Deck 10: Intermolecular Forces: The Uniqueness of Water

Question 1

Ion-dipole forces always require________

A)an ion and a water molecule.
B)a cation and a water molecule.
C)an anion and a polar molecule.
D)an ion and a polar molecule.
E)a polar and a nonpolar molecule.

Answer 1

an ion and a polar molecule.

Question 2

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

A)HBr
B)CO₂
C)PH₃
D)NO
E)SCl₂

Answer 2

CO₂

Question 3

Which of the following compounds will have the strongest dipole-dipole interactions between its molecules?

A)CF₄
B)CH₄
C)CH₃F
D)CH₂F₂
E)CH₃Cl

Answer 3

CH₂F₂

Question 4

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

A)water (H₂O)
B)ethanol (CH₃CH₂OH)
C)chloroform (CHCl₃)
D)ammonia (NH₃)
E)pentane (C₅H₁₂)

Question 5

For a molecule to exhibit dipole-dipole interactions, it must ________

A)have a temporary dipole moment.
B)have a hydrogen bound to an oxygen, nitrogen, or fluorine.
C)have a permanent dipole moment.
D)be an ion.
E)have 3 or more atoms.

Question 6

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

A)CH₃OCH₃
B)CH₃CH₂OH
C)(CH₃)₂CO
D)H₂CO
E)CO

Question 7

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

A)Water molecules are randomly oriented around the ions.
B)The hydrogen atoms point toward both the sodium and the chloride.
C)The oxygen atoms point toward both the sodium and the chloride.
D)Around sodium the hydrogen atoms point toward the sodium, and around chloride the oxygen atoms point toward the chloride.
E)Around sodium the oxygen atoms point toward the sodium, and around chloride the hydrogen atoms point toward the chloride.

Question 8

Which molecule has the largest dipole?

A)fluorine gas (F₂)
B)dihydrogen gas (H₂)
C)dinitrogen gas (N₂)
D)chlorine monofluoride gas (ClF)
E)carbon dioxide gas (CO₂)

Question 9

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

A)propane (231 K)
B)dimethyl ether (248 K)
C)acetonitrile (355 K)
D)methyl chloride (249 K)
E)butane (135 K)

Question 10

Which statement about a hydrogen bond is not correct?

A)Hydrogen bonds involve hydrogen bonded to carbon, nitrogen, oxygen, or fluorine.
B)In a hydrogen bond, the hydrogen atom on one molecule is attracted to unpaired electrons associated with nitrogen, oxygen, or fluorine on another molecule.
C)A hydrogen bond can be thought of as a very strong dipole-dipole interaction.
D)The presence of hydrogen bonds leads to anomalously high boiling points for liquids.
E)Hydrogen bonds stabilize the double helix structure of DNA.

Question 11

Which molecule does not exhibit hydrogen bonding?

A)HF
B)CH₃NH₂
C)CH₃OH
D)(CH₃)₃N
E)CH₃CH₂OH

Question 12

Which of the following compounds is not capable of hydrogen bonding?

A)HF
B)CH₃OH
C)CH₃F
D)CH₃COOH
E)(CH₃)₂NH

Question 13

When potassium bromide dissolves in water, which picture best represents the solution?

A)
B)
C)
D)

Question 14

A hydration sphere forms around an ion in aqueous solution due to ________

A)ion-dipole interactions.
B)ion-hydrogen-bonding interactions.
C)dispersion forces.
D)dipole-dipole interactions.
E)ion-induced dipole interactions.

Question 15

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

A)CH₄
B)CO₂
C)H₂CO
D)SF₆
E)NH₄⁺

Question 16

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

A)
B)
C)
D)

Question 17

Which molecule has the largest dipole?

A)methane (CH₄)
B)ammonia (NH₃)
C)sulfur trioxide (SO₃)
D)carbon dioxide (CO₂)
E)ethylene (C₂H₄)

Question 18

Dipole-dipole interactions typically are not as strong as ion-dipole interactions because ________

A)ion-dipole interactions involve partial charges caused by the equal sharing of electrons by atoms forming a bond.
B)dipole-dipole interactions involve the complete transfer of charge between atoms.
C)ion-dipole interactions only involve the partial transfer of charge between atoms.
D)ion-dipole interactions always involve water.
E)dipole-dipole interactions only involve partial charges caused by unequal sharing of electrons by atoms forming a bond.

Question 19

Which of the following compounds is capable of hydrogen bonding?

A)(CH₃)₃N
B)CH₃CH₂NHCH₃
C)CH₃CH₂CH₃
D)CH₃COCH₃
E)H₂CO

Question 20

Which of the following solvents will involve ion-dipole interactions with Na⁺?

A)benzene (C₆H₆)
B)carbon tetrachloride (CCl₄)
C)chloroform (CHCl₃)
D)cyclohexane (C₆H₁₂)
E)pentane (C₅H₁₂)

Question 21

Polarizability refers to ________

A)the ease with which the electron cloud of an atom or molecule can be distorted.
B)the magnitude of the dipole moment of a molecule.
C)the ease with which a hydrogen bond can form.
D)the perturbation in electron density because of hydrogen bonding.
E)the ability to transmit polarized light.

Question 22

A substance that is ________ will be insoluble in water, but a substance that is ________ will be soluble in water.

A)hydrophobic; immiscible
B)immiscible; hydrophobic
C)hydrophilic; miscible
D)hydrophobic; hydrophilic
E)miscible; immiscible

Question 23

Arrange the following compounds in order of increasing dispersion interactions: CCl₄, CH₄, C₃H₈.

A)CH₄< C₃H₈ < CCl₄
B)CCl₄ < CH₄ < C₃H₈
C)C₃H₈ < CH₄ < CCl₄
D)CCl₄ < C₃H₈ < CH₄
E)CH₄ < CCl₄ < C₃H₈

Question 24

Indicate which of the following molecules exhibits the greatest dispersion forces.

A)CH₃CH₃
B)CH₃CH₂CH₃
C)C₂H₂
D)CH₄
E)CH₃CH₂CH₂CH₃

Question 25

The solubility of a compound is determined by ________

A)solute-solvent interactions.
B)solute-solute interactions.
C)solvent-solvent interactions.
D)the change in entropy.
E)all of the items listed.

Question 26

Which of the following representations best shows the formation of an instantaneous dipole moment between two nonpolar molecules?

A)
B)
C)
D)

Question 27

Hydrophilic substances ________

A)are immiscible in water.
B)are insoluble in water.
C)are soluble in water.
D)are hydrated.
E)generally do not hydrogen bond.

Question 28

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

A)CCl₄
B)CI₄
C)CF₄
D)CH₄
E)CBr₄

Question 29

Of all the noble gases, ________ has the strongest intermolecular force and hence the highest boiling point.

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

Question 30

The structure of an unsaturated phospholipid is shown below. Which region of the molecule is most hydrophilic?

A)I
B)II
C)III
D)IV
E)All regions are equally hydrophilic.

Question 31

At ambient temperature, F₂ and Cl₂ are both gases while Br₂ is a liquid and I₂ is a solid. This is due to ________

A)dipole-dipole forces increasing with increasing molecular weight.
B)dispersion forces increasing with increasing molecular weight.
C)molecule polarity increasing with increasing molecular weight.
D)both dispersion and polarity increasing with increasing molecular weight.
E)ion-dipole forces increasing with increasing molecular weight.

Question 32

Which of the following nonpolar molecules will have the highest boiling point?

A)CO₂
B)C₆H₆ (benzene)
C)C₆F₆ (hexafluorobenzene)
D)C₂H₂
E)CF₄

Question 33

A solute is most likely to be highly soluble in a solvent if the solute is ________ and the solvent is ________.

A)nonpolar; ionic
B)polar; nonpolar
C)polar; polar
D)nonpolar; polar
E)ionic; nonpolar

Question 34

Which of the following molecules has the highest boiling point?

A)CH₄
B)SiH₄
C)SnH₄
D)GeH₄
E)H₂

Question 35

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

A)ion-ion forces
B)ion-dipole forces
C)hydrogen bonding
D)dipole-dipole forces
E)dispersion forces

Question 36

Dispersion forces are due to ________

A)permanent dipoles.
B)temporary dipoles.
C)hydrogen bonding.
D)ionic interactions.
E)protons.

Question 37

When two liquids mix completely in all proportions, they are ________

A)soluble.
B)miscible.
C)insoluble.
D)solvated.
E)ubiquitous.

Question 38

Which best describes the intermolecular forces present in NH₃?

A)dispersion forces only
B)hydrogen bonding and dispersion forces
C)dipole-dipole, hydrogen bonding, and dispersion forces
D)dipole-dipole forces only
E)ion-dipole and dispersion forces

Question 39

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

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

Question 40

Molecular nitrogen (N₂) interacts with water and is sparingly soluble in water due to ________

A)dispersion forces.
B)dipole-induced dipole forces.
C)ion-dipole forces.
D)hydrogen bonding.
E)dipole-dipole forces.

Question 41

The solubility of any gas in a liquid can always be increased by ________

A)increasing the temperature.
B)using a solvent that can form hydrogen bonds.
C)using a solvent that is nonpolar.
D)decreasing the pressure of the gas above the solvent.
E)increasing the pressure of the gas above the solvent.

Question 42

If water contains about 42 mg of oxygen per liter at 20 ^$\circ$ C and 1.0 atm, what would be the value of Henry's law constant for oxygen dissolving in water? The mole fraction of oxygen in air is 0.21.

A)0.25 mol/(L atm)
B)1.3 10³ mol/(L atm)
C)1.9 10^-2 mol/(L atm)
D)6.3 10^-3 mol/(L atm)
E)0.010 mol/(L atm)

Question 43

Which of the following gases do you expect to be least soluble in a polar solvent?

A)OCS
B)He
C)NO
D)NH₃
E)CO

Question 44

Which of the following compounds would you most appropriately call hydrophobic?

A)CH₄
B)H₂CO
C)CO
D)HCl
E)NaCl

Question 45

The concept "like dissolves like" explains why

A)I₂ is more soluble in CCl₄ than water.
B)MgSO₄ is more soluble in CCl₄ than water.
C)CO gas is more soluble in CCl₄ than water.
D)CCl₄ is soluble in water.
E)CH₄ is more soluble in water than CCl₄.

Question 46

Which of the following compounds would be most soluble in carbon tetrachloride, CCl₄?

A)H₂O
B)CH₃OH
C)NH₃
D)C₆H₆
E)HCl

Question 47

Of the two compounds shown below, one is slightly soluble in water and the other is insoluble in water. Identify the slightly soluble compound and explain why it is soluble in water.

A)I because it can form hydrogen bonds with water at each end of the molecule.
B)I because it has stronger dispersion interactions with water.
C)II because it has stronger dipole-dipole interactions with water.
D)II because it has stronger dispersion interactions with water.
E)I because it is nonpolar.

Question 48

Which of the following compounds do you expect to be most soluble in water?

A)CO₂
B)CCl₄
C)O₂
D)SiO₂
E)NH₃

Question 49

Which of the following compounds would be most soluble in water?

A)CH₄
B)H₂
C)N₂
D)C₂H₄
E)CH₃OH

Question 50

Which of the following statements does not correctly characterize the rate of evaporation of a liquid?
I. Increases with increasing temperature because molecules have higher kinetic energies.
II. Increases with increasing surface area of the liquid because more molecules are located at the surface.
III. Increases with stronger intermolecular forces because molecules in the liquid repel each other more.

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

Question 51

The carbon dioxide pressure in a bottle of champagne is about 6 atm. At this pressure about 0.45 g of carbon dioxide dissolves in 100 mL of champagne. How much carbon dioxide remains dissolved in 100 mL after the bottle is opened? The partial pressure of carbon dioxide then is 6.0 10^-4 atm.

A)0.45 g
B)3.8 10^-3 g
C)1.7 10^-6 g
D)9.0 10^-4 g
E)4.5 10^-5 g

Question 52

Which alcohol should be most soluble in a nonpolar solvent such as hexane, C₆H₁₄?

A)CH₃OH
B)CH₃CH₂OH
C)CH₃CH₂CH₂OH
D)CH₃CH₂CH₂CH₂OH
E)CH₃CH₂CH₂CH₂CH₂OH

Question 53

The pressure of carbon dioxide in a beer bottle is about 2 atm. At this pressure about 0.15 g of carbon dioxide dissolves in 100 mL of beer. How much carbon dioxide remains dissolved in 100 mL after the bottle is opened? The partial pressure of carbon dioxide is 2.0 10^-4 atm.

A)0.15 g
B)3.8 10^-3 g
C)6.0 10^-5 g
D)3.0 10^-4 g
E)1.5 10^-5 g

Question 54

Which of the following gases do you expect to be most soluble in water?

A)CO₂
B)Ar
C)O₂
D)N₂
E)NH₃

Question 55

Henry's law constant (mol/L · atm) for oxygen dissolving in blood is 3.74 $\times$ 10^-2 mol/L · atm at body temperature, 37 ^$\circ$ C. Calculate the molar concentration of oxygen in blood for an alpine climber where the atmospheric pressure is 0.45 atm. The mole fraction of oxygen in air is 0.209.

A)7.8 10^-3 M
B)3.5 10^-3 M
C)2.3 10^-2 M
D)1.3 10^-2 M
E)0.11 M

Question 56

Which of the following pairs of compounds is most likely to be immiscible?

A)Br₂ and C₆H₆
B)H₂O and CH₃CH₂OH
C)CCl₄ and H₂CO
D)CH₃OH and CH₃CH₂OH
E)H₂O and NH₃

Question 57

The pressure inside a bottle of carbonated beverage decreases when it is cooled in a refrigerator. What is the main reason for this change?

A)The solubility of carbon dioxide is higher at the lower temperature.
B)Some carbon dioxide condenses to form a liquid phase.
C)The volume of the vapor contracts.
D)The volume of the liquid contracts.
E)The volume of the bottle contracts.

Question 58

Air (consisting mostly of nitrogen (N₂), oxygen (O₂), and argon (Ar)) dissolves in water due to ________

A)dispersion forces.
B)dipole-induced dipole forces.
C)ion-dipole forces.
D)hydrogen bonding.
E)dipole-dipole forces.

Question 59

The Henry's law constant (mol/L · atm) for carbon dioxide dissolving in water is 3.50 $\times$ 10^-2 mol/(L atm) at 20 ^$\circ$ C. Calculate the molar concentration of carbon dioxide in a soda can where the air pressure is 2.45 atm. The mole fraction of carbon dioxide in air is 0.0397.

A)1.4 10^-3 M
B)3.4 10^-3 M
C)2.7 10^-2 M
D)8.2 10^-2 M
E)8.6 10^-2 M

Question 60

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

A)H₂O and CH₃CH₂CH₂CH₃
B)Br₂ and HI
C)HF and CCl₄
D)CCl₄ and Br₂
E)CCl₄ and NH₃

Question 61

Which alkane compound has the highest boiling point?

A)C₄H₁₀
B)C₅H₁₂
C)C₆H₁₄
D)C₇H₁₆
E)C₈H₁₈

Question 62

Which plot shown below would be useful in determining the enthalpy of vaporization of a substance?

A)
B)
C)
D)
E)

Question 63

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 4,936.37 K. What is the enthalpy of vaporization of pinene?

A)( 397 kJ/mol)
B)( 39.7 kJ/mol)
C)( 39.7 kJ/mol)
D)( 41.0 kJ/mol)
E)( 41.0 kJ/mol)

Question 64

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 ^$\circ$ C. Determine the vapor pressure of tetramethylbutane on a very hot summer day when the temperature is 38 ^$\circ$ C.

A)80.0 torr
B)36.7 torr
C)67.8 torr
D)47.9 torr
E)89.3 torr

Question 65

If the same liquid is present in each of the containers shown below, choose the solution with the highest rate of evaporation. Assume each container is full and has equal volume and only the top of the container is open.

A)I
B)II
C)III
D)IV
E)All have equal evaporation rates.

Question 66

Which of the following statements does not correctly identify a factor that affects the boiling point of a pure substance?
I. vapor pressure of the liquid
II. strength of intermolecular forces
III. enthalpy of vaporization
IV. surface area of the liquid

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

Question 67

A phase diagram shows the states of a substance as a function of ________ and ________.

A)pressure; volume
B)volume; temperature
C)pressure; temperature
D)concentration; temperature
E)density; pressure

Question 68

Which of the following statements correctly characterizes the rate of evaporation of a liquid?
I. Increases with increasing temperature because molecules have higher kinetic energies.
II. Increases with increasing surface area of the liquid because more molecules are located at the surface.
III. Decreases with stronger intermolecular forces because molecules are less able to escape from the surface of the liquid.

A)I only
B)II only
C)III only
D)I and II only
E)all three: I, II, and III

Question 69

Which alkane compound has the lowest boiling point?

A)C₄H₁₀
B)C₅H₁₂
C)C₆H₁₄
D)C₇H₁₆
E)C₈H₁₈

Question 70

Which alkane compound has the highest vapor pressure?

A)C₄H₁₀
B)C₅H₁₂
C)C₆H₁₄
D)C₇H₁₆
E)C₈H₁₈

Question 71

The vapor pressure of a liquid increases with increasing temperature because ________

A)more molecules can escape from the liquid because their average kinetic energy is greater.
B)the number of gas molecules above the liquid does not change but their average kinetic energy increases.
C)the molecules in the liquid move faster and exert a greater pressure.
D)the ideal gas law states that the pressure is proportional to the temperature.
E)molecules interact less strongly at higher temperatures.

Question 72

Gasoline is primarily a mixture of hydrocarbons and is sold with an octane rating that is based on a comparison with the properties of isooctane (C₈H₁₈), which has an enthalpy of vaporization of 35.8 kJ/mol and a boiling point of 98.2 ^$\circ$ C. Determine the vapor pressure of isooctane on a very hot summer day when the temperature is 38 ^$\circ$ C.

A)80.0 torr
B)36.7 torr
C)67.8 torr
D)47.9 torr
E)89.3 torr

Question 73

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

A)solid-liquid boundary
B)solid-gas boundary
C)liquid-gas boundary
D)triple point
E)solid-solid boundary

Question 74

Portable lanterns and stoves used for camping often use a mixture of hydrocarbons for fuel. One such hydrocarbon is an alkane called n-pentane. These lanterns and stoves are often difficult to light on a cold day because the fuel has a low vapor pressure at low temperatures. Determine the vapor pressure of n-pentane on a night when the temperature is 0.0 ^$\circ$ C. The enthalpy of vaporization of n-pentane is 27.6 kJ/mol, and its boiling point is 36.0 ^$\circ$ C.

A)228 torr
B)367 torr
C)184 torr
D)479 torr
E)209 torr

Question 75

The aroma from almonds and cherries is due in part to a compound called benzaldehyde. A graph of the natural logarithm of the vapor pressure of benzaldehyde vs. 1/temperature produces a straight line with a slope of 5,870.99 K. What is the enthalpy of vaporization of benzaldehyde?

A)( 473 kJ/mol)
B)( 47.3 kJ/mol)
C)( 47.3 kJ/mol)
D)( 48.8 kJ/mol)
E)( 48.8 kJ/mol)

Question 76

The vapor pressure of a liquid will increase if ________

A)the temperature is increased.
B)the volume available to the gas phase is increased.
C)the volume of the liquid phase is increased.
D)the liquid is stirred.
E)the liquid is put in a container with a larger surface area.

Question 77

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

A)The vapor pressure is the pressure of the gas at a given temperature in equilibrium with its liquid phase.
B)The temperature at which the vapor pressure equals 760 torr is called the normal boiling point of the substance.
C)The vapor pressure increases with increasing temperature.
D)The vapor pressure increases with increasing surface area of the liquid.
E)Substances with weak intermolecular forces have high vapor pressures at a given temperature.

Question 78

Which alkane compound has the lowest vapor pressure?

A)C₄H₁₀
B)C₅H₁₂
C)C₆H₁₄
D)C₇H₁₆
E)C₈H₁₈

Question 79

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

A)solid-liquid boundary
B)solid-gas boundary
C)liquid-gas boundary
D)triple point
E)solid-solid boundary

Question 80

Which one of the following substances would you predict to have the highest vapor pressure at a given temperature? In these line drawings, a carbon is implicit at the end of a line (bond) or where two or more lines come together. Carbon requires four bonds, so any missing bonds are implicitly bonds to hydrogen atoms.

A)
B)
C)
D)
E)