Chem 2 Chapter 11 Multiple Choice Questions

67) Which of the following is considered an ionic solid? A) (NH4)2CO3 B) CCl4 C) SeBr2 D) XeF4 E) None of these is an ionic solid.

A) (NH4)2CO3

48) Determine the vapor pressure (in torr) of a substance at 36°C, whose normal boiling point is 84°C and has a ΔHvap of 22.1 kJ/mol. A) 239 torr B) 31.8 torr C) 41.8 torr D) 147 torr E) 98 torr

A) 239 torr

97) Ethyl chloride, C2H5Cl, is used as a local anesthetic. It works by cooling tissue as it vaporizes; its heat of vaporization is 26.4 kJ/mol. How much heat could be removed by 20.0 g of ethyl chloride? A) 8.18 kJ B) 341 kJ C) 528 kJ D) 3410 kJ

A) 8.18 kJ

37) How much energy is required to vaporize 98.6 g of ethanol (C2H5OH) at its boiling point, if its ΔHvap is 40.5 kJ/mol? A) 86.7 kJ B) 11.5 kJ C) 18.9 kJ D) 52.8 kJ E) 39.9 kJ

A) 86.7 kJ

26) Which substance below has the strongest intermolecular forces? A) A2X, ΔHvap = 39.6 kJ/mol B) BY2, ΔHvap = 26.7 kJ/mol C) C3X2, ΔHvap = 36.4 kJ/mol D) DX2, ΔHvap = 23.3 kJ/mol E) EY3, ΔHvap = 21.5 kJ/mol

A) A2X, ΔHvap = 39.6 kJ/mol

29) Place the following substances in order of increasing boiling point. CH3CH2OH Ar CH3OCH3 A) Ar < CH3OCH3 < CH3CH2OH B) CH3CH2OH < Ar < CH3OCH3 C) CH3CH2OH < CH3OCH3 < Ar D) CH3OCH3< Ar < CH3CH2OH E) Ar < CH3CH2OH < CH3OCH3 Answer: A

A) Ar < CH3OCH3 < CH3CH2OH Note: CH3CH2OH has hydrogen bonding, and CH3OCH3 has a higher molecular weight than Ar

18) Choose the pair of substances that are most likely to form a homogeneous solution. A) C6H14 and C10H20 B) LiBr and C5H12 C) N2O4 and NH4Cl D) C6H14 and H2O E) None of the pairs above will form a homogeneous

A) C6H14 and C10H20

16) Which has the highest boiling point? A) CH3OH B) CH3NH2 C) CO D) N2

A) CH3OH

10) Choose the molecule or compound that exhibits dispersion forces as its strongest intermolecular force. A) Cl2 B) CO C) HF D) NaCl E) All of these have intermolecular forces stronger than dispersion.

A) Cl2

85) In liquid propanol, CH3CH2CH2OH which intermolecular forces are present? A) Dispersion, hydrogen bonding and dipole-dipole forces are present. B) Only dipole-dipole and ion-dipole forces are present. C) Only dispersion and dipole-dipole forces are present. D) Only hydrogen bonding forces are present.

A) Dispersion, hydrogen bonding and dipole-dipole forces are present.

65) Which of the following substances should have the highest melting point? A) Fe B) Ne C) Xe D) N2 E) CO

A) Fe

91)Which of the following compounds has the highest boiling point? A) H2O B) HCl C) H2S D) NH3

A) H2O

15) Place the following compounds in order of decreasing strength of intermolecular forces. HF O2 CO A) HF > CO2 > O2 B) HF> O2> CO2 C) O2> CO2 > HF D) CO2> HF > O2 E) CO2> O2> HF

A) HF > CO2 > O2

20) Choose the substance with the highest surface tension. A) HOCH2CH2OH B) CH2F2 C) CH3CH2F D) CH3CH2OH E) CH3CH2CH3

A) HOCH2CH2OH Note: Because of hydrogen bonding

3) Give the change in condition to go from a liquid to a gas. A) Increase heat or reduce pressure. B) Increase heat or increase pressure. C) Cool or reduce pressure D) Cool or increase pressure. E) None of the above

A) Increase heat or reduce pressure.

69) If all of the following are in solid phase, which is considered a non-bonding atomic solid? A) Ne B) Fe C) I2 D) Ca E) Li

A) Ne

122) Which statement is correct? A) The normal boiling point a liquid depends on the atmospheric pressure. B) The normal boiling point a liquid depends on the amount of the liquid. C) The normal boiling point a liquid depends on the temperature. D) The normal boiling point a liquid depends on the shape and size of the container.

A) The normal boiling point a liquid depends on the atmospheric pressure.

49) Define sublimation. A) The phase transition from solid to gas. B) The phase transition from gas to solid. C) The phase transition from gas to liquid. D) The phase transition from liquid to gas. E) The phase transition from liquid to solid.

A) The phase transition from solid to gas.

25) Which of the following statements is true? A) Vapor pressure increases with temperature. B) Hydrogen bonds are stronger than covalent bonds. C) Intermolecular forces hold the atoms in molecules together. D) Dispersion forces are generally stronger than dipole-dipole forces. E) None of the above are true.

A) Vapor pressure increases with temperature.

24) Identify the term used to describe the ability of a liquid to flow against gravity up a narrow tube. A) capillary action B) viscosity C) surface tension D) density E) None of the above

A) capillary action

73) What type of force is CH2F2? A) dipole-dipole forces B) dispersion forces C) ion-dipole forces D) ionic bond E) hydrogen bonding

A) dipole-dipole forces

51) Give the phase transition that occurs as the temperature of dry ice increases. A) from solid to gas B) from gas to solid C) from liquid to gas D) from liquid to solid E) from solid to liquid

A) from solid to gas

111) The heat of vaporization of water at 100°C is 40.66 kJ/mol. Calculate the quantity of heat that is absorbed/released when 9.00 g of steam condenses to liquid water at 100°C. A) 20.3 kJ of heat are absorbed. B) 20.3 kJ of heat are released. C) 81.3 kJ of heat are absorbed. D) 81.3 kJ of heat are released.

B) 20.3 kJ of heat are released

38) How much energy is required to vaporize 158 g of butane (C4H10) at its boiling point, if its ΔHvap is 24.3 kJ/mol? A) 15.1 kJ B) 66.1 kJ C) 89.4 kJ D) 11.2 k E) 38.4 kJ

B) 66.1 kJ

52) How much energy is required to heat 36.0 g H2O from a liquid at 65°C to a gas at 115°C? The following physical data may be useful: ΔHvap= 40.7 kJ/mol Cliq= 4.18 J/g°C Cgas = 2.01 J/g°C Csol= 2.09 J/g°C Tmelting = 0°C Tboiling= 100°C A) 63.5 kJ B) 87.7 kJ C) 10.9 kJ D) 52.7 kJ E) 91.7 kJ

B) 87.7 kJ

33) Choose the substance with the lowest vapor pressure at a given temperature. A) CO2 B) BeCl2 C) BF3 D) He E) PF5

B) BeCl2

110)Which is expected to have the largest dispersion forces? A) C3H8 B) C12H26 C) F2 D) BeCl2

B) C12H26

83) Which is expected to have the largest dispersion forces? A) C3H8 B) C12H26 C) F2 D) BeCl2

B) C12H26

21) Choose the substance with the lowest surface tension. A) CH3SH B) CH3CH2CH2CH3 C) C6H6 D) H2O E) (CH3)2CO

B) CH3CH2CH2CH3 Note: Among all the compounds n-butane has the weakest dispersion forces and hence lowest surface tension.

86) Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions? A) H2 B) HI C) CO2 D) CH3NH2

B) HI

16) Place the following compounds in order of decreasing strength of intermolecular forces. I.CH3CH2CH2CH2CH2CH3 II. (CH3)3CCH3 III.(CH3)3CCH2CH3 A) III > II > I B) I > III > II C) I > II > III D) II > III > I E) III > I > II

B) I > III > II

30) Choose the substance with the highest boiling point. A) CH4 B) KI C) CS2 D) HF E) I2

B) KI Note: KI is an ionic solid, therefore the strongest bong

19) Choose the pair of substances that are most likely to form a homogeneous solution. A) CCl4 and SCl2 B) NF3 and SO2 C) CO and C6H6 D) NH2CH3 and CH4 E) None of the pairs above will form a homogeneous

B) NF3 and SO2

11) Choose the molecule or compound that exhibits dipole-dipole forces as its strongest intermolecular force. A) H2 B) SO2 C) NH3 D) CF4 E) BCl3

B) SO2

) Which of the following statements is true? A) Intermolecular forces are generally stronger than bonding forces. B) Until a certain point, the potential energy of molecules decrease as they get closer to one another. C) Energy is given off when the attraction between two molecules is broken. D) Increasing the pressure on a solid usually causes it to become a liquid. E) None of the above are true.

B) Until a certain point, the potential energy of molecules decrease as they get closer to one another.

72) What type of force is CH3CH3? A) dipole-dipole forces B) dispersion forces C) ion-dipole forces D) ionic bond E) hydrogen bonding

B) dispersion forces

Identify the characteristics of a liquid. A) indefinite shape and volume B) indefinite shape, but definite volume C) definite shape and volume D) none of the above E) all of the above

B) indefinite shape, but definite volume

87) The normal boiling point for H2Se is higher than the normal boiling point for H2S. This can be explained by A) larger dipole-dipole forces for H2Se. B) larger dispersion forces for H2Se. C) larger hydrogen-bond forces for H2Se. D) larger dipole-dipole forces, larger dispersion forces, and larger hydrogen-bond forces for H2Se.

B) larger dispersion forces for H2Se.

93) The enthalpy change for converting 1.00 mol of ice at -50.0°C to water at 70.0°C is The specific heats of ice, water, and steam are and respectively. For H2O, ∆Hfus = 6.01 kJ/mol, and∆Hvap =40.67 kJ/mol. A) 12.28 B) 6.41 C) 13.16 D) 7154 E) 9.40

C) 13.16

45) Determine ΔHvap for a compound that has a measured vapor pressure of 24.3 torr at 273 K and 135 torr at 325 K. A) 41 kJ/mol B) 79 kJ/mol C) 24 kJ/mol D) 13 kJ/mol E) 34 kJ/mol

C) 24 kJ/mol

98) How much heat is released when 105 g of steam at 100.0°C is cooled to ice at -15.0°C? The enthalpy of vaporization of water is 40.67 kJ/mol, the enthalpy of fusion for water is 6.01 kJ/mol, the molar heat capacity of liquid water is 75.4 J/(mol ·°C), and the molar heat capacity of ice is 36.4 J/(mol ·°C). A) 54.8 kJ B) 273 kJ C) 319 kJ D) 347 kJ

C) 319 kJ

2) Calculate the total quantity of heat required to convert 25.0 g of liquid CCl4 from 35.0°C to gaseous CCl4 at 76.8°C (the normal boiling point for CCl4). The specific heat of CCl4(l) is0.857 J/(g · °C) its heat of fusion is3.27 kJ/mol,and its heat of vaporization is 29.82 kJ/mol. A) 0.896 kJ B) 1.43 kJ C) 5.74 kJ D) 6.28 kJ

C) 5.74 kJ

96) Ethanol (C2H5OH) melts at -114°C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g·K and 2.3 J/g·K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C? A) 207.3 kJ B) -12.7 kJ C) 6.91 kJ D) 4192 kJ E) 9.21 kJ

C) 6.91 kJ

53) How much energy must be removed from a 125 g sample of benzene (molar mass = 78.11 g/mol) at 425.0 K to liquify the sample and lower the temperature to 335.0 K? The following physical data may be useful. ΔHvap= 33.9 kJ/mol ΔHfus= 9.8 kJ/mol Cliq= 1.73 J/g°C Cgas = 1.06 J/g°C Csol= 1.51 J/g°C Tmelting = 279.0 K Tboiling= 353.0 K A) 38.9 kJ B) 95.4 kJ C) 67.7 kJ D) 54.3 kJ E) 74.4 kJ

C) 67.7 kJ

12) Choose the compound that exhibits hydrogen bonding as its strongest intermolecular force. A) SCl2 B) C2H6 C) CH3OH D) CH2F2 E) None of the above compounds exhibit hydrogen bonding.

C) CH3OH Note: Because of hydrogen bonding

31) Choose the substance with the lowest boiling point. A) H2S B) NBr3 C) F2 D) CF2H2 E) H2O2 Answer: C

C) F2 Note: weakest bond, it will only have a small dipole moment

43) Place the following substances in order of decreasing boiling point. H2O N2 CO A) CO > H2O > N2 B) N2> CO > H2O C) H2O > CO > N2 D) CO > N2> H2O E) N2> H2O > CO

C) H2O > CO > N2

22) Choose the substance with the highest viscosity. A) (CH3CH2)2CO B) C2H4Cl2 C) HOCH2CH2CH2CH2OH D) CF4 E) C6H14

C) HOCH2CH2CH2CH2OH Note: Because of the long carbon chain and hydrogen bonding

34) Which of the following substances would you predict to have the highest ΔHvap? A) CH3Cl B) HCl C) HOCH2CH2OH D) CH3CH2OH E) CH3CH2CH2CH3

C) HOCH2CH2OH

66) Which of the following is considered a molecular solid? A) Cu B) NH4NO3 C) I2 D) Xe E) None of these is a molecular solid.

C) I2

82) Which has the smallest dipole-dipole forces? A) CH3Cl B) HBr C) O2 D) NO

C) O2

107) Which of the following forms an ionic solid? A) Ag B) C7H15NH2 C) RbI D) SO3

C) RbI

Identify the phase in which the water molecules are closest together. A) gas B) dry ice C) solid D) liquid

C) Solid

121) Which of the following statements is not correct regarding rate of vaporization of a liquid? A) The rate of vaporization increases with increasing temperature. B) The rate of vaporization increases with increasing surface area. C) The rate of vaporization increases with increasing intermolecular forces. D) None of the above

C) The rate of vaporization increases with increasing intermolecular forces

56) Identify triple point. A) The temperature, pressure, and density for a gas. B) The temperature at which the boiling point equals the melting point. C) The temperature and pressure where liquid, solid, and gas are equally stable and are in equilibrium. D) The temperature that is unique for a substance .E) The temperature at which the solid and liquid co-exist.

C) The temperature and pressure where liquid, solid, and gas are equally stable and are in equilibrium.

112) What is the strongest type of intermolecular force present in Cl2? A) ion-dipole B) dipole-dipole C) dispersion D) hydrogen bonding E) none of the above

C) dispersion

5) What is the strongest type of intermolecular force present in H2? A) ion-dipole B) dipole-dipole C) dispersion D) hydrogen bonding E) None of the above

C) dispersion

9) Identify the weakest type of intermolecular forces. A) ion-dipole forces B) hydrogen bonding C) dispersion forces D) dipole-dipole forces E) ionic forces

C) dispersion forces

7) What is the strongest type of intermolecular force present in NH2CH3? A) dispersion B) dipole-dipole C) hydrogen bonding D) ion-dipole E) None of the above

C) hydrogen bonding

8) What type of intermolecular force causes the dissolution of NaCl in water? A) hydrogen bonding B) dipole-dipole forces C) ion-dipole force D) dispersion forces E) None of the above

C) ion-dipole force

74) What type of force is LiI +H20 ? A) dipole-dipole forces B) dispersion forces C) ion-dipole forces D) ionic bond E) hydrogen bonding

C) ion-dipole forces

108) Which type of bonding does Sr form upon solidification? A) covalent network B) ionic C) metallic D) molecular

C) metallic

54) How much energy is required to heat 87.1 g acetone (molar mass = 58.08 g/mol) from a solid at -154.0°C to a liquid at -42.0°C? The following physical data may be useful. ΔHfus= 7.27 kJ/mol Cliq= 2.16 J/g°C Cgas = 1.29 J/g°C Csol= 1.65 J/g°C Tmelting = -95.0°C A) 8.48 kJ B) 18.5 kJ C) 32.2 kJ D) 29.4 kJ E) 9.97 kJ

D) 29.4 kJ

46) Determine the normal boiling point of a substance whose vapor pressure is 55.1 mm Hg at 35°C and has a ΔHvap of 32.1 kJ/mol. A) 255 K B) 368 K C) 412 K D) 390. K E) 466 K

D) 390. K

94) The enthalpy change for converting 10.0 g of ice at -25.0°C to water at 80.0°C is ________ kJ. The specific heats of ice, water, and steam are and respectively. For H2O, ∆Hfus = 6.01 kJ/mol, and∆Hvap = 40.67 kJ/mol. A) 12.28 B) 6.16 C) 3870 D) 7.21 E) 9.88

D) 7.21

32) Choose the substance with the highest vapor pressure at a given temperature. A) SiS2 B) RbCl C) CH3SCH3 D) BF3 E) SbH3 Answer: D

D) BF3 Note: The weaker the intermolecular forces are, and the lower the molecular weight is, the higher the vapor pressure will be

35) Which of the following substances would you predict to have the highest ΔHvap? A) Xe B) C6H6 C) SiF4 D) Br2 E) N2 Answer: D

D) Br2

84) Which of the following compounds exhibits hydrogen bonding? A) CH3I B) H2 C) C6H5CH3 D) CH3OH

D) CH3OH

23) Choose the substance with the lowest viscosity. A) Cl3CCCl3 B) Cl2CHCH2Cl C) Cl2CHCHCl2 D) ClCH2CH2Cl E) Cl3CCHCl2

D) ClCH2CH2Cl

13) Place the following compounds in order of increasing strength of intermolecular forces. CO2 F2 NH2CH3 A) NH2CH3< CO2< F2 B) F2< NH2CH3< CO2 C) NH2CH3< F2 < CO2 D) F2< CO2 < NH2CH3 E) CO2< NH2CH3< F2

D) F2< CO2 < NH2CH3

68) Which of the following is considered an atomic solid? A) Br2 B) CsCl C) N2 D) Nb E) None of these is an atomic solid.

D) Nb

44) Place the following substances in order of decreasing boiling point. N2 O2 H2 A) O2> H2 > N2 B) N2> H2> O2 C) N2> O2> H2 D) O2> N2> H2 E) H2> N2> O2

D) O2> N2> H2

27) Give the term for the temperature at which the gas and liquid phases form a supercritical fluid. A) absolute temperature B) definite temperature C) fluid temperature D) critical temperature E) solid temperature

D) critical temperature

6) What is the strongest type of intermolecular force present in CHF3? A) ion-dipole B) dispersion C) hydrogen bonding D) dipole-dipole E) None of the above

D) dipole-dipole

70) What type of force is LiI? A) dipole-dipole forces B) dispersion forces C) ion-dipole forces D) ionic bond E) hydrogen bonding

D) ionic bond

78) Define dynamic equilibrium as it relates to vapor pressure.

Dynamic equilibrium is when the rate of condensation equals the rate of vaporization.

95) The fluorocarbon C2Cl3F3 has a normal boiling point of 47.6°C. The specific heats of C2Cl3F3(l) and C2Cl3F3(g) are 0.91 J/g·K and 0.67 J/g·K, respectively. The heat of vaporization of the compound is 27.49 kJ/mol. The heat required to convert 50.0 g of the compound from the liquid at 50.0°C to the gas at 80.0°C is ________ kJ. A) 8.19 B) 1454 C) 30.51 D) 3031 E) 10.36

E) 10.36

36) How much energy is required to vaporize 48.7 g of dichloromethane (CH2Cl2) at its boiling point, if its ΔHvap is 31.6 kJ/mol? A) 31.2 kJ B) 6.49 kJ C) 55.1 kJ D) 15.4 kJ E) 18.1 kJ

E) 18.1 kJ

55) How much energy must be removed from a 94.4 g sample of benzene (molar mass = 78.11 g/mol) at 322.0 K to solidify the sample and lower the temperature to 205.0 K? The following physical data may be useful. ΔHvap= 33.9 kJ/mol ΔHfus= 9.8 kJ/mol Cliq= 1.73 J/g°C Cgas = 1.06 J/g°C Csol= 1.51 J/g°C Tmelting = 279.0 K Tboiling= 353.0 K A) 17.6 kJ B) 11.8 kJ C) 70.2 kJ D) 10.5 kJ E) 29.4 kJ

E) 29.4 kJ

47) Determine the vapor pressure (in mm Hg) of a substance at 29°C, whose normal boiling point is 76°C and has a ΔHvap of 38.7 kJ/mol. A) 80 mm Hg B) 13 mm Hg C) 21 mm Hg D) 48 mm Hg E) 96 mm Hg

E) 96 mm Hg

60) Why is water an extraordinary substance? A) Water has a low molar mass, yet it is a liquid at room temperature. B) Water is the main solvent within living organisms. C) Water has an exceptionally high specific heat capacity. D) Water has strong hydrogen bonding. E) All of the above

E) All of the above

4) Place the following compounds in order of increasing strength of intermolecular forces. CH4 CH3CH2CH3 CH3CH3 A) CH3CH2CH3< CH4 < CH3CH3 B) CH3CH2CH3< CH3CH3 < CH4 C) CH3CH3< CH4 < CH3CH2CH3 D) CH4< CH3CH2CH3< CH3CH3 E) CH4< CH3CH3 < CH3CH2CH3

E) CH4< CH3CH3 < CH3CH2CH3

109) Identify the compound that does not have dipole-dipole forces as its strongest force. A) CH2Br2 B) CH3OCH3 C) CH3Cl D) HCBr3 E) CO2

E) CO2

64) Which of the following substances should have the highest melting point? A) CO2 B) SrS C) Xe D) F2 E) MgO

E) MgO

17) Choose the pair of substances that are most likely to form a homogeneous solution. A) NaCl and Hg B) C3H8 and C2H5OH C) LiF and C6H14 D) Br2 and PF3 E) NH3 and CH3OH

E) NH3 and CH3OH

28) Place the following substances in order of increasing boiling point. Ne Cl2 O2 A) Ne < Cl2 < O2 B) Cl2< O2 < Ne C) O2< Cl2 < Ne D) Cl2< Ne < O2 E) Ne < O2 < Cl2 Answer: E

E) Ne < O2 < Cl2 Note: Neon gas belongs to noble gases and hence it is a very stable element. Since neon gas has a stable octet configuration, it seldom reacts with other elements which are usually a non-spontaneous reaction. Thus, it takes more thermal energy to break the intermolecular forces in it. Therefore, it boils very slowly and it has the highest boiling point when we compare with neon, oxygen and chlorine that have less strong intermolecular forces in it. The types of forces present are the dispersion forces arising due to the electron distribution fluctuations within these molecules. Oxygen is less heavy than chlorine. Hence, oxygen has the lowest boiling point when comparing chlorine and oxygen.

50) Define fusion. A) The phase transition from solid to gas. B) The phase transition from gas to solid. C) The phase transition from gas to liquid. D) The phase transition from liquid to solid. E) The phase transition from solid to liquid.

E) The phase transition from solid to liquid.

71) What type of force is CH3OH? A) dipole-dipole forces B) dispersion forces C) ion-dipole forces D) ionic bond E) hydrogen bonding

E) hydrogen bonding

75) Why do O, F and N, when bonded to H, form such strong intermolecular attractions to neighboring molecules?

Oxygen, fluorine and nitrogen are all very small and highly electronegative elements. When they bond to hydrogen they form extremely polar bonds. These extremely polar bonds formed between small atoms can get very close to interact with other molecules. The closer the molecules get, the more strongly they can interact. In addition, these three elements usually have lone pair electrons which make the attractions to other molecules even stronger. This type of bonding is called hydrogen bonding.

77) Why does the temperature of a substance stay constant during a phase change such as vaporization?

The energy added to the substance is not used to raise the kinetic energy of the substance. Instead it is "used up" in breaking the intermolecular attractions between particles to take them from a liquid (with intermolecular attractions) to a gas (with no intermolecular attractions).

80) Explain why the boiling point of water is so much higher than other compounds of similar molecular weight.

The hydrogen bonding of the water results in a higher boiling point.

79) Why is the ΔHvap higher than ΔHfus for any given compound?

Vaporizing a substance requires the complete "breaking" of all intermolecular attractions, whereas the melting of a substance only requires the breaking of a portion of the intermolecular attractions. The more intermolecular attractions broken, the more energy used.

76) Define viscosity.

Viscosity is the resistance of a liquid to flow.