (Ans: 6.9 X 10 -4 ) 8. What is the solubility in g/100 mL of CaSO 4 if the K sp is 2.4 X 10 -5 ? (Ans: 0.067 g/100 mL) 9.What is the solubility of CaF 2 in g/100 mL if the K sp is 3.9 X 10 -11 ? (Ans: 0.0016 g/100mL)

10. Solubility 10 Calculating Solubility 10. The K sp of Cu(N 3 ) 2 is 6.3 X 10 -10. How many grams of Cu(N 3 ) 2 will dissolve in 500 mL? (Ans: 0.0399 grams) Cu(N 3 ) 2 (s)   Cu 2+ (aq) + 2N 3 - (aq)

11. Solubility 11 Common Ion Effect and Solubility Common Ions decrease solubility CaF 2 (s)  Ca 2+ (aq) + 2F - (aq) a) Add Ca 2+ (shifts to reactants) b) Add F - (shifts to reactants) “Real world” water samples are usually not pure

12. Solubility 12 Hard Water – Contains high concentration of Ca 2+ and Mg 2+. a) Comes from minerals b) CaCO 3 buildup CaCO 3 (s)  Ca 2+ (aq) + CO 3 2- (aq) c) Does not lather well Common Ion Effect and Solubility

13. Solubility 13 Common Ion Effect and Solubility

14. Solubility 14 Soft Water a)Few minerals b)Often lathers too well c)Mg 2+ and Ca 2+ replaced by Na + Sulfur Water Contains high concs. Of SO 4 2- and SO 3 2- (turn to H 2 S) Common Ion Effect and Solubility

15. Solubility 15 1.Calculate the molar solubility of CaF 2 in a solution that is 0.010 M Ca(NO 3 ) 2. (Ans: 3.1 X 10 -5 M.) 2.Calculate the molar solubility of CaF 2 in a solution that is 0.010 M NaF. (Ans: 3.9 X 10 -7 M.) Common Ion Effect and Solubility

16. 16 What is the molar solubility of Mn(OH) 2 in 0.020 M NaOH? (Ans: 4.0 X 10 -10 )

17. Solubility 17 Applications 1.U(OH) 3 2.CaCO 3 buildup 3.FePO 4 and water (can get PO 4 from soda) Common Ion Effect and Solubility

18. Solubility 18 pH and Solubility A. Hydroxides – Mg(OH) 2 Milk of Magnesia Mg(OH) 2 (s)  Mg 2+ (aq) + 2OH - (aq) a) Basic solns – LeChatelier (less soluble) b) Acidic solns – More soluble (H + + OH -  H 2 O)

19. Solubility 19 pH and Solubility B.Carbonates – More soluble in acidic solns. CaCO 3 (s) + 2HCl(aq)  H 2 O(l) + CO 2 (g) +CaCl 2 (aq)

20. Solubility 20 1.What is the molar solubility of Ce(OH) 3 (K sp =1.5 X 10 -20 ) in a soln of pH 10.0? (Ans: 1.5 X 10 -8 M) 2. What is the molar solubility of Ce(OH) 3 (K sp =1.5 X 10 -20 ) in a soln of pH 13.0? (Ans: 1.5 X 10 -17 M) pH and Solubility

21. What is the molar solubility of Sn(OH) 2 in a soln of pH 9.2? The Ksp of Sn(OH) 2 is 1.41 x 10 -28. (Ans: 5.6 X 10 -19 M)

22. Solubility 22 Will a ppt form? 1.Q = Reaction Quotient (calculate from Initial concentrations) Q < K sp Shifts to prod (no ppt) Q = K sp Eq. (ppt) Q > K sp Shifts to reac.(ppt) 2. Our Question: Is Q > K sp ?

23. Solubility 23 1.Will a ppt form if a solution is made such that [Ca 2+ ] = 0.0104 M and [SO 4 2- ]=0.0082 M? (Ans: Q = 8.5 X 10 -5, ppt forms) Will a ppt form?

24. Solubility 24 2.Will a ppt form when 100.0 mL of 0.0080 M Pb(NO 3 ) 2 is added to 400.0 mL of 0.0050 M Na 2 SO 4 ? (Ans: Q = 6.4 X 10 -6 so PbSO 4 ppts.) Will a ppt form?

25. Solubility 25 3.Will a ppt form when 50.0 mL of 0.020 M NaF is added to 10.0 mL of 0.010 M Ca(NO 3 ) 2 ? (Ans: Q = 4.6 X 10 -7 so CaF 2 ppts.) Will a ppt form?

26. 26 4.Will a ppt. Form at pH = 8 for a solution of 0.0040 M Mg(NO 3 ) 2 ? 5.At what pH will it form? (9.8) 6.At what pH will a ppt form from a solution of 0.001 M Ni(NO 3 ) 2 ? (ANS: 7.89)

27. Solubility 27 Selective Precipitation 1.You can separate ions based on different solubilities 2.Can be used to remove harmful ions from water.

28. Solubility 28 1.A soln contains 0.01 M Ag + and 0.020 M Pb 2+ ions. If NaCl is slowly added to the soln. which ion will ppt first? (Ans: AgCl will ppt first, [Cl - ] = 1.8 X 10 -8 M) Selective Precipitation

29. Solubility 29 2.A soln contains 0.050 M Mg 2+ and 0.020 M Cu 2+ ions. If KOH is slowly added to the soln. which ion will ppt first? (Ans: Cu(OH) 2 will ppt first, [OH - ] = 1.5 X 10 -9 M) Selective Precipitation

30. 48.a) Solubility is how many grams/100 mL dissolve, K sp is an equilibrium constant. b). K sp = [Mn 2+ ][CO 3 2- ] K sp = [Hg 2+ ][OH - ] 2 K sp = [Cu 2+ ] 3 [PO 4 3- ] 2 50.a) 4 X 10 -6 b) 3.00 X10 -8 c) 2.5 X10 -5 g Cu(OH) 2 52.6.4 X10 -9 30

31. 54.a) 1.82 X10 -3 g/Lb) 4 X10 -11 g/L c) 1 X10 -4 g/L 56. a) 8 X10 -4 Mb) 8 X10 -8 M c) 8 X10 -12 M 64.a) Q = 2 X10 -13 ppt b) Q = 3.3 X10 -5 ppt 68. a) 1.1 X10 -8 vs. 3.2 X10 -5, BaSO 4 first 31

32. Solubility 32

33. Three unlabeled bottles are found. They may contain KNO 3, Ca(NO 3 ) 2 or Cu(NO 3 ) 2. The student labels them A, B and C. After testing the solutions with NaOH and Na 2 SO 4, the following results are tabulated. i.Identify the contents of each bottle. ii.At what pH would a ppt form in solution B if we assume the molarity is about 0.10 M? (4.84) iii.Write the ionic reaction that occurs between solution C and Na 2 SO 4. iv.Calculate the molar solubility of the precipate that solution C forms with Na 2 SO 4. (4.9 X 10 -3 ) 33 ABC NaOHClearCloudyClear Na 2 SO 4 Clear Cloudy