→k k k(g) → k(s) -...

www.njctl.org AP Chemistry States of Matter

PSI AP Chemistry: States of Matter Name____________________________ Multiple Choice Review Part A: Phase Changes

1. Which of the following phase changes would be endothermic? (A) K(l) → K(s) (B) K(g) → K(l) (C) K(s) →K(g) (D) K(g) → K(l) (E) K(g) → K(s)

2. Which of the following would be true when water condenses?

I. The potential energy of the substance decreases. II. The kinetic energy of the surroundings increases.

III. The distance between the molecules increases.

(A) I only (B) II only (C) III only (D) I and II only (E) I and III only

3. As a solid element melts, the atoms become ________ and they have __________

attraction for one another. (A) more separated, more (B) more separated, less (C) closer together, more (D) closer together, less (E) larger, greater

4. In liquids, the attractive intermolecular forces are __________.

(A) very weak compared with kinetic energies of the molecules (B) not strong enough to hold molecules relatively close together (C) strong enough to keep the molecules confined to vibrating about their fixed

lattice points (D) not strong enough to keep molecules from moving past each other (E) strong enough to hold molecules relatively close together but not strong enough

to keep molecules from moving past each other

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5. Of the following, __________ is an exothermic process.

(A) melting (B) subliming (C) freezing (D) boiling (E) All of the above are exothermic.

6. For which of the following are covalent bonds being formed?

(A) CO2(l) --> CO2(s)

(B) CO2(g) --> CO2(l)

(C) C(g) --> C(s)

(D) C(l) --> C(s)

(E) NaCl(g) --> NaCl(l)

7. Which of the following are true regarding the vaporization of water at 100oC.

I. The rate of liquid formation is greater than that of vapor formation at 1 atm. II. The liquid and vapor phase are in equilibrium at 1 atm.

III. The liquid and vapor phase are in equilibrium at any pressure.

(A) I only (B) II only (C) III only (D) I and II only (E) II and III only

8. Which of the following correctly ranks the materials from lowest to highest melting

point? (A) Ca < Mg< Sr (B) NaCl < CaO < MgO (C) CH4 < CI4 < CCl4 (D) I2 < Br2 < F2

(E) K < NH3 < I2



9. The melting point of CaO is higher than that of NaCl. Explanations for this observation include which of the following?

I. Ca2+ is more positively charged than Na+ II. O2¯ is more negatively charged than Cl¯

III. NaCl has an increased coulombic attraction compared to CaO

(A) II only (B) I and II only (C) I and III only (D) II and III only (E) I, II, and III

10. Which of the following are true regarding the heat of fusion of a material?

I. The heat of fusion is the amount of energy that is required to melt a given quantity of material.

II. The amount of energy released when a substance freezes is equal to the energy absorbed when it melts.

III. The heat of fusion depends on the strength of the particle interactions within the solid.

(A) I only (B) II only (C) III only (D) I and II only (E) I, II, and III

11. Using the date below, which of the following statements is true.

Heat of Fusion (kJ/mol)

Na: 2.60 Mg: 8.70

K: 2.33 Ca: 8.54

(A) The metallic bonding interaction becomes weaker as the elements get larger,

therefore more energy is required to melt the substance. (B) More energy is required to melt an element as the particle interactions become

weaker. (C) The heat of fusion is not affected by the strength of the particle interaction. (D) The increased dispersion forces of Mg account for its large heat of fusion. (E) None of the above



12. Which of the following would have the lowest heat of fusion?

(A) Na (B) Li (C) K (D) Mg

(E) Be

13. Which of the following would have the highest heat of vaporization?

(A) C3H8

(B) CH3Cl

(C) Ne

(D) H2O

(E) C2H4

14. The substance with the lowest heat of vaporization is __________.

(A) I2 (B) Br2 (C) Cl2 (D) F2 (E) O2

15. If 51.0 g of a solid with a molecular weight of 102.0 g/mol, which is already at its

melting point, requires 20000 J of heat to melt it, what is the molar enthalpy of fusion, in kJ mol-1?

(A) 0.39 kJ mol-1 (B) 2.5 x 10-2 kJ mol-1 (C) 4.0 x 105 kJ mol-1 (D) 1.0 x 10-2 kJ mol-1 (E) 392 kJ mol

16. How many grams of water must have been present if 123000 J of energy were

needed to vaporize the sample? (The heat of vaporization of water is 41 kJ/mol)

(A) 54.0 g (B) 54000 g (C) 3.0 x 10-3 g (D) 2.2 g (E) 3.0 g



17. Calculate the heat of fusion (kJ/mol) for ethylene glycol (C2H6O2) based on the

following data. When a 62.0 gram sample of ethylene glycol was melted in in a 1000 gram sample of water, the temperature of the water dropped by 2.38 degrees.

(A) 160 kJ/mol (B) 10 kJ/mol (C) 100 kJ/mol (D) 20 kJ/mol (E) 15 kJ/mol

18. In a heating curve or cooling curve, what is happening during the diagonal portions

of the graph?

(A) The substance is being warmed or cooled so no changes of state are occurring. (B) The temperature is changing so changes of state are occurring. (C) The temperature is changing so no heat is being added or subtracted from the

system. (D) The material is merely reacting to form a new compound. Its chemical bonds are

being broken. (E) None of the above

Use the heating curve below to answer questions 19 – 23.

19. Which sement(s) represent the kinetic energy increasing?

(A) AB, CD, EF (B) BC, DE (C) AB, BC (D) CD, DE (E) AB, EF



20. The slope of the __________ segment corresponds to the heat capacity of the liquid of the substance.

(A) AB (B) BC (C) CD (D) DE (E) EF

21. The heat flow into the sample in the segment __________ will yield the value of the

ΔHfusion of this substance.


22. The phase changes B → C and D → E are not associated with temperature increases

because the heat energy is used up to __________.

(A) increase distances between molecules (B) break intramolecular bonds (C) rearrange atoms within molecules (D) increase the velocity of molecules (E) increase the density of the sample

23. At which segment are coulombic attractions being broken?


24. How much energy is required to convert a 6.5 g ice cube at -10.0oC to water vapor at

150oC? (Specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. ∆Hfus = 6.01 kJ/mol, and ∆Hvap = 40.67 kJ/mol.)

(A) 203.07 (B) 478.40 (C) 20.31 (D) 3467.71 (E) 17.05



25. On the phase diagram below, segment _______ corresponds to the conditions of temperature

and pressure under which the solid and the gas of the substance are in equilibrium. (A) AB (B) AC (C) AD (D) CD (E) BC

26. On the phase diagram shown above, the coordinates of point ___ correspond to the critical temperature and pressure.

(A) A (B) B (C) C (D) D (E) E

27. The phase diagram of a substance is given below. This substance is a _____ at 25oC and 1.0 atm. (A) solid (B) liquid (C) gas (D) supercritical fluid (E) crystal

28. The normal boiling point of the substance with the phase diagram shown is _____ oC. (A) 10 (B) 20 (C) 30 (D) 40 (E) 50



29. If the substance has its pressure increased isothermally at -10o C, from 0.1 atm to 2 atm, what phase change will it undergo?

(A) Condensation (B) Evaporation (C) Sublimation (D) Deposition (E) Melting

Part B: Solids, Liquids & Gases

30. Which of the following is true regarding the solid state?

(A) It is significantly more compressible than the gas state (B) The viscosity is less than the liquid state (C) The density is greater than the liquid state for most materials (D) The Coulombic attractions are weaker than in the gas state (E) The potential energy of the molecules is greater than in the liquid state

31. Which of the following would be TRUE when a liquid evaporates?

(A) It will become less compressible (B) It will become more dense (C) The coulombic attractions will decrease (D) The viscosity will increase (E) The potential energy of the molecules will decrease

32. Which of the following is FALSE regarding ionic solids?

(A) Formed from elements with large electronegativity differences (B) Have high melting points due to strong intramolecular forces (C) Conduct electricity only in the liquid state where ions are free to move (D) Conduct electricity in the solid and liquid state where ions are free to move (E) All of the above are true

33. Which of the following substances would be characterized by delocalized electrons

and high melting points?

(A) NaI (B) SiO2 (C) H2O (D) C(graphite) (E) Al



34. Which of the following substances is not characterized as a covalent network solid?

(A) C(diamond) (B) C(graphite) (C) C12H22O11(sucrose) (D) SiO2(quartz) (E) All of the above are covalent network solids

35. Solid CO2 is best characterized as which of the following?

(A) Ionic solid (B) Metallic solid (C) Covalent network solid (D) Covalent molecular solid

36. How are network solids, such as diamond, C, and quartz, SiO2, distinguished from

molecular crystals such as I2?

(A) Network solids have very high melting points (B) Network solids are ionic, while molecular ones are covalent substances (C) Network solids dissolve in water; molecular ones do not (D) Network solids are excellent conductors of electricity, while molecular crystals

are conconductors (E) Network solids have individual molecules of fixed size; molecular crystals do not

37. Which of the following correctly ranks the solids by increasing melting point?

(A) NH3 < C2H6 < MgO < KCl

(B) C2H6 < NH3 < MgO < KCl

(C) C2H6 < NH3 < KCl < MgO

(D) MgO < KCl < CH4 < NH3

(E) C2H6 < KCl < MgO < NH3

38. Which of the following would correctly rank the substances below from lowest to

highest boiling points at 1 atm?

(A) F2 < N2< O2

(B) Sr < Ca < Mg (C) KCl < KBr < KI (D) He < C2H6 < H2

(E) Li < Na < CH3OH



39. Viscosity is ____________.

(A) the "skin" on a liquid surface caused by intermolecular attraction (B) the resistance to flow (C) the same as density (D) inversely proportional to molar mass (E) unaffected by temperature

40. Which statements about viscosity are true?

I. Viscosity increases as temperature decreases.

II. Viscosity increases as molecular weight increases. III. Viscosity increases as intermolecular forces increase.

(A) (I) only (B) (II) and (III) (C) (I) and (III) (D) none of the above (E) all of the above

41. Which liquid would have the highest viscosity at room temperature?

(A) C8H17NH2 (B) C7H14 (C) C9H18 (D) C5H12 (E) CH3NH2

42. The kinetic-molecular theory predicts that pressure rises as the temperature of a

gas increases because __________.

(A) the average kinetic energy of the gas molecules decreases (B) the gas molecules collide more frequently with the wall (C) the gas molecules collide less frequently with the wall (D) the gas molecules collide more energetically with the wall (E) both the gas molecules collide more frequently with the wall and the gas

molecules collide more energetically with the wall

43. Which of the following is not part of the kinetic-molecular theory?

(A) Atoms are neither created nor destroyed by ordinary chemical reactions. (B) Attractive and repulsive forces between gas molecules are negligible. (C) Gases consist of molecules in continuous, random motion. (D) Collisions between gas molecules do not result in the loss of energy. (E) The volume occupied by all of the gas molecules in a container is negligible

compared to the volume of the container.



44. A gas in a rigid container registers a pressure of 1.0 atm at 0oC. If the temperature is increased to oC, which of the following would be TRUE?

(A) The volume of the container will decrease. (B) The inter-molecular distances will increase (C) The frequency of collisions will increase (D) The average kinetic energy of the gas molecules will decrease (E) None of these

45. A sample of gas (24.2g) initially at 4.00 atm was compressed from 8.00 L to 2.00 L at

constant temperature. After the compression, the gas pressure was _____ atm.

(A) 4.00 (B) 2.00 (C) 1.00 (D) 8.00 (E) 16.0

46. A balloon originally had a volume of 4.39 L at 44øC and a pressure of 729 torr. The

balloon must be cooled to ____øC to reduce its volume to 3.78 L (at constant pressure).

(A) 38 (B) 0 (C) 72.9 (D) 273 (E) 546

47. If 3.21 mol of a gas occupies 56.2 L at 44øC and 793 torr, 5.29 mol of this gas

occupies _____ L under these conditions.

(A) 14.7 (B) 61.7 (C) 30.9 (D) 92.6 (E) 478

48. A gas originally at 27øC and 1.00 atm pressure in a 3.9 L flask is cooled at constant

pressure until the temperature is 11øC. The new volume of the gas is _________ L.

(A) 0.27 (B) 3.7 (C) 3.9 (D) 4.1 (E) 0.24



49. Helium gas is cooled in a closed rigid container until its absolute temperature is halved. Which of the following is also halved?

(A) The moles of gas (B) The density of the gas (C) The pressure of the gas (D) The average distance between the gas particles (E) None of the above

50. Which of the following would be TRUE regarding the density of a gas?

(A) Density and pressure are inversely proportional. (B) Density and volume are directly proportional. (C) Density and temperature are inversely proportional. (D) Density and moles are inversely proportional. (E) All of the above are true.

51. A gas with a density of 1.0 g/L is heated from 200 K to 400 K and the pressure is

dropped from 200 mbar to 100 mbar. Which of the following would be the correct expression for the new density?

(A) d = 1. 0g

L x

200 K

400 K x

200 mbar

100 mbar

(B) d = 1. 0g

L x

400K

200 K x

200 mbar

100 mbar

(C) d = 1. 0g

L x

200 K

400 K x

100 mbar

200 mbar

(D) d = 1. 0g

L x

400 K

200 K x

100 mbar

200 mbar

52. A 0.25 mole sample of oxygen gas in an isobaric chamber is heated from 100 K to

300 K. What is the density of the gas at 300 K if the gas occupies a volume of 4 L at 100 C?

(A) 0.67 g/L (B) 6.0 g/L (C) 0.33 g/L (D) 18.75 g/L (E) 1.33 g/L



53. Nitrogen gas has a density of 0.72 g/L @STP. Helium gas has a density of 0.18 g/L @STP. To what pressure (in atm) must the nitrogen gas be decreased to decrease its density to be equal to that of helium? Assume a rigid container and isothermal compression.

(A) 4.0 atm (B) 0.25 atm (C) 2.0 atm (D) 1.5 atm (E) 0.50 atm

54. The mass of nitrogen dioxide contained in a 4.32 L vessel at 48°C and 1.40 atm is

_______ g.

(A) 5.35 × 104 (B) 53.5 (C) 10.6 (D) 70.5 (E) 9.46 × 10-2

55. A sample of oxygen gas (41.6 g) occupies __________ L at 22°C and 4.5 atm.

(A) .079 (B) .52 (C) 13 (D) .032 (E) 7.0

56. A 1.44-g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure

of 1.00 atm and a temperature of 100.0°C. The unknown gas is __________.

(A) argon (B) helium (C) krypton (D) neon (E) xenon

57. Of the following gases, __________ has density of 2.104 g/L at 303 K and 1.31 atm.

(A) He (B) Ne (C) Ar (D) Kr (E) Xe



58. The density of ammonia gas in a 4.32 L container at 837 torr and 45.0°C is __________ g/L.

(A) 3.86 (B) 0.719 (C) 0.432 (D) 0.194 (E) 4.22 × 10-2

59. Hydrogen gas is collected in a eudiometer via the reaction of magnesium metal with

hydrochloric acid. Use the data below to find the molar volume of the gas @STP. Mass of hydrogen gas collected = 0.0052 grams Volume of gas collected @ 28oC = 61.3 mL Pressure of gas collected @ 28o C = 747 mm Hg

(A) 23.0 L/mol (B) 20.5 L/mol (C) 19.75 L/mol (D) 21.0 L/mol (E) 22.0 L/mol

60. The pressure in a 12.2 L vessel that contains 2.34 g of carbon dioxide, 1.73 g of sulfur dioxide, and 3.33 g of argon, all at 42 °C is __________ mm Hg.

(A) 263 (B) 134 (C) 395 (D) 116 (E) 0.347



Use the information below to answer questions 61 -63.

Each of the two closed rigid vessels contains a different gas. The temperature of each gas is 298K.

61. What is the ratio of the number of H2 and Ar gas particles respectively?

(A) 4:3 (B) 2:3 (C) 2:1 (D) 1:3 (E) 3:1

62. If the pressure of H2 in the first vessel is 2.0 atm, what is the pressure of Ar in the

second vessel?

(A) 1.0 atm (B) 2.0 atm (C) 3.0 atm (D) 4.0 atm (E) Cannot be determined

63. When the two gases are combined in the 2.0 L vessel which of the following

represents the correct partial and total pressures?

(A) PH2 = 1.0 atm , PAr = 1.5 atm, Ptotal = 2.5 atm

(B) PH2 = 2.0 atm , PAr = 3.0 atm, Ptotal = 5.0 atm

(C) PH2 = 1.0 atm , PAr = 2.0 atm, Ptotal = 3.0 atm

(D) PH2 = 2.0 atm , PAr = 3.0 atm, Ptotal = 5.0 atm

(E) PH2 = 1.0 atm , PAr = 3.0 atm, Ptotal = 4.0 atm



64. A mixture of gases contains 5.0 moles of O2 and 10 moles of He. If the total pressure

of the mixture is 1.5 atm, what is the partial pressure of O2?

(A) 1.5 atm (B) 4.5 atm (C) 7.5 atm (D) 0.50 atm (E) 2.5 atm

65. A mixture of Xe, Kr, and Ar has a total pressure of 6.70 atm. What is the mole

fraction of Kr if the partial pressures of Xe and Ar are 1.60 atm and 2.80 atm, respectively.

(A) 0.174 (B) 0.256 (C) 0.343 (D) 0.481 (E) 0.570

66. Hydrogen gas is collected over water at 30 °C. The total pressure of the sample is

728 mmHg. At 30 °C, the vapor pressure of water is 31.8 mmHg. What is the partial pressure of the hydrogen gas?

(A) 31.8 mm Hg (B) 759.8 mm Hg (C) 758 mm Hg (D) 728 mm Hg (E) 696.2 mm Hg

67. Sodium hydride reacts with excess water to produce aqueous sodium hydroxide and

hydrogen gas: NaH (s) + H2O (l) → NaOH (aq) + H2 (g)

A sample of NaH weighing __________ g will produce 982 mL of gas at 28.0°C and 765 torr, when the hydrogen is collected over water. The vapor pressure of water at this temperature is 28 torr.

(A) 2.93 (B) 0.960 (C) 0.925 (D) 0.0388 (E) 925



68. At 333 K, which of the pairs of gases below would have the most nearly identical rates of effusion?

(A) N2O and NO2 (B) CO and N2 (C) N2 and O2 (D) CO and CO2 (E) NO2 and N2O4

69. Arrange the following gases in order of increasing average molecular speed at 25°C.

He, O2, CO2, N2

(A) He < N2 < O2 < CO2 (B) He < O2 < N2 < CO2 (C) CO2 < O2 < N2 < He (D) CO2 < N2 < O2 < He (E) CO2 < He < N2 < O2

70. A sample of oxygen gas was found to effuse at a rate equal to two times that of an

unknown gas. The molecular weight of the unknown gas is __________ g/mol.

(A) 64 (B) 128 (C) 8 (D) 16 (E) 8.0

71. Two gases with unequal masses are injected into opposite ends of a long tube at the

same time and allowed to diffuse toward the center. They should begin to mix

(A) in approximately five minutes. (B) closer to the end that holds the heavier gas. (C) closer to the end that holds the lighter gas. (D) exactly in the middle. (E) Immediately after injection.

72. A real gas will behave most like an ideal gas under conditions of __________.

(A) high temperature and high pressure (B) high temperature and low pressure (C) low temperature and high pressure (D) low temperature and low pressure (E) STP



73. An ideal gas differs from a real gas in that the molecules of an ideal gas __________.

(A) have no attraction for one another (B) have appreciable molecular volumes (C) have a molecular weight of zero (D) have no kinetic energy (E) have an average molecular mass

74. Which of the following is FALSE regarding real gases.

(A) The larger the gas molecule, the more real and less ideal it behaves (B) The greater the inter-molecular forces, the less ideal and more real the gas will

behave (C) Gases behave most ideal (less real) at high temperatures and low pressures. (D) Their measured pressure is greater than an ideal gas (E) Real gases experience coulombic attractions/repulsions between molecules.

75. Which one of the following gases would deviate the least from ideal gas behavior?

(A) Ne (B) CH3Cl (C) Kr (D) CO2 (E) F2

76. When gases are treated as real, the actual volume occupied by gas molecules

__________ the pressure exerted and the attractive forces between gas molecules __________ the pressure exerted, as compared to an ideal gas.

(A) decreases, increases (B) increases, increases (C) increases, decreases (D) does not affect, decreases (E) does not affect, increases

Question 77-81 refer to three gases in closed rigid containers, under the conditions



given in the table below

Container A B C

Gas NH3 Ar He

Temperature (oC) 25 25 25

Pressure (atm) 2.0 1.0 1.0

Volume (L) 3.0 3.0 3.0

Molar Mass (g/mol) 17 40 4

77. Which sample would have the greatest number of gas particles?

(A) Container A (B) Container B (C) Container C (D) All have the same number of particles (E) Not enough information

78. Which sample would have the fastest moving gas molecules?

(A) Container A (B) Container B (C) Container C (D) All have the same speed at this temperature (E) Not enough information

79. Which sample would have the greatest average kinetic energy?

(A) Container A (B) Container B (C) Container C (D) All have the same average kinetic energy at this temperature (E) Not enough information

80. Which sample would have the greatest density?

(A) Container A (B) Container B (C) Container C (D) All have the same density (E) Not enough information



81. If the temperature of each gas was decreased at constant pressure until condensation occurs, which gas will condense first?

(A) Container A (B) Container B (C) Container C (D) All will condense at the same temperature (E) Not enough information

Answers

1. C 2. D 3. B 4. E 5. C 6. C 7. B 8. B 9. B 10. E 11. A 12. C 13. D 14. E 15. D 16. A 17. B 18. A 19. B 20. C 21. B 22. A 23. D 24. C 25. B 26. B 27. B 28. D 29. D 30. C 31. C 32. D 33. E 34. C 35. D

36. A 37. C 38. B 39. B 40. E 41. A 42. E 43. A 44. C 45. E 46. B 47. D 48. B 49. C 50. C 51. C 52. A 53. B 54. C 55. E 56. E 57. C 58. B 59. D 60. A 61. B 62. C 63. A 64. D 65. C 66. E 67. C 68. B 69. C 70. B

71. B 72. B 73. A 74. D 75. A 76. C 77. A 78. C 79. D 80. B 81. A


→k k k(g) → k(s) -...

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