Chapter 11 Flashcards

The phase diagram for carbon dioxide is shown below. What is the phase that exists at room temperature and pressure (22^oC, 1 atm)?

Answers:

gas

liquid

solid

supercritical fluid

For molecules, atoms, or ions with the same mass, which of the following force typically is the strongest intermolecular interaction?

Answers:

ion dipole

hydrogen bonding

dipole dipole

dispersion

ion-induced dipole

The temperature at point b in the phase diagram below is the ________

Answers:

critical point.

triple point.

transition point.

normal freezing point.

normal boiling point.

Which of the following polar compounds is likely to have the highest boiling point?

Answers:

CH3OCH3

CH3CH2OH

(CH3)2CO

H2CO CO

Which molecule has the largest dipole?

Answers:

methane (CH4)

ammonia (NH3)

sulfur trioxide (SO3)

carbon dioxide (CO2)

ethylene (C2H4)

Which molecule does not exhibit hydrogen bonding?

Answers:

HF

CH3NH2

CH3OH

(CH3)3N

CH3CH2OH

The temperature at point a in the phase diagram below is the ________

Answers:

critical point.

triple point.

transition point.

normal freezing point.

normal boiling point.

Which of the following diagrams best shows a set of polar molecules interacting through dipole–dipole interactions?

Based on their boiling points, which of the following compounds has the largest dipole dipole interaction?

Answers:

propane (231 K)

dimethyl ether (248 K)

acetonitrile (355 K)

methyl chloride (249 K)

butane (135 K)

Which of the following compounds is capable of dipole–dipole interactions?

Answers:

CH₄

CO₂

H₂CO

SF₆

NH₄ ⁺

The relative energies (strengths) of the intermolecular forces between four different substances are shown in the figure below. Which substance has the highest boiling point?

Answers:

a

b

c

d

ndicate which of the following nonpolar compounds will have the lowest boiling point.

Answers:

CCl4

CI4

CF4

CH4

CBr4

Which of the following compounds will not possess dipole dipole interactions between its molecules?

Answers:

CF4

NH3

H2S

CH2F2

CH3Cl

The relative energies (strengths) of the intermolecular forces between four different substances are shown in the figure below. Which substance has the lowest boiling point?

Answers:

a

b

c

d

Indicate which of the following pairs of compounds is most likely to be miscible.

Answers:

H2O and CH3CH2CH2CH3

Br2 and HI

HF and CCl4

CCl4 and Br2

CCl4 and NH3

When sodium chloride dissolves in water, how do the water molecules orient around the ions?

Answers:

Water molecules are randomly oriented around the ions.

The hydrogen atoms point toward both the sodium and the chloride.

The oxygen atoms point toward both the sodium and the chloride.

Around sodium the hydrogen atoms point toward the sodium, and around chloride the oxygen atoms point toward the chloride.

Around sodium the oxygen atoms point toward the sodium, and around chloride the hydrogen atoms point toward the chloride.

Which statement about a hydrogen bond is not correct?

Answers:

"Hydrogen bonds involve hydrogen bonded to carbon, nitrogen, oxygen, or fluorine."

"In a hydrogen bond, the hydrogen atom on one molecule is attracted to unpaired electrons associated with nitrogen, oxygen, or fluorine on another molecule."

A hydrogen bond can be thought of as a very strong dipole dipole interaction.

The presence of hydrogen bonds leads to anomalously high boiling points for liquids.

Hydrogen bonds stabilize the double helix structure of DNA.

Which statement about vapor pressure of a pure liquid is not correct?

Answers:

The vapor pressure is the pressure of the gas at a given temperature in equilibrium with its liquid phase.

The temperature at which the vapor pressure equals 760 torr is called the normal boiling point of the substance.

The vapor pressure increases with increasing temperature.

The vapor pressure increases with increasing surface area of the liquid.

Substances with weak intermolecular forces have high vapor pressures at a given temperature.

Viscosity is a measure of a substance s ________

Answers:

ability to resist changes in its surface area.

surface tension.

resistance to flow.

compressibility. color.

At critical point ________________

Answers:

all the liquid has evaporated.

the densities of the solid and the liquid are the same.

the densities of the solid and the gas are the same.

the densities of the gas and the liquid are the same.

a critical mass has been reached.

Which of the following molecules has the highest boiling point?

Answers:

CH4

SiH4

SnH4

GeH4

H2

Which statement about vapor pressure of a pure liquid is not correct?

Answers:

The vapor pressure is the pressure of the gas at a given temperature in equilibrium with its liquid phase.

The temperature at which the vapor pressure equals 760 torr is called the normal boiling point of the substance.

The vapor pressure increases with increasing temperature.

The vapor pressure increases with increasing surface area of the liquid.

Substances with weak intermolecular forces have high vapor pressures at a given temperature.

he temperature at point b in the phase diagram below is the ________

Answers:

critical point.

triple point.

transition point.

normal freezing point.

normal boiling point.

The vapor pressure of a liquid will increase if ________

Answers:

the temperature is increased.

the volume available to the gas phase is increased.

the volume of the liquid phase is increased.

the liquid is stirred.

the liquid is put in a container with a larger surface area.

The phase diagram for carbon dioxide is shown below. What is the phase that exists at room temperature and pressure (22^oC, 1 atm)?

Answers:

gas

liquid

solid

supercritical fluid

Which of the following molecules will have the least interaction with a Li+ ion?

Answers:

water (H2O)

ethanol (CH3CH2OH)

chloroform (CHCl3)

ammonia (NH3)

pentane (C5H12)

Of all the noble gases, ________ has the weakest intermolecular force and hence the lowest boiling point.

Answers:

He

Ne

Ar

Kr

Xe

Which is the dominant interaction between acetone molecules, (CH₃)₂CO?

Answers:

ion ion

ion dipole

dipole dipole

hydrogen bonding

dispersion or London forces

Normal boiling points of branched alkane hydrocarbons generally are lower than for straight-chain hydrocarbons of the same molar mass because the straight-chain hydrocarbons ________

Answers:

have stronger dipole dipole interactions.

have many more electrons.

have more C H bonds.

have a larger surface area and come in closer contact with each other.

react with each other to form long chains.

Which of the following non-polar molecules will have the highest boiling point?

Answers:

CO2

C6H6 (benzene)

C6F6 (hexafluorobenzene)

C2H2

CF4

Which of the following molecules has the highest boiling point?

Answers:

CH4

SiH4

SnH4

GeH4

H2

Which is the dominant interaction between oxygen and nitrogen molecules in air?

Answers:

ion ion

ion dipole

dipole dipole

hydrogen bonding

dispersion or London forces

Gasoline is primarily a mixture of hydrocarbons and is sold with an octane rating that is based on a comparison with the combustion properties of isooctane. Gasoline usually contains an isomer of isooctane called tetramethylbutane (C8H18), which has an enthalpy of vaporization of 43.3 kJ/mol and a boiling point of 106.5°C. Determine the vapor pressure of tetramethylbutane on a very hot summer day when the temperature is 38°C.

Answers:

80.0 torr

36.7 torr

67.8 torr

47.9 torr

89.3 torr

Which of the following compounds will not possess dipole dipole interactions between its molecules?

Answers:

CF4

NH3

H2S

CH2F2

CH3Cl

Which of the following substances is a solid at 25°C and 1 atm?

The smell of fresh-cut pine is due in part to a cyclic alkene called pinene. A graph of the natural logarithm of the vapor pressure of pinene vs. 1/temperature produces a straight line with a slope of -4936.37 K. What is the enthalpy of vaporization of pinene?

Answers:

+397 kJ/mol

39.7 kJ/mol

+39.7 kJ/mol

- 41.0 kJ/mol

+41.0 kJ/mol

Which of the following compounds is capable of hydrogen bonding?Which of the following compounds is capable of hydrogen bonding?Answers:

CH3OCH3

CH3COCH3

CH3CH2OH

H2CO

CH3F

In which of the following diagrams are the cohesive interactions between molecules in the liquid greater than the adhesive forces between the liquid and the walls of the tube?

Answers:

a

b

c

d

Which of the following polar compounds is likely to have the highest boiling point?

Answers:

CH3OCH3

CH3CH2OH

(CH3)2CO

H2CO

CO

What does the line indicated by the arrow in the following phase diagram represent?

Answers:

solid–liquid boundary

solid–gas boundary

liquid–gas boundary

triple point

solid–solid boundary

Based on their boiling points, which of the following compounds has the largest dipole dipole interaction?

Answers:

propane (231 K)

dimethyl ether (248 K)

acetonitrile (355 K)

methyl chloride (249 K)

butane (135 K)

Which type of intermolecular interaction exists for all compounds?Answers:

ion ion

dipole dipole

dispersion

hydrogen bonding

dipole-induced dipole

When sodium chloride dissolves in water, how do the water molecules orient around the ions?

Answers:

Water molecules are randomly oriented around the ions.

The hydrogen atoms point toward both the sodium and the chloride.

The oxygen atoms point toward both the sodium and the chloride.

Around sodium the hydrogen atoms point toward the sodium, and around chloride the oxygen atoms point toward the chloride.

Around sodium the oxygen atoms point toward the sodium, and around chloride the hydrogen atoms point toward the chloride.

Of all the noble gases, ________ has the weakest intermolecular force and hence the lowest boiling point.

Answers:

He

Ne

Ar

Kr

Xe

Which of the substances a–d in the following figure has the weakest intermolecular forces?

a

b

c

d

Which intermolecular force is caused by an instantaneous dipole generated by close contact with other atoms or molecules?

Answers:

ion ion

forces ion

dipole forces

hydrogen bonding

dipole dipole

forces dispersion forces

The relative energies (strengths) of the intermolecular forces between four different substances are shown in the figure below. Which substance has the lowest boiling point?

a

b

c

d

Which of the following diagrams best shows a set of polar molecules interacting through dipole–dipole interactions?

What does the line indicated by the arrow in the following phase diagram represent?

Answers:

solid–liquid boundary

solid–gas boundary

liquid–gas boundary

triple point

solid–solid boundary

Which alkane compound has the lowest boiling point?

Answers:

C4H10

C5H12

C6H14

C7H16

C8H18