Deck 10: Forces Between Ions and Molecules

Question 1

Dispersion forces are due to __________

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

Answer 1

temporary dipoles.

Question 2

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.

Answer 2

dipole-dipole interactions only involve partial charges caused by unequal sharing of electrons by atoms forming a bond.

Question 3

Which of the following compounds is capable of hydrogen bonding?

A) CH₃OCH₃
B) CH₃COCH₃
C) CH₃CH₂OH
D) H₂CO
E) CH₃F

Answer 3

CH₃CH₂OH

Question 4

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 5

Which of the following will require the greatest energy input to separate the ions?

A) MgI₂
B) MgF₂
C) MgCl₂
D) MgBr₂
E) NaCl

Question 6

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 7

For molecules or atoms with the same mass, which of the following is the weakest intermolecular interaction?

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

Question 8

Ion interaction energies are determined by Coulomb's law: Determine the energy of potassium chloride if the radius of the potassium ion is 133 pm and that of the chloride ion is 181 pm.

A) -7.36  10^-19 J
B) -7.36  10^-22 J
C) 7.36  10^-19 J
D) 1.74  10^-18 J
E) -7.36  10^-25 J

Question 9

Coulomb's law states that the energy of attraction between ions depends __________

A) only on the charge of the cation.
B) only on the charge of the anion.
C) directly on the distance between the ions.
D) on the charges of both ions.
E) on the temperature.

Question 10

Arrange the three compounds sodium chloride, magnesium chloride, and aluminum chloride in order of increasing melting point.

A) NaCl < MgCl₂ < AlCl₃
B) MgCl₂ < NaCl < AlCl₃
C) AlCl₃ < MgCl₂ < NaCl
D) AlCl₃ < NaCl < MgCl₂
E) NaCl < AlCl₃ < MgCl₂

Question 11

Predict which of the following compounds has the highest melting point.

A) NaF
B) KCl
C) RbCl
D) BeF₂
E) NaCl

Question 12

Which of the following requires the smallest energy to separate the ions?

A) CaF₂
B) KF
C) NaF
D) MgF₂
E) LiCl

Question 13

The interaction energy of LiF is -1.14  10^-18 J. What is the distance between the Li⁺ and F^- ions?

A) 203 nm
B) 203 pm
C) 0.203 pm
D) 494 pm
E) 302 pm

Question 14

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 15

Which of the following will have the largest cation-anion attraction?

A) NaF
B) NaCl
C) NaBr
D) NaI
E) CsCl

Question 16

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 17

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

A) CH₄
B) CO₂
C) H₂CO
D) SF₆
E) NH₄⁺

Question 18

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 19

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

A)
B)
C)
D)

Question 20

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.

Question 21

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 22

Given the van der Waals a constant values for the following gases, which gas has the lowest boiling point?

A) N₂ a = 1.35 L² · atm/mol²
B) O₂ a = 1.36 L² · atm/mol²
C) NH₃ a = 4.25 L² · atm/mol²
D) CH₄ a = 2.27 L² · atm/mol²
E) SO₂ a = 6.71 L² · atm/mol²

Question 23

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 24

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 25

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

A) CH₄
B) H₂CO
C) CO
D) HCl
E) NaCl

Question 26

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

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

Question 27

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

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

Question 28

Which of the following gases would you expect to have the largest van der Waals a constant value?

A) Kr
B) N₂
C) O₂
D) H₂
E) Ne

Question 29

Which of the following compounds would you expect to be a solid at room temperature and atmospheric pressure?

A) C₂H₄ (an alkene)
B) HCl (an acid)
C) CH₃CH₂CH₂CH₃ (an alkane)
D) C₁₀H₈ (an aromatic hydrocarbon)
E) C₆H₆ (an aromatic hydrocarbon)

Question 30

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

A) CCl₄
B) CI₄
C) CF₄
D) CH₄
E) CBr₄

Question 31

Which of the following substances would you expect to have the largest van der Waals a constant value?

A) CO₂
B) F₂
C) CH₃CH₂OH
D) CH₃Cl
E) N₂

Question 32

Given the van der Waals a constant values for the following gases, which gas has the greatest intermolecular forces?

A) N₂ a = 1.35 L² · atm/mol²
B) O₂ a = 1.36 L² · atm/mol²
C) NH₃ a = 4.25 L² · atm/mol²
D) CH₄ a = 2.27 L² · atm/mol²
E) SO₂ a = 6.71 L² · atm/mol²

Question 33

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 34

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

A) H₂O
B) CH₃OH
C) NH₃
D) C₆H₆
E) HCl

Question 35

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 36

Under similar conditions, which of the following gases will behave less like an ideal gas than the others?

A) NH₃
B) HCl
C) CH₄
D) H₂
E) O₂

Question 37

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

A)
B)
C)
D)

Question 38

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

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

Question 39

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 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 resistance of a liquid to an increase in its surface area is __________

A) surface tension.
B) viscosity.
C) capillary action.
D) a meniscus.
E) impossible.

Question 42

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

A)
B)
C)
D)

Question 43

The density of water decreases as it is cooled from 4.0°C to freezing because __________

A) water molecules decrease in size as they cool because energy is released.
B) a network of hydrogen bonds between water molecules is formed.
C) water molecules become more rigid as they cool.
D) hydrogen bonds in liquid water are longer than they are in ice.
E) all substances contract just before freezing.

Question 44

The relative energies (strengths) of the intermolecular forces present in each of four different pure gases are shown in the figure below. Which gas will show the smallest deviation from ideal gas behavior?

A) a
B) b
C) c
D) d

Question 45

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) a
B) b
C) c
D) d

Question 46

The relative energies (strengths) of the intermolecular forces present in each of four different pure substances are shown in the figure below. Which substance is most likely to be a gas at room temperature?

A) a
B) b
C) c
D) d

Question 47

Viscosity is a measure of a substance's __________

A) ability to resist changes in its surface area.
B) surface tension.
C) resistance to flow.
D) compressibility.
E) color.

Question 48

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

A) a
B) b
C) c
D) d

Question 49

Which of the following substances has a solid whose freezing point will decrease with increasing pressure?

A)
B)
C)
D)

Question 50

At the triple point of a substance, __________

A) three phases are present in equilibrium.
B) the solid sublimes.
C) the gas condenses to a liquid.
D) solid and liquid are in equilibrium.
E) only one phase appears to be present.

Question 51

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

A) s- boundary
B) s-g boundary
C) -g boundary
D) triple point
E) s-s boundary

Question 52

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?

A) a
B) b
C) c
D) d

Question 53

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?

A) a
B) b
C) c
D) d

Question 54

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

A) a
B) b
C) c
D) d

Question 55

At the critical point, __________

A) all the liquid has evaporated.
B) the densities of the solid and liquid are the same.
C) the densities of the solid and the gas are the same.
D) the densities of the gas and the liquid are the same.
E) a critical mass has been reached.

Question 56

Which of the following substances has a solid that is less dense than the liquid?

A)
B)
C)
D)

Question 57

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 58

At the point marked with a dot on the phase diagram, the solid will __________

A) be indistinguishable from the gas.
B) boil.
C) melt.
D) sublime.
E) liquify.

Question 59

Consider the phase diagram for a substance shown here. The solid phase is ________ than the liquid phase.

A) more dense
B) less dense
C) more massive
D) less massive
E) hotter

Question 60

Water forms a concave meniscus in a glass tube because __________

A) the cohesive forces between water molecules are larger than the adhesive forces between water molecules and the glass wall.
B) the adhesive forces between water molecules and the glass wall are larger than the cohesive forces between water molecules.
C) water molecules form hydrogen bonds with each other.
D) water molecules repel each other.
E) the glass wall is wet.

Question 61

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)

Question 62

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

A) critical point.
B) triple point.
C) transition point.
D) normal freezing point.
E) normal boiling point.

Question 63

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 64

Which statement about the phase diagram below is not correct?

A) The critical point is not shown.
B) D is the normal boiling point.
C) The vapor pressure of the solid is zero below the triple point.
D) The normal melting point is at a lower temperature than the triple point.
E) E, F, and G label in that order the solid, liquid, and gas phases.

Question 65

The relative energies (strengths) of the intermolecular forces present in each of four different pure substances are shown in the figure below. Which substance is most likely to be a solid at room temperature?

A) a
B) b
C) c
D) d

Question 66

Point d in the phase diagram below is the __________

A) critical point.
B) triple point.
C) transition point.
D) normal freezing point.
E) normal boiling point.

Question 67

The boiling point of HBr is higher than that of HCl because HBr has __________ (The dipole moments are 1.08 D for HCl and 0.82 D for HBr.)

A) fewer electrons.
B) larger dispersion interactions.
C) hydrogen bonding.
D) larger dipole-dipole interactions.
E) more ionic character.

Question 68

Rank the following compounds in order of increasing attraction between their ions: KBr, SrBr₂, and CsBr.

A) CsBr < KBr < SrBr₂
B) SrBr₂ < CsBr < KBr
C) KBr < SrBr₂ < CsBr
D) CsBr < SrBr₂ < KBr
E) SrBr₂ < KBr < CsBr

Question 69

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

A) a
B) b
C) c
D) d

Question 70

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 71

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

A) critical point.
B) triple point.
C) transition point.
D) normal freezing point.
E) normal boiling point.

Question 72

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 73

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

Question 74

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 75

Which one of the following substances would you predict to have the highest boiling point? 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)

Question 76

Henry's law constant (mol/L · atm) for oxygen dissolving in blood is 3.74  10^-2 mol/L · atm at body temperature, 37°C. Calculate the molar concentration of oxygen in blood for a scuba diver where the air pressure is 2.0 atm. The mole fraction of oxygen in air is 0.209.

A) 7.8  10^-3 M
B) 2.7  10^-3 M
C) 1.5  10^-2 M
D) 1.3  10^-2 M
E) 0.11 M

Question 77

Henry's law constant (mol/L · atm) for oxygen dissolving in blood is 3.74  10^-2 mol/L · atm at body temperature, 37°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 78

Point c in the phase diagram below is the __________

A) critical point.
B) triple point.
C) transition point.
D) normal freezing point.
E) normal boiling point.

Question 79

Water contains about 42 mg of oxygen per liter at 20°C, and 1 atm. What is Henry's law constant (mol/L atm) for oxygen dissolving in water?

A) 0.25 mol/L · atm
B) 1.3  10^-3 mol/L · atm
C) 1.9  10^-2 mol/L · atm
D) 3.7  10^-2 mol/L · atm
E) 0.010 mol/L · atm

Question 80

Which type of intermolecular interaction exists for all compounds?

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