1. Philip Dutton University of Windsor, Canada N9B 3P4 Prentice-Hall © 2008 General Chemistry Principles and Modern Applications Petrucci Harwood Herring 8 th Edition Chapter 13: Solutions and Their Physical Properties

2. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 2 of 46 Contents 13-1Types of Solutions: Some Terminology 13-2Solution Concentration 13-3Intermolecular Forces and the Solution Process 13-4Solution Formation and Equilibrium 13-5Solubilities of Gases 13-6Vapor Pressure of Solutions 13-7Osmotic Pressure

3. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 3 of 46 Contents 13-8Freezing-Point Depression and Boiling-Point Elevation of Nonelectrolyte solutions. 13-9Solutions of Electrolytes 13-10Colloidal Mixtures Focus on Chromatography

4. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 4 of 46 13-1 Types of Solution: Some Terminology Solutions are homogeneous mixtures. –Uniform throughout. Solvent. –Determines the state of matter in which the solution exists. –Is the largest component. Solute. –Other solution components said to be dissolved in the solution.

5. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 5 of 46 Table 14.1 Some Common Solutions

6. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 6 of 46 13-2 Solution Concentration. Mass percent. (m/m) Volume percent. (v/v) Mass/volume percent. (m/v) Isotonic saline is prepared by dissolving 0.9 g of NaCl in 100 mL of water and is said to be: 0.9% NaCl (mass/volume)

7. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 7 of 46 10% Ethanol Solution (v/v)

8. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 8 of 46 ppm, ppb and ppt Very low solute concentrations are expressed as: ppm:parts per million (  g/g, mg/L) ppb:parts per billion(ng/g,  g/L) ppt:parts per trillion(pg/g, ng/L) note that 1.0 L · 1.0 g/mL = 1000 g ppm, ppb, and ppt are properly m/m or v/v.

9. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 9 of 46 Mole Fraction and Mole Percent  = Amount of component i (in moles) Total amount of all components (in moles)  1 +  2 +  3 + …  n = 1 Mole % i =  i · 100%

10. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 10 of 46 Molarity and Molality Molarity (M) = Amount of solute (in moles) Volume of solution (in liters) Molality (m) = Amount of solute (in moles) Mass of solvent (in kilograms)

11. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 11 of 46 13-3 Intermolecular Forces and the Solution Process ΔHaΔHa ΔHbΔHb ΔHcΔHc

12. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 12 of 46 Intermolecular Forces in Mixtures Magnitude of ΔH a, ΔH b, and ΔH c depend on intermolecular forces. Ideal solution –Forces are similar between all combinations of components. ΔH soln = 0

13. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 13 of 46 Ideal Solution

14. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 14 of 46 Non-ideal Solutions Adhesive forces greater than cohesive forces. ΔH soln < 0

15. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 15 of 46 Non-ideal Solutions Adhesive forces are less than cohesive forces. At the limit these solutions are heterogeneous. ΔH soln > 0

16. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 16 of 46 Ionic Solutions

17. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 17 of 46 Hydration Energy NaCl(s) → Na + (g) + Cl - (g)ΔH lattice > 0 Na + (g) + xs H 2 O(l) → Na + (aq)ΔH hydration < 0 Cl - (g) + xs H 2 O(l) → Cl - (aq)ΔH hydration < 0 ΔH soln > 0 but ΔG solution < 0

18. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 18 of 46 13-4 Solution Formation and Equilibrium saturated

19. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 19 of 46 Solubility Curves Supersaturated Unsaturated

20. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 20 of 46 13-5 Solubility of Gases Most gases are less soluble in water as temperature increases. In organic solvents the reverse is often true.

21. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 21 of 46 Henry’s Law Solubility of a gas increases with increasing pressure. C = k P gas k = C P gas = 23.54 mL 1.00 atm = 23.54 ml N 2 /atm k C P gas = = 100 mL = 4.25 atm 23.54 ml N 2 /atm

22. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 22 of 46 Henry’s Law

23. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 23 of 46 13-6 Vapor Pressures of Ideal Solutions Roault, 1880s. –Dissolved solute lowers vapor pressure of solvent. –The partial pressure exerted by solvent vapor above an ideal solution is the product of the mole fraction of solvent in the solution and the vapor pressure of the pure solvent at a given temperature. P A =  A P° A ΔH mix = 0 ΔV mix = 0

24. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 24 of 46 Example 13-6 Predicting vapor pressure of ideal solutions. The vapor pressures of pure benzene and toluene at 25°C are 95.1 and 28.4 mm Hg, respectively. A solution is prepared in which the mole fractions of benzene and toluene are both 0.500. What are the partial pressures of the benzene and toluene above this solution? What is the total vapor pressure? P benzene =  benzene P° benzene = 0.500 · (95.1 mm Hg) = 47.6 mm Hg P toluene =  toluene P° toluene = 0.500 · (28.4 mm Hg) = 14.2 mm Hg P total = P benzene + P toluene = 61.8 mm Hg

25. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 25 of 46 Example 13-7 Calculating the Composition of Vapor in Equilibrium with a Liquid Solution. What is the composition of the vapor in equilibrium with the benzene-toluene solution? Partial pressure and mole fraction: y benzene = P benzene /P total = 47.6 mm Hg/61.89 mm Hg = 0.770 y toluene = P toluene /P total = 14.2 mm Hg/61.89 mm Hg = 0.230

26. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 26 of 46 Liquid-Vapor Equilibrium Benzene Toluene Mixture T = const.

27. Benzene Toluene mixture x-y diagram Prentice-Hall © 2008General Chemistry: Chapter 14Slide 27 of 46 T=298 K

28. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 28 of 46 Fractional Distillation P = const.

29. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 29 of 46 Fractional Distillation

30. Non ideal solution (T= 298 K) Csonka Gábor © 2008Általános Kémia: oldatok 30 dia Ideal solution: Solvent – Raoult law, Solute – Henry’s law Chloroform –acetone Non ideal solution Negative deviation from the Roault law: Stronger adhesion than cohesion Lower vapor pressure Higher boiling point

31. Non ideal solution (T= 298 K) Csonka Gábor © 2008Általános Kémia: oldatok 31 dia Positive deviation from the ideal solution Higher vapor pressure Lower boiling point Acetone CS 2

32. Positive and Negative Azeotropes (T=const.) Csonka Gábor © 2008General Chemistry: solutiomns 32 dia

33. Azeotrope Csonka Gábor © 2008Általános Kémia: oldatok 33 dia An azeotrope is a mixture of two or more pure compounds in such a ratio that its composition cannot be changed by simple distillation. When an azeotrope is boiled, the resulting vapor has the same ratio of constituents as the original mixture of liquids.

34. Positive azeotrope (p = const.) Csonka Gábor © 2008General Chemistry: solutions 34 dia P = 101.3 kPa 95.6% ethanol (78.4°C) 4.4% water (100°C) Boiling point78.1°C Minimal boiling point

35. General Chemistry: Chapter 14Slide 35 of 46 Non-ideal behavior Positive azeotrope

36. Positive Azeotrope - Mixture of Chloroform and Methanol WikiGeneral Chemistry: Chapter 14Slide 36 of 46

37. Negative azeotrope (P = const.) Csonka Gábor © 2008Általános Kémia: oldatok 37 dia P =101.3 kPa 20.2% HCl (-84°C) 79.8% víz (100°C) Boiling point: 110°C Maximal bp. HF (35.6%): 111.4°C HNO 3 (68%): 120.5°C HClO 4 (28.4%): 203°C H 2 SO 4 (98.3%): 338°C

38. Negative Azeotrope - Mixture of Formic acid and Water WikiÁltalános Kémia: oldatok 38 dia

39. Eutectic mixture Csonka Gábor © 2008Általános Kémia: oldatok 39 dia Water + NaCl Eutectic temperature: -21.2 °C at 23.3% Alloys Inkjet printers Solid – liquid equilibrium A eutectic or eutectic mixture is a mixture at such proportions that the melting point (temperature of solidification) is as low as possible.

40. Fe-C eutectic Csonka Gábor © 2008Általános Kémia: oldatok 40 dia

41. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 41 of 46 13-7 Osmotic Pressure Ozmosis: the solvent moves freely the solute does not. π =  g  h π = RT n V

42. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 42 of 46 Osmotic Pressure πV = nRT π = RT n V = M RT For dilute solutions of electrolytes:

43. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 43 of 46 Osmotic Pressure Isotonic Saline 0.92% m/V Hypertonic > 0.92% m/V crenation Hypotonic < 0.92% m/V rupture

44. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 44 of 46 Reverse Osmosis - Desalination

45. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 45 of 46 13-8 Freezing-Point Depression and Boiling Point Elevation of Nonelectrolyte Solutions Vapor pressure is lowered when a solute is present. –This results in boiling point elevation. –Freezing point is also effected and is lowered. Colligative properties. –Depends on the number of particles present.

46. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 46 of 46 Vapor Pressure Lowering ΔT f = -K f · m ΔT b = K b · m

47. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 47 of 46 Practical Applications

48. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 48 of 46 13-9 Solutions of Electrolytes Svante Arrhenius –Nobel Prize 1903: „..by his electrolytic theory of dissociation” –Ions form when electrolytes dissolve in solution. –Explained anomalous colligative properties ΔT f = -K f · m = -1.86°C m -1 · 0.0100 m = -0.0186°C Compare 0.0100 m aqueous urea to 0.0100 m NaCl (aq) Freezing point depression for NaCl is -0.0361°C.

49. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 49 of 46 van’t Hoff ΔT f = -i · K f · m i = == 1.98 measured ΔT f ΔT b = i · K b · m expected ΔT f 0.0361°C 0.0186°C π = i · M · RT

50. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 50 of 46 Interionic Interactions Arrhenius theory does not correctly predict the conductivity of concentrated electrolytes.

51. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 51 of 46 Debye and Hückel 1923 –Ions in solution do not behave independently. –Each ion is surrounded by others of opposite charge. –Ion mobility is reduced by the drag of the ionic atmosphere.

52. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 52 of 46 13-10 Colloidal Mixtures

53. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 53 of 46 Colloids Particles of 1-1000 nm size. –Nanoparticles of various shapes: rods, discs, spheres. –Particles can remain suspended indefinitly. Milk is colloidal. Increasing ionic strength can cause precipitation.

54. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 54 of 46 Dialysis

55. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 55 of 46 Focus on Chromatography Stationary Phase silicon gum alumina silica Mobile Phase solvent gas

56. Prentice-Hall © 2008General Chemistry: Chapter 14Slide 56 of 46 Chromatography