1. 12-1 CHEM 102, Spring 2013 LA TECH Instructor: Dr. Upali Siriwardane e-mail: upali@coes.latech.edu Office: CTH 311 Phone 257-4941 Office Hours: M,W 8:00-9:00 & 11:00-12:00 am; Tu,Th,F 9:30 - 11:30 am. Test Dates : Chemistry 102(01) Spring 2013 September 27, 2013 (Test 1): Chapter 12 & 13 April 24, 2013 (Test 2): Chapter 14 & 15 May13, 2013 (Test 3) Chapter 16 & 17 May 15, 2012 (Make-up test) comprehensive: Chapters 12-17 9:30-10:45:15 AM, CTH 328

2. 12-2 CHEM 102, Spring 2013 LA TECH REQUIRED : Textbook: Principles of Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro - Pearson Prentice Hall and also purchase the Mastering Chemistry Group Homework, Slides and Exam review guides and sample exam questions are available online: http://moodle.latech.edu/ and follow the course information links. http://moodle.latech.edu/ OPTIONAL : Study Guide: Chemistry: A Molecular Approach, 2nd Edition- Nivaldo J. Tro 2nd Edition Student Solutions Manual: Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro 2nd Text Book & Resources

3. 12-3 CHEM 102, Spring 2013 LA TECH Chapter 12. 12. Solutions 12.1 Thirsty Solutions: 12.2 Types of Solutions and Solubility 12.3 Energetics of Solution Formation 12.4 Solubility Equilibrium and Factors Affecting solution Formation 12.5 Expressing Solution Concentration 12.6 Colligative Properties: Vapor Pressure, Freezing Point, Boiling Point, Osmatic Pressure 12.7 Colligative properties of Strong Electrolytes

4. 12-4 CHEM 102, Spring 2013 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)

5. 12-5 CHEM 102, Spring 2013 LA TECH Miscible vs. Immiscible

6. 12-6 CHEM 102, Spring 2013 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

7. 12-7 CHEM 102, Spring 2013 LA TECH Solubility of Ionic Compounds and Temperature

8. 12-8 CHEM 102, Spring 2013 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

9. 12-9 CHEM 102, Spring 2013 LA TECH Types of Solutions (Diluted, Saturated, and Supersaturated)

10. 12-10 CHEM 102, Spring 2013 LA TECH Supersaturated Solution

11. 12-11 CHEM 102, Spring 2013 LA TECH Solute - Solvent Interactions

12. 12-12 CHEM 102, Spring 2013 LA TECH The Solution Making Exopthermic Process

13. 12-13 CHEM 102, Spring 2013 LA TECH The Solution Making Endothermic Process

14. 12-14 CHEM 102, Spring 2013 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,

15. 12-15 CHEM 102, Spring 2013 LA TECH Types of Solute - Solvent Interactions All interactions are electrostatic force ~ Coulombic: proprotional to charge and separation) 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)

16. 12-16 CHEM 102, Spring 2013 LA TECH 1) What are the main factors affecting a solubility of a solute in a solvent?

17. 12-17 CHEM 102, Spring 2013 LA TECH The Solution Making Exopthermic Process

18. 12-18 CHEM 102, Spring 2013 LA TECH The Solution Making Endothermic Process

19. 12-19 CHEM 102, Spring 2013 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

20. 12-20 CHEM 102, Spring 2013 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)

21. 12-21 CHEM 102, Spring 2013 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)

22. 12-22 CHEM 102, Spring 2013 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

23. 12-23 CHEM 102, Spring 2013 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

24. 12-24 CHEM 102, Spring 2013 LA TECH Water Dissolving An Ionic Solute

25. 12-25 CHEM 102, Spring 2013 LA TECH Solution Process of Ionic Compounds

26. 12-26 CHEM 102, Spring 2013 LA TECH Hydration of a Sodium Ion

27. 12-27 CHEM 102, Spring 2013 LA TECH Heats of Solution

28. 12-28 CHEM 102, Spring 2013 LA TECH 5) 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 ?

29. 12-29 CHEM 102, Spring 2013 LA TECH 6) 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. 12-30 CHEM 102, Spring 2013 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. 12-31 CHEM 102, Spring 2013 LA TECH 7) Why sand is insoluble in both polar and nonpolar solvents?

32. 12-32 CHEM 102, Spring 2013 LA TECH 8) 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:

33. 12-33 CHEM 102, Spring 2013 LA TECH Solubility of Oxygen in Water

34. 12-34 CHEM 102, Spring 2013 LA TECH Henry’s Law

35. 12-35 CHEM 102, Spring 2013 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

36. 12-36 CHEM 102, Spring 2013 LA TECH 9) 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.

37. 12-37 CHEM 102, Spring 2013 LA TECH Solution Concentration Units a) Molarity (M) b) Molality (m) c) Mole fraction (a)(a)(a)(a) d) Mass percent (% weight) e) Volume percent (% volume) f) "Proof" g) ppm and ppb

38. 12-38 CHEM 102, Spring 2013 LA TECH Molarity The number of moles of solute per liter of solution. molarity  M moles of solute moles of solute M = liter of solution liter of solution units  molar = moles/liter = M

39. 12-39 CHEM 102, Spring 2013 LA TECH An aqueous solution 58.5 g of NaCl and 2206g water has a density of 1.108 g/cm 3. Calculate the Molarity of the solution. An aqueous solution 58.5 g of NaCl and 2206g water has a density of 1.108 g/cm 3. Calculate the Molarity of the solution. 58.5 g  1 mole 58.5 g  1 mole Solution volume  58.5 g + 2206 g in L 1.00 mole NaCl 1.00 mole NaCl Molarity of NaCl solution = ------------------------- = 0.489 M 2.044 L solution 2.044 L solution 2264.5 g solution1 cm 3 solution1 L solution = 2.044 L solution 1.108 g solution1000 cm 3 solution Molarity Calculation

40. 12-40 CHEM 102, Spring 2013 LA TECH Molality number of moles of solute particles (ions or molecules) per kilogram of solvent #moles solute m = m = #kilograms of solvent #kilograms of solvent Calculate the molality of C 2 H 5 OH in water solution which is prepared by mixing 75.0 mL of C 2 H 5 OH and 125 g of H 2 O at 20 o C. The density of C 2 H 5 OH is 0.789 g/mL.

41. 12-41 CHEM 102, Spring 2013 LA TECH 125 g of H 2 O = 0.125 kg H 2 O 1.284 mole C 2 H 5 OH 1.284 mole C 2 H 5 OH Molality(m) = ------------------------ = 10.27 m 0.125 kg H 2 O 0.125 kg H 2 O 75.0 mL C 2 H 5 OH0.789 g C 2 H 5 OH1 mole C 2 H 5 OH = 1.284 C 2 H 5 OH 1 mL46.08 g C 2 H 5 OH Molarity Calculation

42. 12-42 CHEM 102, Spring 2013 LA TECH Mole Fraction #moles of component i X i = total number of moles Calculate the mole fraction of benzene in a benzene(C 6 H 6 )-chloroform(CHCl 3 ) solution which contains 60 g of benzene and 30 g of chloroform. M.W. = 78.12 (C 6 H 6 ) M.W. = 119.37 (CHCl 3 )

43. 12-43 CHEM 102, Spring 2013 LA TECH moles of a n a moles of a n a Mola Fraction(  a ) = ------------------- = -------------- moles of n a + moles n b n a + n b moles of n a + moles n b n a + n b a = C 6 H 6 a = C 6 H 6 b = CHCl 3 b = CHCl 3 n C6H6 n C6H6 Mola Fraction(  a ) = ------------------ n C6H6 + n CHCl3 n C6H6 + n CHCl3 m.w (C 6 H 6 ) = 78.12 g/mole m.w (CHCl 3 ) = 119.37 g/mole 60/78.12 = 0.768 mole C 6 H 6 30/119.37 = 0.251 mole CHCl 3  a (C 6 H 6 ) = 0.768/ 0.786+ 0.251 =0.754  a ( CHCl 3 ) = 0.0.251/ 0.786+ 0.251 = 0.246 1.000 1.000 Mole Fraction Calculation

44. 12-44 CHEM 102, Spring 2013 LA TECH Weight Percent #g of solute #g of solute wt % =  10 2 wt % =  10 2 #g of solution #g of solution Volume Percent #L of solute Vol % =  10 2 #L of solution Proof proof = Vol % x 2

45. 12-45 CHEM 102, Spring 2013 LA TECH Problem a. 0.40 b. 0.46 c. 0.21 d. 0.54 What is the mole fraction of ethanol, C 2 H 5 OH, in ethanol solution that is 40.%(w/w) ethanol, C 2 H 5 OH, by mass? a. 0.40 b. 0.46 c. 0.21 d. 0.54

46. 12-46 CHEM 102, Spring 2013 LA TECH Parts per Million #g of solute #mg of solute #g of solute #mg of solute ppm =  10 6 = ppm =  10 6 = #g of solution #kg of solution #g of solution #kg of solution #mL solute #mL solute ppm = ppm = #L of solution #L of solution Parts per Billion #g of solute #micro-g of solute ppb =  10 9 = #g of solution #kg of solution

47. 12-47 CHEM 102, Spring 2013 LA TECH ppm and ppb conversions 1 ppm = (1g/ 1x 10 6 g) 1x 10 6 = (1/1000 g) x 1x 10 6 = (1/1000 g) x 1x 10 6 1x 10 6 / 1000g 1x 10 6 / 1000g = mg/ 1x 10 3 g = mg/ 1x 10 3 g = mg/ L = mg/ L 1 ppb = (1g/ 1x 10 9 g) 1x 10 9 = (1/1000000 g) = (1/1000000 g) 1x 10 9 /1000000g 1x 10 9 /1000000g =  g/ 1x 10 3 g =  g/ 1x 10 3 g =  g/ L =  g/ L

48. 12-48 CHEM 102, Spring 2013 LA TECH A solution of hydrogen peroxide is 30.0% H 2 O 2 by mass and has a density of 1.11 g/cm 3. The MOLARITY of the solution is: a)7.94 M b) 8.82 M c) 9.79 M d) 0.980 e) none of these M.W. = 34.02 (H 2 O 2 )Problem

49. 12-49 CHEM 102, Spring 2013 LA TECH 10) Define following solution concentration units: a) Molarity (M) b) Molality (m) c) Mole fraction (  a ) weight) d) Mass percent (% e) Volume percent (% volume) f) "Proof" g) ppm and ppb

50. 12-50 CHEM 102, Spring 2013 LA TECH Comparison of Concentration Terms

51. 12-51 CHEM 102, Spring 2013 LA TECH 11) Compare the advantages and disadvantages of these solution concentration parameters.

52. 12-52 CHEM 102, Spring 2013 LA TECH 12) Determine the number of moles of solute present in 416 mL of 3.75 M HBr solution. (Atomic weights: Br = 79.9, H = 1.008).

53. 12-53 CHEM 102, Spring 2013 LA TECH 13) Determine the mass (g) of solute required to form 25 mL of a 0.1881 M H 2 O 2 solution. (Atomic weight - O = 16.00, H = 1.008).

54. 12-54 CHEM 102, Spring 2013 LA TECH 14) A concentrated solution of AgNO 3 is 21.9% by weight and the density is 1.220 g/cm 3. How many grams of the solution are required to prepare 150.0 mL of a 0.200M solution? (Atomic weights: Ag = 107.87, N = 14.01, O = 16.00).

55. 12-55 CHEM 102, Spring 2013 LA TECH 15) A solution of carbon tetrachloride, CCl 4, in benzene (C 6 H 6 ) is 0.010 m. What mass (g) of CCl 4 is in 50.0 g of benzene? (Atomic weights: C = 12.01, H = 1.008, Cl = 35.45).