Answers to UNIT 7 Self Test:

Part I: Matching

1.  bc        2. ac or d        3. be        4. ab        5. c        6. ad        7. d or ac        8. bd        9. a        10. cd
11. e        12. ae        13. b

Part II: Multiple Choice with explanation

14. d; other answers are in contradiction to the properties of gases.
15. a; average KE is directly proportional to the temperature in the absolute, Kelvin, scale
16. a; intermolecular forces (imfs) in liquids hold particles together

17. b; boiling = temp when vapor press. = atmospheric pressure, sublimation = change from solid to gas, condensation = change of state from gas to liquid

18. a; at 92 C the vapor pressure of water if less than 101.3 kPa, so a lower atmospheric pressure would allow water to boil at a lower temperature

19. a; solids are the most compact state therefore most dense
20. c; imfs are not bonds
21. b; The higher the boiling point the more KE the particles require to escape the imfs in the liquid."
22. c; intra molecular forces are covalent bonds comparatively much stronger than imfs
23. a; "a" gives correct relationship
24. d; any of these attached to the hydrogen allows hydrogen bonding
25. c; "c" is most important and noticeable difference
26. b; at higher elevations the air is thinner, which means less atmospheric pressure
27. b; 2.5 atm x (760 mmHg/1atm) = 1900 mmHg
28. e; a, b & c apply not d! (oops)

***24. a; P = F/area; increasing the area reduces the pressure
25. d; Since volume is 22.4 L and T = 0 C the pressure of 1 mole of any gas would be 1 atm or 101.3 kPa, 2 moles would be 202.6 kPa, so "d" is the correct answer.

26. c; as T goes down the ave KE also goes down
27. b; P is inversely proportional to V
28. d; statements a-c are all true about absolute zero.
29. b; Avogadro's hypothesis

Part III: True-False

30. ST (this pressure is standard, but can vary)        31. AT        32. AT        33. NT        34. ST        35. AT

36. a) AT    b) ST    c) AT    d) NT    e) NT    f) AT    g) NT    h) AT    i) ST    j) AT    k) AT    l) AT    m) NT

37. smells spread out and smoke diffuses

38. B evaporates faster since at 40 C more of B particles are in gas phase.  This means more of B will evaporate in a given time.

39. City A is higher since the b.p. is lower.  Thus the atmospheric pressure at City A would be lower implying a higher elevation.

40. Beaker with hot water added: The added hot water is cooled by the melting process of the ice.  Some of the ice melts but not all leaving the ice and water mixture at the end still at 0 C.  Beaker with ice cubes added:  If the ice cubes are below 0 C in temperature then the freezing of some of the water in the beaker will release heat to warm up the ice until the added cubes temperature reaches that of the mixture, 0 C.

41. He and Rn exhibit only dispersion forces since they can't be polar.  Rn is heavier so the dispersion forces in Rn are stronger, giving it a higher b.p.

42. SO2 is a polar molecule and heavier than non-polar CO2 .  Thus the stronger dispersion forces and dipole-dipole imfs in SO2 mean the SO2 molecules are held more tightly together.  This produces a higher b.p.

43. Fe- metallic solid; SiO2 - covalent network solid; ice - molecular solid; MgO - ionic solid

44. There are three regions on a phase diagram separated by lines.  The regions indicate the pressure and temperature conditions under which a pure substance exists as a solid, liquid or gas.  The lines represent equilibrium conditions of temperature and pressure when two states exist together.  For example the line between the solid and liquid phase lists the melting points of the substance.  The line between liquid and gas phase indicate the boiling points of the substance and the line between the solid and the gas phases indicate the sublimation points.  There is a single temperature and pressure point where all three states exist at the same time, this is called the triple point.

45. Charles' Law: V2 = 3.5L        46. Boyle' Law: P2 = 150 kPa        47. Boyle's Law: V2 = 15 L

48. Ideal: n = 0.0027 mol        49. Ideal: V = 32.4 L        50. Combined Gas Law: V2 = 32 mL

51. Dalton: Ptot = 272 kPa        52. density = 2.79 g/L

53.  Real gas particles have volume and ideal gases do not.  Real gas particles are attracted to one another through intermolecular forces, ideal gases have no i.m.f.s.  Gases are ideal at high temperatures and low pressures.