Chapter 13 Intermolecular Forces, Liquids, and Solids

1. Chapter 13Intermolecular Forces, Liquids, and Solids

2. Which of the following molecules can hydrogen bond with itself? • 1, 2 • 2, 3 • 3, 4 • 1, 2, 3 • 1, 2, 3, 4

3. Which of the following molecules can hydrogen bond with itself? • 1, 2 • 2, 3 • 3, 4 • 1, 2, 3 • 1, 2, 3, 4

4. Arrange the following according to increasing melting point. Kr I2 O2 He • O2 < He < I2 < Kr • He < O2 < I2 < Kr • He < O2 < Kr < I2 • I2 < Kr < O2 < He • I2 < Kr < He < O2

5. Arrange the following according to increasing melting point. Kr I2 O2 He • O2 < He < I2 < Kr • He < O2 < I2 < Kr • He < O2 < Kr < I2 • I2 < Kr < O2 < He • I2 < Kr < He < O2

6. Arrange the following according to increasing melting point. MgO CO2 O2 H2O • MgO < H2O < CO2 < O2 • O2 < CO2 < H2O < MgO • O2 < H2O < CO2 < MgO • H2O < O2 < MgO < CO2 • O2 < CO2 < H2O < MgO

7. Arrange the following according to increasing melting point. MgO CO2 O2 H2O • MgO < H2O < CO2 < O2 • O2 < CO2 < H2O < MgO • O2 < H2O < CO2 < MgO • H2O < O2 < MgO < CO2 • O2 < CO2 < H2O < MgO

8. Arrange the following according to increasing vapor pressure. NH3 I2 Br2 CH4 • NH3 < I2 < Br2 < CH4 • I2 < Br2 < NH3 < CH4 • NH3 < CH4 < I2 < Br2 • NH3 < I2 < CH4 < Br2 • CH4 < NH3 < Br2 < I2

9. Arrange the following according to increasing vapor pressure. NH3 I2 Br2 CH4 • NH3 < I2 < Br2 < CH4 • I2 < Br2 < NH3 < CH4 • NH3 < CH4 < I2 < Br2 • NH3 < I2 < CH4 < Br2 • CH4 < NH3 < Br2 < I2

10. Which does not represent close packing? • ABABAB • ABCABC • ABACBAC • AABCABB • CACBABC

11. Which does not represent close packing? • ABABAB • ABCABC • ABACBAC • AABCABB • CACBABC

12. 800 600 Vapor Pressure (mm Hg) 400 200 0 0 25 50 75 100 Temperature ( ° C) Which statement is true? • Boiling point ~120°C • Boiling point ~95°C • Boiling point ~75°C • Melting point ~95°C • Melting point ~75°C

13. 800 600 Vapor Pressure (mm Hg) 400 200 0 0 25 50 75 100 Temperature ( ° C) Which statement is true? • Boiling point ~120°C • Boiling point ~95°C • Boiling point ~75°C • Melting point ~95°C • Melting point ~75°C

14. Lead crystallizes in a face-centered cubic unit cell. How many lead atoms are in one unit cell? • 1 • 2 • 4 • 10 • 14

15. Lead crystallizes in a face-centered cubic unit cell. How many lead atoms are in one unit cell? • 1 • 2 • 4 • 10 • 14

16. How many tetrahedral holes are in a face- centered cubic unit cell? • 2 • 4 • 6 • 8 • 14

17. How many tetrahedral holes are in a face- centered cubic unit cell? • 2 • 4 • 6 • 8 • 14

18. Of the following substances, predict which has the highest boiling point based on intermolecular forces. Propane, C3H8 Dimethyl ether, CH3OCH3 Methyl chloride, CH3Cl Acetaldehyde, CH3CHO Acetonitrile, CH3CN

19. Of the following substances, predict which has the highest boiling point based on intermolecular forces. Propane, C3H8 Dimethyl ether, CH3OCH3 Methyl chloride, CH3Cl Acetaldehyde, CH3CHO Acetonitrile, CH3CN

20. Correct Answer: Propane, C3H8 Dimethyl ether, CH3OCH3 Methyl chloride, CH3Cl Acetaldehyde, CH3CHO Acetonitrile, CH3CN Each of these molecules has almost the same molecular weight; however, acetonitrile has the largest dipole moment (3.9 D) and hence the largest dipole-dipole forces. Thus it has the highest boiling point.

21. Of the following substances, predict which has the lowest boiling point based on London dispersion forces. • He • Ne • Ar • Kr • Xe

22. Correct Answer: • He • Ne • Ar • Kr • Xe More massive species have more polarizability and stronger London dispersion forces; consequently, amongst the noble gases He has the lowest boiling point.

23. Of the following substances, predict which has the highest boiling point based upon intermolecular forces? CH4 H2O H2S SiH4 H2Se NH …….O=C

24. Correct Answer: CH4 H2O H2S SiH4 H2Se Of these, only H2O has any hydrogen bonding. Hydrogen bonding substantially increases the intermolecular forces, and hence the boiling point.

25. Which one of the following phase changes is an exothermic process? Sublimation Vaporization Condensation Melting

26. Correct Answer: Sublimation Vaporization Condensation Melting All the other phase-change processes listed are endothermic.

27. How much energy is required to raise the temperature of 1800. g ice at 0°C to 10°C? DHfus = 6.01 kJ/mol, heat capacity of water is 75.2 J/mol-K. 60.1 kJ 75.2 kJ 135 kJ 601 kJ 676 kJ

28. Correct Answer: There are 100 moles of ice, so the enthalpy of fusion is: DH =(6.01 kJ/mol)(100 mol) = 601 kJ. To raise the water temperature 10°C requires q = (75.2 J/mol-K)(100 mol)(10°C ) = 75.2 kJ. Total energy = 601 kJ +75 kJ = 676 kJ 60.1 kJ 75.2 kJ 135 kJ 601 kJ 676 kJ

29. D B Pressure A C Temperature In the unlabeled phase diagram below, the line segment from A to B separates which two phases? Gas-liquid Liquid-solid Solid-gas

30. D B Pressure A C Temperature Correct Answer: Gas-liquid Liquid-solid Solid-gas

31. Quartz is an example of which type of solid: crystalline or amorphous? Crystalline Amorphous

32. Correct Answer: In quartz, the SiO bonds are arranged in regular, defined arrays. Crystalline Amorphous

33. What are the net number of Na+ and Cl ions in the NaCl unit cell represented below? 4 Na+, 4 Cl 2 Na+, 1 Cl 2 Na+, 2 Cl 1 Na+, 2 Cl 1 Na+, 1 Cl

34. Correct Answer: There are 4 Na+ resulting from: (1/4 Na+/edge)(12 edges) = 3 Na+ (1 Na+/center)(1 center) = 1 Na+ There are 4 Cl− resulting from: (1/8 Cl/corner)(8 corners) = 1 Cl (1/2 Cl/face)(6 faces) = 3 Cl 4 Na+, 4 Cl 2 Na+, 1 Cl 2 Na+, 2 Cl 1 Na+, 2 Cl 1 Na+, 1 Cl

35. The NaCl crystal shown below is an example of which type of cubic lattice? Primitive cubic Body-centered cubic Face-centered cubic

36. Correct Answer: Primitive cubic Body-centered cubic Face-centered cubic NaCl is an example of a face-centered crystalline lattice.

37. Diamond and graphite are examples of which type of crystalline solids? Molecular Covalent network Ionic Metallic

38. Correct Answer: Molecular Covalent network Ionic Metallic Diamond and graphite are both forms of carbon, and consist of a network of covalent bonds (hence covalent network).

39. Correct Answer: Propane, C3H8 Dimethyl ether, CH3OCH3 Methyl chloride, CH3Cl Acetaldehyde, CH3CHO Acetonitrile, CH3CN Each of these molecules has almost the same molecular weight; however, acetonitrile has the largest dipole moment (3.9 D) and hence the largest dipole-dipole forces. Thus it has the highest boiling point.

40. Of the following substances, predict which has the lowest boiling point based on London dispersion forces. • He • Ne • Ar • Kr • Xe

41. Correct Answer: • He • Ne • Ar • Kr • Xe More massive species have more polarizability and stronger London dispersion forces; consequently, amongst the noble gases He has the lowest boiling point.

42. Of the following substances, predict which has the highest boiling point based upon intermolecular forces? CH4 H2O H2S SiH4 H2Se NH …….O=C

43. Correct Answer: CH4 H2O H2S SiH4 H2Se Of these, only H2O has any hydrogen bonding. Hydrogen bonding substantially increases the intermolecular forces, and hence the boiling point.

44. Which one of the following phase changes is an exothermic process? Sublimation Vaporization Condensation Melting

45. Correct Answer: Sublimation Vaporization Condensation Melting All the other phase-change processes listed are endothermic.

46. How much energy is required to raise the temperature of 1800. g ice at 0°C to 10°C? DHfus = 6.01 kJ/mol, heat capacity of water is 75.2 J/mol-K. 60.1 kJ 75.2 kJ 135 kJ 601 kJ 676 kJ

47. Correct Answer: There are 100 moles of ice, so the enthalpy of fusion is: DH =(6.01 kJ/mol)(100 mol) = 601 kJ. To raise the water temperature 10°C requires q = (75.2 J/mol-K)(100 mol)(10°C ) = 75.2 kJ. Total energy = 601 kJ +75 kJ = 676 kJ 60.1 kJ 75.2 kJ 135 kJ 601 kJ 676 kJ

48. D B Pressure A C Temperature In the unlabeled phase diagram below, the line segment from A to B separates which two phases? Gas-liquid Liquid-solid Solid-gas

49. D B Pressure A C Temperature Correct Answer: Gas-liquid Liquid-solid Solid-gas

50. Quartz is an example of which type of solid: crystalline or amorphous? Crystalline Amorphous