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Chemistry 102(01) Spring 2013

Chemistry 102(01) Spring 2013. 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 :. September 27 , 2013 (Test 1): Chapter 12 & 13

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Chemistry 102(01) Spring 2013

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  1. Chemistry 102(01) Spring 2013 Instructor: Dr. UpaliSiriwardane e-mail: upali@coes.latech.edu Office: CTH 311 Phone257-4941 Office Hours: M,W 8:00-9:00 & 11:00-12:00 am; Tu,Th,F9:30 - 11:30 am.  Test Dates: 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. 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. 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. Tro2nd Text Book & Resources

  3. Chapter 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. 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. Miscible vs. Immiscible

  6. “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. Solubility of Ionic Compounds and Temperature

  8. 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. Types of Solutions (Diluted, Saturated, and Supersaturated)

  10. Supersaturated Solution

  11. Solute - Solvent Interactions

  12. The Solution Making Exopthermic Process

  13. The Solution Making Endothermic Process

  14. Thermodynamic Factors Affecting Solubility Energy: Enthalpy (DH) Lowerenergy – DH 2. Order: Entropy (DS) Disorder + DS Exothermic –DH favorssolubility: productfavored Mixing (+DS disorderfavorssolubility:productfavored Gibbs Free Energy: (Chapter 18) DGsoln= DHsoln -TDSsoln,

  15. Types of Solute - Solvent Interactions All interactions are electrostatic force ~ Coulombic: proprotional to charge and separation) London Dispersion Forces: (O2dissolved in Liq. N2) Ion-Ion Interaction: (Ionic liquids in batteries) Ion-Dipole Interaction (hydrated ions Na+(aq)) Dipole-Dipole Interaction (CCl4 in benzene (C6H6) HydrogenBonding. (water and éthanol)

  16. 1) What are the main factors affecting a solubility of a solute in a solvent?

  17. The Solution Making Exopthermic Process

  18. The Solution Making Endothermic Process

  19. 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. 3) Identify the most important type of inter-particle force for each of the following compounds: • NaCl(s) or NaCl(l) b) N2(l) or N2(s) • N2(g) d) Na(s) and Na(l) • e) H2O(l) or H2O(s) f) CH3CH2OH(l) or CH3CH2OH(s)

  21. 4) Which of the above inter-particle force could be named as intermolecular force? • NaCl(s) or NaCl(l) b) N2(l) or N2(s) • N2(g) d) Na(s) and Na(l) • e) H2O(l) or H2O(s) f) CH3CH2OH(l) or CH3CH2OH(s)

  22. Identify Hydrogen Bonding, Polar and Non-polar groups in Covalent Molecules Acetic acid HC2H3O2 CH3COOH Hexanol C6H13OH Propanoic acid C2H5COOH Hexane C6H14 “Like Dissolves Like”

  23. 5) What types of inter-particle forces • solute-solute:DH1, • solvent-solvent: DH2, • solvent-solute:DH3) are involved when • CH3CH2OH(l): dissolved in water,H2O: • DH1= ; DH2= ; DH3= • For covalent compounds: DHsoln= DH1+ DH2+ DH3

  24. Water Dissolving An Ionic Solute

  25. Solution Process of Ionic Compounds

  26. Hydration of a Sodium Ion

  27. Heats of Solution

  28. 5) b)Na2SO4(s)dissolved in water: • DH1 = ; DH2 = ; DH3 = • Ion-ion inter-particle forces in solids are called Lattice Energy. ( this is related to DH1) • Ion-water inter-particle forces are called Hydration Energy (this is related to DH2 and DH3) • For ionic compounds; DHsoln= DHlattice+ DHhyd • Qualitatively speaking which of the above a) or b) would have a more exothermic DHsoln?

  29. 6) Assign the entropy (most +, medium + or least +) for i) S1 –solute: ii) S2-solvent: iii) S3, solution (solvent-solute): • For the following: (Indicate which one is highest, intermediate and lowest order) For • a) CH3CH2OH(l): dissolved in water: • S1 = ; S2 = ;S3= • Na2SO4(s)dissolved in water: • S1 = ; S2 = ;S3 =

  30. 5) Qualitatively speaking which of the above a) or b) would have a more positive DSsoln? • a) CH3CH2OH(l): dissolved in water: • S1 = ; S2 = ;S3= • For Na2SO4(s)dissolved in water: • S1 = ; S2 = ;S3 =

  31. 7) Why sand is insoluble in both polar and nonpolar solvents?

  32. 8) How does temperature and pressure affect the solubility of following? • NH4NO3(solid) in water with +(positive) DHsoln: • CO2 gas in water:

  33. Solubility of Oxygen in Water

  34. Henry’s Law

  35. Henry’s LawSolubility of Gases in Solvents Sg = kHPg where Sg solubility kH Henry’s Law constant Pg partial pressure of gas Increasingthe pressure of a gas above a liquid increases its solubility

  36. 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. Solution Concentration Units a) Molarity (M) b) Molality (m) c) Mole fraction (Ca) d) Mass percent (% weight) e) Volume percent (% volume) f) "Proof" g) ppm and ppb

  38. Molarity The number of moles of solute per liter of solution. molarity M moles of solute M = liter of solution units  molar = moles/liter = M

  39. Molarity Calculation An aqueous solution 58.5 g of NaCl and 2206g water has a density of 1.108 g/cm3. Calculate the Molarity of the solution. 58.5 g  1 mole Solution volume 58.5 g + 2206 g in L                                         1.00 mole NaCl Molarity of NaCl solution = ------------------------- = 0.489 M                                                    2.044 L solution

  40. Molality • number of moles of solute particles (ions or molecules) per kilogram of solvent #moles solute m = #kilograms of solvent Calculate the molality of C2H5OH in water solution which is prepared by mixing 75.0 mL of C2H5OH and 125 g of H2O at 20oC. The density of C2H5OH is 0.789 g/mL.

  41. Molarity Calculation 125 g of H2O = 0.125 kg H2O                       1.284 mole C2H5OH Molality(m) = ------------------------ = 10.27 m                          0.125 kg H2O

  42. Mole Fraction #moles of component i Xi = total number of moles Calculate the mole fraction of benzene in a benzene(C6H6)-chloroform(CHCl3) solution which contains 60 g of benzene and 30 g of chloroform.M.W. = 78.12 (C6H6) M.W. = 119.37 (CHCl3)

  43. Mole Fraction Calculation                                  moles of a                na Mola Fraction(ca) = -------------------  =     --------------                             moles of na + moles nbna + nb             a = C6H6             b = CHCl3                                      nC6H6 Mola Fraction(ca) = ------------------                                    nC6H6 + nCHCl3 m.w (C6H6) = 78.12 g/mole m.w (CHCl3) = 119.37 g/mole 60/78.12 = 0.768 mole C6H6 30/119.37 = 0.251 mole CHCl3 ca(C6H6) = 0.768/ 0.786+ 0.251 =0.754 Ca(CHCl3) = 0.0.251/ 0.786+ 0.251 = 0.246 1.000

  44. Weight Percent #g of solute wt % =  102 #g of solution Volume Percent #L of solute Vol % = 102 #L of solution Proof proof = Vol % x 2

  45. Problem What is the mole fraction of ethanol, C2H5OH, in ethanol solution that is 40.%(w/w) ethanol, C2H5OH, by mass?a. 0.40 b. 0.46 c. 0.21 d. 0.54

  46. Parts per Million #g of solute #mg of solute ppm =  106 = #g of solution #kg of solution #mL solute ppm = #L of solution Parts per Billion #g of solute #micro-g of solute ppb =  109 = #g of solution #kg of solution

  47. ppm and ppb conversions 1 ppm = (1g/ 1x 106g) 1x 106 = (1/1000 g) x 1x 106 1x 106 / 1000g = mg/ 1x 103 g = mg/ L 1 ppb = (1g/ 1x 109g) 1x 109 = (1/1000000 g) 1x 109/1000000g = mg/ 1x 103 g = mg/ L

  48. Problem A solution of hydrogen peroxide is 30.0% H2O2 by mass and has a density of 1.11 g/cm3. The MOLARITY of the solution is: 7.94 M b) 8.82 M c) 9.79 M d) 0.980 e) none of theseM.W. = 34.02 (H2O2)

  49. 10) Define following solution concentration units: • a) Molarity (M) b) Molality (m) • c) Mole fraction (Ca) weight) • d) Mass percent (% • e) Volume percent (% volume) • f) "Proof" • g) ppm and ppb

  50. Comparison of Concentration Terms

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