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- ]

Solubility 2

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

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

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

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

8 6.The solubility of Fe(OH) 3 is g/L. a. Calculate the molar solubility (7.4 X M) b. Calculate K sp ? (Ans: 8.1 X ) c. Calculate how many grams will dissolve in 250 mL ( 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 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 ) 8. What is the solubility in g/100 mL of CaSO 4 if the K sp is 2.4 X ? (Ans: g/100 mL) 9.What is the solubility of CaF 2 in g/100 mL if the K sp is 3.9 X ? (Ans: g/100mL)

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

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

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

Solubility 13 Common Ion Effect and Solubility

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

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

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

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

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)

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)

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

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 (Ans: 5.6 X M)

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 ?

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

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

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

26 4.Will a ppt. Form at pH = 8 for a solution of 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 M Ni(NO 3 ) 2 ? (ANS: 7.89)

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

Solubility 28 1.A soln contains 0.01 M Ag + and 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 M) Selective Precipitation

Solubility 29 2.A soln contains M Mg 2+ and 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 M) Selective Precipitation

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 b) 3.00 X10 -8 c) 2.5 X10 -5 g Cu(OH) X

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

Solubility 32

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 ) 33 ABC NaOHClearCloudyClear Na 2 SO 4 Clear Cloudy