1. 15-1 CHEM 102, Spring 2012 LA TECH CTH 328 9:30-10:45 am Instructor: Dr. Upali Siriwardane e-mail: upali@latech.edu Office: CTH 311 Phone 257-4941 Office Hours: M,W 8:00-9:00 & 11:00-12:00 am; Tu,Th,F 8:00 - 10:00 am.. Exams: 9:30-10:45 am, CTH 328. March 26, 2012 (Test 1): Chapter 13 April 18, 2012 (Test 2): Chapter 14 &15 May 14, 2012 (Test 3): Chapter 16 &18 Optional Comprehensive Final Exam: May 17, 2012 : Chapters 13, 14, 15, 16, 17, and 18 Chemistry 102(01) Spring 2012

2. 15-2 CHEM 102, Spring 2012 LA TECH Chapter 15. The Chemistry of Solutes and Solutions 15.1Solubility and Intermolecular Forces 15.2Enthalpy, Entropy, and Dissolving Solids 15.3Solubility and Equilibrium 15.4Temperature and Solubility 15.5Pressure and Dissolving Gases in Liquids: Henry's Law Law 15.6Solution Concentration: Keeping Track of Units 15.7 Vapor Pressures, Boiling Points, and Freezing Points of Solutions 15.8 Osmotic Pressure of Solutions 15.9 Colloids 15.10 Surfactants 15.11 Water: Natural, Clean, and Otherwise

3. 15-3 CHEM 102, Spring 2012 LA TECH Solution Terminology Solute one or more substance(s) dispersed in the solution Solvent majority substance in a solution The solubility of a solid in a solvent is typically given in g/100 ml. Types of solutions Mixture of Gases Liquid solutions (L+S,L+L,L+G) Solid solutions (S+S, alloys) Aerosols (L+G) Foam (S+G)

4. 15-4 CHEM 102, Spring 2012 LA TECH Miscible vs. Immiscible

5. 15-5 CHEM 102, Spring 2012 LA TECH “Likes Dissolve Likes” Materials with similar polarity are soluble in each other. Dissimilar ones are not. Polar substances with similar forces are likely to be soluble in each other Non-polar solutes dissolve in non-polar solvents stronger solute-solvent attractions favor solubility, stronger solute-solute or solvent- solvent attractions reduce solubility

6. 15-6 CHEM 102, Spring 2012 LA TECH Solubility of Ionic Compounds and Temperature

7. 15-7 CHEM 102, Spring 2012 LA TECH Solution Terminology Miscible - liquids that dissolve in each other Immiscible - liquids that do not dissolve in each other due to differences types of interactions Saturated solution A solution that contains as much it can hold Unsaturated solution A solution that contains less than maximum amount Supersaturated solution A solution that contains more than maximum amount

8. 15-8 CHEM 102, Spring 2012 LA TECH Types of Solutions (Diluted, Saturated, and Supersaturated)

9. 15-9 CHEM 102, Spring 2012 LA TECH Supersaturated Solution

10. 15-10 CHEM 102, Spring 2012 LA TECH Solute - Solvent Interactions

11. 15-11 CHEM 102, Spring 2012 LA TECH The Solution Making Exopthermic Process

12. 15-12 CHEM 102, Spring 2012 LA TECH The Solution Making Endothermic Process

13. 15-13 CHEM 102, Spring 2012 LA TECH Thermodynamic Factors Affecting Solubility 1.Energy: Enthalpy (  H) Lower energy –  H 2. Order: Entropy (  S) Disorder +  S Exothermic –  H favors solubility: product favored Mixing (+  S disorder favors solubility: product favored Gibbs Free Energy: (Chapter 18)  G soln =  H soln -T  S soln,

14. 15-14 CHEM 102, Spring 2012 LA TECH Types of Solute - Solvent Interactions All interactions are electrostatic force ~ Coulombic: proprotional to charge and séparation) 1.London Dispersion Forces: (O 2 dissolved in Liq. N 2 ) 2.Ion-Ion Interaction: (Ionic liquids in batteries) 3.Ion-Dipole Interaction (hydrated ions Na + (aq)) 4.Dipole-Dipole Interaction (CCl 4 in benzene (C 6 H 6 ) 5.Hydrogen Bonding. (water and éthanol)

15. 15-15 CHEM 102, Spring 2012 LA TECH 1) What are the main factors affecting a solubility of a solute in a solvent?

16. 15-16 CHEM 102, Spring 2012 LA TECH The Solution Making Exopthermic Process

17. 15-17 CHEM 102, Spring 2012 LA TECH The Solution Making Endothermic Process

18. 15-18 CHEM 102, Spring 2012 LA TECH 2) Arrange the following inter-particles forces in liquids and solids in the order of increasing strength: ion-ion, ion-dipole, hydrogen bond, dipole-dipole and London dispersion

19. 15-19 CHEM 102, Spring 2012 LA TECH 3) Identify the most important type of inter-particle force for each of the following compounds: a) a) NaCl(s) or NaCl(l) b) N 2 (l) or N 2 (s) c) c) N 2 (g) d) Na(s) and Na(l) e) H 2 O(l) or H 2 O(s) f) CH 3 CH 2 OH(l) or CH 3 CH 2 OH(s)

20. 15-20 CHEM 102, Spring 2012 LA TECH 4) Which of the above inter-particle force could be named as intermolecular force? a) a) NaCl(s) or NaCl(l) b) N 2 (l) or N 2 (s) c) c) N 2 (g) d) Na(s) and Na(l) e) H 2 O(l) or H 2 O(s) f) CH 3 CH 2 OH(l) or CH 3 CH 2 OH(s)

21. 15-21 CHEM 102, Spring 2012 LA TECH Acetic acid HC 2 H 3 O 2 CH 3 COOH Hexanol C 6 H 13 OH Hexane C 6 H 14 Propanoic acid C 2 H 5 COOH “Like Dissolves Like” Identify Hydrogen Bonding, Polar and Non-polar groups in Covalent Molecules

22. 15-22 CHEM 102, Spring 2012 LA TECH 5) What types of inter-particle forces solute-solute:  H 1, solvent-solvent:  H 2, solvent-solute:  H 3 ) are involved when a) a) CH 3 CH 2 OH(l): dissolved in water,H 2 O:  H 1 = ;  H 2 = ;  H 3 = For covalent compounds:  H soln =  H 1 +  H 2 +  H 3

23. 15-23 CHEM 102, Spring 2012 LA TECH Water Dissolving An Ionic Solute

24. 15-24 CHEM 102, Spring 2012 LA TECH Solution Process of Ionic Compounds

25. 15-25 CHEM 102, Spring 2012 LA TECH Hydration of a Sodium Ion

26. 15-26 CHEM 102, Spring 2012 LA TECH Heats of Solution

27. 15-27 CHEM 102, Spring 2012 LA TECH 4) b) Na 2 SO 4 (s) dissolved in water:  H 1 = ;  H 2 = ;  H 3 = Ion-ion inter-particle forces in solids are called Lattice Energy. ( this is related to  H 1 ) Ion-water inter-particle forces are called Hydration Energy (this is related to  H 2 and  H 3 ) For ionic compounds;  Hs oln =  H lattice +  H hyd Qualitatively speaking which of the above a) or b) would have a more exothermic  H soln ?

28. 15-28 CHEM 102, Spring 2012 LA TECH 4) What factors make it more exothermic? a) a) CH 3 CH 2 OH in H 2 O  H 1 = ;  H 2 = ;  H 3 = b) b) Na 2 SO 4 (s) dissolved in water: (  H 1 =  Hs oln )+ (H hyd =  H 2 +  H 3 )

29. 15-29 CHEM 102, Spring 2012 LA TECH 5) Assign the entropy (most +, medium + or least +) for i) S 1 –solute: ii) S 2 -solvent: iii) S 3, solution (solvent-solute): For the following: (Indicate which one is highest, intermediate and lowest order) For a) CH 3 CH 2 OH(l): dissolved in water: S 1 = ; S 2 = ;S 3 = Na 2 SO 4 (s) dissolved in water: S1 = ; S2 = ;S3 =

30. 15-30 CHEM 102, Spring 2012 LA TECH 5) Qualitatively speaking which of the above a) or b) would have a more positive  S soln ? a) CH 3 CH 2 OH(l): dissolved in water: S 1 = ; S 2 = ;S 3 = b) b) For Na 2 SO 4 (s) dissolved in water: S 1 = ; S 2 = ;S 3 =

31. 15-31 CHEM 102, Spring 2012 LA TECH 6) Calculate the  Hsoln for dissolving CaCl 2 (s) in water given the Lattice-Energy CaCl 2 (s) = +2258 kJ/mole), and Hydration energy for CaCl 2 = - 2205 kJ/mole (  Hs oln =  H lattice +  H hyd =?)

32. 15-32 CHEM 102, Spring 2012 LA TECH 7)  H soln value thermodynamically product favored?

33. 15-33 CHEM 102, Spring 2012 LA TECH 8) For dissolving CaCl 2 (s) in water, which of the following entropy represent the highest order? Explain. a)S for CaCl 2 (s): +104.6 J/mole b) S for H 2 O(l): +69.91 J/mole c) S for solution CaCl 2 (aq): +815 J/mole

34. 15-34 CHEM 102, Spring 2012 LA TECH 9) Calculate the  S soln for dissolving CaCl 2 (s) in water given the entropies of Lattice- CaCl 2 (s) (S 1 = +104.6 J/mole), H 2 O(l)(S 2 = +69.91 J/mole); CaCl 2 (aq)(S 3 = +815 J/mole).  S soln = S final -S initial =S 3 - ( S 1 + S 2 )?

35. 15-35 CHEM 102, Spring 2012 LA TECH 10) Calculate the  S soln for dissolving CaCl 2 (s) in water given the entropies of Lattice- CaCl 2 (s) (S 1 = +104.6 J/mole), H 2 O(l)(S 2 = +69.91 J/mole); CaCl 2 (aq)(S 3 = +815 J/mole).  S soln = S final -S initial =S 3 - ( S 1 + S 2 )?

36. 15-36 CHEM 102, Spring 2012 LA TECH 11)  S soln value thermodynamically product favored?

37. 15-37 CHEM 102, Spring 2012 LA TECH 12) Based on  Gsoln, determine if CaCl 2 is soluble at 25  C, given,  G soln =  H soln -T  S soln, and  H soln and  S soln calculated above.

38. 15-38 CHEM 102, Spring 2012 LA TECH 13) Why sand is insoluble in both polar and nonpolar solvents?

39. 15-39 CHEM 102, Spring 2012 LA TECH 14) How does temperature and pressure affect the solubility of following? a) a) NH 4 NO 3 (solid) in water with +(positive)  H soln : b) b) CO 2 gas in water:

40. 15-40 CHEM 102, Spring 2012 LA TECH Solubility of Oxygen in Water

41. 15-41 CHEM 102, Spring 2012 LA TECH Henry’s Law

42. 15-42 CHEM 102, Spring 2012 LA TECH Henry’s Law Solubility of Gases in Solvents S g = k H P g where S g  solubility k H  Henry’s Law constant P g  partial pressure of gas Increasing the pressure of a gas above a liquid increases its solubility

43. 15-43 CHEM 102, Spring 2012 LA TECH 15) Deep sea divers may experience a condition called the "bends" if they do not readjust slowly to the lower pressure at the surface. Using the diagram on pressure dependence solubility of gases on water explain this phenomenon.