Deck 12: Intermolecular Forces and Liquids

Question 1

Which one of the following statements is $\underline{\text{false? }}$

A) All ions are hydrated in aqueous solution.
B) All cations are hydrated in aqueous solution.
C) All anions are hydrated in aqueous solution.
D) Hydration is generally highly endothermic for ionic compounds.
E) The heats of hydration of cations increases as their charge-to-radius ratios increase.

Answer 1

Hydration is generally highly endothermic for ionic compounds.

Question 2

Which of the following correctly describes the states of matter and intermolecular forces?
1)The change in volume that accompanies the conversion of a liquid to a gas can be very large.
2)The change in volume that accompanies the conversion of a liquid to a solid is small.
3)The forces of attraction between molecules in the liquid and solid state correlate with melting point,boiling point,and the energy of phase changes.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2 and 3

Answer 2

1,2 and 3

Question 3

Place the following cations in order from the lowest to the highest hydration enthalpy: K⁺,Ca²⁺,and Mg²⁺.

A) K⁺ < Ca²⁺ < Mg²⁺
B) Mg²⁺ < Ca²⁺ < K⁺
C) Ca²⁺ < K⁺ < Mg²⁺
D) Ca²⁺ < Mg²⁺ < K⁺
E) Mg²⁺ < K⁺ < Ca²⁺

Answer 3

K⁺ < Ca²⁺ < Mg²⁺

Question 4

Which of the following correctly describes the influence of intermolecular forces on the properties of matter?
1)Intermolecular forces determine the solubility of gases,liquids,and solids in various solvents.
2)Intermolecular forces are directly related to the energy required to accomplish phase changes.
3)Intermolecular forces do not influence the structure of molecules like DNA and proteins.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2 and 3

Question 5

Arrange HF,HCl,and HBr in order from lowest to highest boiling point.

A) HF < HCl < HBr
B) HF < HBr < HCl
C) HBr < HF < HCl
D) HBr < HCl < HF
E) HCl < HBr < HF

Question 6

Which of the following statements concerning the attraction of ions to polar molecules is/are CORRECT?
1)The energy of attraction between an ion and a polar molecule is inversely proportional to the square of the distance between the center of the ion and the oppositely charged pole of the dipole.
2)The higher the ion charge,the stronger the attraction between the ion and a polar molecule.
3)The greater the magnitude of the dipole,the greater the attraction between the ion and a polar molecule.

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3
E) 1,2,and 3

Question 7

Hydrogen bonding is present in all of the following molecular solids EXCEPT ____.

A) H₂SO₄ (dihydrogen sulfate)
B) CH₃OH (methanol)
C) CH₃OCH₃ (dimethyl ether)
D) HF (hydrogen fluoride)
E) CH₃CO₂H (acetic acid)

Question 8

Arrange H₂S,H₂Se,and H₂Te in order from lowest to highest boiling point.

A) H₂Te < H₂Se < H₂S
B) H₂S < H₂Se < H₂Te
C) H₂S < H₂Te < H₂Se
D) H₂Se < H₂Te < H₂S
E) H₂Te < H₂S < H₂Se

Question 9

A molecule will $\underline{\text{always }}$ be polar if it ___.

A) has polar bonds
B) contains both carbon and chlorine
C) consists of more than three atoms
D) is diatomic with different electronegativities
E) contains atoms with different electronegativities

Question 10

Which of the following molecules is expected to form hydrogen bonds in the pure liquid or solid phase: ethanol (CH₃CH₂OH),acetic acid (CH₃CO₂H),acetaldehyde (CH₃CHO),and dimethyl ether (CH₃OCH₃)?

A) ethanol only
B) acetaldehyde only
C) ethanol and acetic acid
D) acetaldehyde and dimethyl ether
E) ethanol and dimethyl ether

Question 11

The elements of group 5A,the nitrogen family,form compounds with hydrogen having the boiling points listed below:

SbH₃ -17°C,AsH₃ -55°C,PH₃ -87°C,NH₃ -33°C.

The first three compounds illustrate a trend where the boiling point decreases as the mass decreases; however,ammonia (NH₃)does not follow the trend because of ___.

A) dipole-dipole attraction
B) metallic bonding
C) hydrogen bonding
D) London dispersion forces
E) ionic bonding

Question 12

As pure molecular solids,which of the following exhibits dipole-dipole intermolecular forces: HBr,NBr₃,SBr₂,and CBr₄?

A) HBr only
B) CBr₄ only
C) HBr and SBr₂
D) NBr₃ and CBr₄
E) HBr,NBr₃,and SBr₂

Question 13

Which of the following strong electrolytes has the least negative hydration enthalpy?

A) NaCl
B) KCl
C) RbCl
D) CsCl
E) HCl

Question 14

Place the following cations in order from the most negative to the least negative hydration enthalpy: Cs⁺,Na⁺,and Rb⁺.

A) Cs⁺ < Rb⁺ < Na⁺
B) Cs⁺ < Na⁺ < Rb⁺
C) Na⁺ < Rb⁺ < Cs⁺
D) Na⁺ < Cs⁺ < Rb⁺
E) Rb⁺ < Na⁺ < Cs⁺

Question 15

As pure molecular solids,which of the following exhibits dipole-dipole intermolecular forces: PH₃,SO₃,HCl,and CO₂?

A) PH₃ only
B) HCl only
C) SO₃ and CO₂
D) PH₃ and HCl
E) SO₃,HCl,and CO₂

Question 16

Which of the following bonds can potentially contribute to the formation of a hydrogen bond in a solid or liquid?

A) Ge-H
B) P-H
C) N-H
D) Si-H
E) Cl-H

Question 17

When a water molecule forms a hydrogen bond with another water molecule,which atoms are involved in the interaction?

A) a hydrogen from one molecule and a hydrogen from the other molecule
B) a hydrogen from one molecule and an oxygen from the other molecule
C) an oxygen from one molecule and an oxygen from the other molecule
D) an oxygen and a hydrogen from the same molecule
E) two hydrogens from one molecule and one hydrogen from the other molecule

Question 18

Which one of the following sets of ions are listed in order of lowest to highest hydration energy?

A) H⁺ < Na⁺ < Mg²⁺
B) Mg²⁺ < Ca²⁺ < Ba²⁺
C) Mg²⁺ < Ba²⁺ < Ca²⁺
D) Ca²⁺ < K⁺ < Rb⁺
E) Rb⁺ < K⁺ < Ca²⁺

Question 19

Which one of the following molecules will exhibit dipole-dipole intermolecular forces as a pure liquid or solid?

A) CS₂
B) C₂H₂
C) CCl₄
D) F₂
E) PCl₃

Question 20

Which of the following statements best describes what happens when a small amount of solid rubidium bromide is dissolved in water?

A) The heat from the warm water melts the solid,making it a liquid.
B) Nothing happens,because rubidium bromide is insoluble in water.
C) The solid RbBr breaks apart into separate Rb and Br atoms by interacting with the water molecules.
D) The water molecules surround each ion in the solid RbBr,separating the Rb ions from the Br ions.
E) The solid undergoes a chemical change by reacting with the water.

Question 21

Which of the following substances will have the strongest intermolecular forces?

A) H₂S
B) CO
C) CH₃OH
D) HBr
E) Ar

Question 22

What intermolecular force(s)is/are present in solid NH₃?
1)induced dipole/induced dipole
2)dipole-dipole
3)hydrogen bonding

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1 and 3

Question 23

What is the $\underline{\text{ strongest }}$ intermolecular force present in solid NH₃?

A) London dispersion
B) hydrogen-bonding
C) dipole-dipole
D) ion-dipole

Question 24

Which of the following nonpolar molecules has the highest boiling point?

A) N₂
B) C₂H₄
C) F₂
D) O₂
E) CS₂

Question 25

Which of the following statements concerning induced dipole/induced dipole forces is/are CORRECT?
1)In general,induced dipole/induced dipole interactions decrease as the size of a molecule increases.
2)Induced dipole/induced dipole forces are the attractive forces in molecular solids consisting of nonpolar molecules.
3)Induced dipole/induced dipole forces exist in both polar and nonpolar molecular solids.

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3
E) 1,2,and 3

Question 26

For which of the following pure solids is it necessary to break covalent bonds to make a liquid or gas: C(graphite),CO₂(s),C₆₀(s),and C(diamond)?

A) C(graphite)only
B) CO₂(s)only
C) CO₂(s)and C₆₀(s)
D) C(graphite),C₆₀(s)and C(diamond)
E) C(graphite)and C(diamond)

Question 27

The molecules in solid PH₃ are attracted to each other by ___.

A) London dispersion forces
B) hydrogen-bonding
C) dipole-dipole interactions
D) London dispersion forces and dipole-dipole interactions
E) London dispersion forces and hydrogen-bonding

Question 28

What intermolecular force or bond is primarily responsible for the solubility of CH₃OH in water?

A) ion-dipole force
B) dipole-dipole force
C) ionic bonding
D) covalent bonding
E) hydrogen bonding

Question 29

List all the intermolecular forces present in pure acetone.

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

Question 30

Which of the following pure liquids is expected have the highest boiling point?

A) CO
B) NO
C) PH₃
D) AsH₃
E) ICl

Question 31

Which of the following compounds has a boiling point closest to that of argon?

A) F₂
B) Cl₂
C) HCl
D) NaF
E) HF

Question 32

Which of the following boils at the $\underline{\text{ highest }}$ temperature?

A) C₅H₁₂
B) C₆H₁₄
C) C₇H₁₆
D) C₈H₁₈
E) C₉H₂₀

Question 33

Arrange Cl₂,ICl,and Br₂ in order from lowest to highest boiling point.

A) Cl₂ < Br₂ < ICl
B) Cl₂ < ICl < Br₂
C) ICl < Cl₂ < Br₂
D) Br₂ < Cl₂ < ICl
E) Br₂ < ICl < Cl₂

Question 34

Which of the following has the $\underline{\text{ greatest }}$ boiling point?

A) Ne
B) N₂
C) Cl₂
D) I₂
E) F₂

Question 35

London dispersion forces are the only significant factor affecting boiling point for all the following except?

A) Ne
B) H₂SO₄
C) CF₄
D) Br₂
E) CH₄

Question 36

Which one of the following molecules has the lowest boiling point?

A) CH₄
B) CHCl₃
C) CH₂Cl₂
D) CH₃Cl
E) CCl₄

Question 37

Which of the following statements concerning intermolecular forces is/are CORRECT?
1)Dipole-dipole attractions occur in all molecules that contain polar bonds,regardless of whether the molecule has a dipole.
2)Induced dipole/induced dipole forces exist in all molecular solids.
3)Hydrogen bonding only occurs in all molecules containing OH bonds.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 38

Which intermolecular force or bond is responsible for the density of H₂O(s)being less than that of H₂O( )?

A) London dispersion forces
B) hydrogen bonding
C) ionic bonding
D) covalent bonding
E) dipole/induced dipole forces

Question 39

What intermolecular force or bond is primarily responsible for the solubility of oxygen (O₂)in water?

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

Question 40

As pure molecular solids,which of the following exhibit only induced dipole/induced dipole forces: CO₂,CH₂Cl₂,and SO₂?

A) CO₂ only
B) CH₂Cl₂ only
C) SO₂ only
D) CO₂ and CH₂Cl₂
E) CO₂ and SO₂

Question 41

Which of the following liquids has the $\underline{\text{ lowest }}$ enthalpy of vaporization?

A) C₂H₆
B) C₃H₈
C) C₄H₁₀
D) C₅H₁₂
E) C₆H₁₄

Question 42

In a certain mountain range,water boils at 93°C.What is the atmospheric pressure under these conditions? The enthalpy of vaporization of water at 100°C is 40.7 kJ/mol.(R = 8.314 J/K·mol; 1 atm = 760 mmHg)

A) 2040 mmHg
B) 278 mmHg
C) 591 mmHg
D) 977 mmHg
E) 283 mmHg

Question 43

The heat of vaporization of benzene,C₆H₆,is 30.7 kJ/mol at its boiling point of 80.1 ^$\circ$ C.How much energy in the form of heat is required to vaporize 148 g benzene at its boiling point?

A) 0.207 kJ
B) 4.82 kJ
C) 16.2 kJ
D) 58.2 kJ
E) kJ

Question 44

Xenon has an enthalpy of vaporization of 12.6 kJ/mol and a vapor pressure of 1.00 atm at -108.0 ^$\circ$ C.What is the vapor pressure of xenon at -148.0 ^$\circ$ C? (R = 8.314 J/K.mol)

A) 0.053 atm
B) 0.73 atm
C) 0.93 atm
D) 0.99 atm
E) 19 atm

Question 45

Mount Everest rises to a height of 8.850 $\times$ 10³ m above sea level.At this height,the atmospheric pressure is 231 mm Hg.At what temperature (in ^$\circ$ C)does water boil at the summit of Mount Everest? The vapor pressure of water at 373 K is 760.0 mm Hg.( $\Delta$ _vap ^$\circ$ for H₂O = 40.7 kJ/mol and R = 8.314 J/K.mol)

A) 4.07 ^$\circ$ C
B) 69.0 ^$\circ$ C
C) 72 ^$\circ$ C
D) 87 ^$\circ$ C
E) 364 ^$\circ$ C

Question 46

A liquid has an enthalpy of vaporization of 30.4 kJ/mol.At 269 K it has a vapor pressure of 102 mmHg.What is the normal boiling point of this liquid? (R = 8.314 J/(K· mol))

A) 287 K
B) 316 K
C) 269 K
D) 253 K
E) 234 K

Question 47

On a relative basis,the weaker the intermolecular forces in a substance are,

A) the larger is its heat of vaporization.
B) the more it deviates from the ideal gas law.
C) the greater is its vapor pressure at a particular temperature.
D) the larger is its molar heat capacity as a liquid.
E) the higher is its boiling point.

Question 48

A particular compound has an enthalpy of vaporization of 28300 J/mol.At 281 K it has a vapor pressure of 101 mmHg.What is its vapor pressure at 301 K? (R = 8.31 J/K·mol; 1 atm = 760 mmHg)

A) 98.8 mmHg
B) 123 mmHg
C) 45.2 mmHg
D) 226 mmHg
E) 103 mmHg

Question 49

At its boiling point of 58.8 ^$\circ$ C,4.39 kJ of heat is required to vaporize 23.4 g of bromine (Br₂).What is the molar enthalpy of vaporization of bromine?

A) 0.643 kJ/mol
B) 0.188 kJ/mol
C) 30.0 kJ/mol
D) 5.33 kJ/mol
E) 36.39 kJ/mol

Question 50

Ethanol has an enthalpy of vaporization of 42.3 kJ/mol.The compound has a vapor pressure of 1.00 atm at 78.3 ^$\circ$ C.At what temperature is the vapor pressure equal to 0.800 atm? (R = 8.314 J/K.mol)

A) -83.8 ^$\circ$ C
B) -24.4 ^$\circ$ C
C) 62.6 ^$\circ$ C
D) 73.0 ^$\circ$ C
E) 78.0 ^$\circ$ C

Question 51

Sulfur dioxide has a vapor pressure of 462.7 mm Hg at -21.0 ^$\circ$ C and a vapor pressure of 140.5 mm Hg at -44.0 ^$\circ$ C.What is the enthalpy of vaporization of sulfur dioxide? (R = 8.314 J/K.mol)

A) 0.398 kJ/mol
B) 6.33 kJ/mol
C) 14.0 kJ/mol
D) 24.9 kJ/mol
E) 39.8 kJ/mol

Question 52

Freon-113,C₂Cl₃F₃,has an enthalpy of vaporization of 27.0 kJ/mol and a normal boiling point of 48.0 ^$\circ$ C.What is the vapor pressure (in atm)of Freon-113 at 22.0 ^$\circ$ C? (R = 8.314 J/K.mol)

A) 0.21 atm
B) 0.35 atm
C) 0.41 atm
D) 0.46 atm
E) 4.4 atm

Question 53

At 10.0^oC,the vapor pressure of nitric acid is 26.6 mmHg,and at 50.0^oC,the vapor pressure is 208 mmHg.Using this information,calculate the heat of vaporization ( $\Delta$ _vapH)of nitric acid.(R = 8.314 J/K.mol)

A) 25.6 kJ/mol
B) 39.1 kJ/mol
C) 48.4 kJ/mol
D) 225 kJ/mol
E) 566 kJ/mol

Question 54

Equilibrium is established between a liquid and its vapor when

A) the rate of evaporation equals the rate of condensation.
B) equal masses exist in the liquid and gas phases.
C) equal concentrations (in molarity)exist in the liquid and gas phases.
D) all the liquid has evaporated.
E) the liquid ceases to evaporate and the gas ceases to condense.

Question 55

The vapor pressure of a given liquid will increase if

A) the liquid is moved to a container in which its surface area is very much larger.
B) the volume of the liquid is increased.
C) the temperature is increased.
D) the volume of the vapor phase is increased.
E) a more volatile liquid is added to the given liquid.

Question 56

At 75.0 ^$\circ$ C,water has an equilibrium vapor pressure of 289.1 mm Hg.If 4.22 g H₂O is sealed in an evacuated 5.00 L flask and heated to 75.0 ^$\circ$ C,what mass of H₂O will be found in the gas phase when liquid-vapor equilibrium is established? Assume any liquid remaining in the flask has a negligible volume.(R = 0.08206 L.atm/mol.K,1 atm = 760 mm Hg)

A) 0.834 g
B) 1.20 g
C) 1.92 g
D) 3.02 g
E) 4.22 g

Question 57

Ammonia,NH₃,is used as a refrigerant.At its boiling point of -33 ^$\circ$ C,the standard enthalpy of vaporization of ammonia is 23.3 kJ/mol.How much heat is released when 50.0 g of ammonia is condensed at -33 ^$\circ$ C?

A) -0.466 kJ
B) -7.94 kJ
C) -36.6 kJ
D) -68.4 kJ
E) -1.17 $\times$ 10³ kJ

Question 58

For a particular liquid,raising its temperature from 321 K to 352 K causes its vapor pressure to double.What is the enthalpy of vaporization of this liquid? (R = 8.314 J/K · mol)

A) 21.0 kJ/mol
B) 186 kJ/mol
C) 3.29 kJ/mol
D) 383 kJ/mol
E) 179 kJ/mol

Question 59

If 3.21 g of water is sealed in an evacuated 2.52 L flask and heated to the normal boiling point of 373 K,what is the pressure in the flask? (R = 0.08206 L.atm/mol.K)

A) 0.231 atm
B) 0.462 atm
C) 1.00 atm
D) 2.16 atm
E) 39.0 atm

Question 60

A linear relationship exists between the natural logarithm of the vapor pressure of a gas and the reciprocal of its temperature (in kelvin).What is the slope of the line?

A)
B)
C) T
D)
E)

Question 61

A cup of oil takes longer to pour from a glass than a cup of water.A liquid's resistance to flow is referred to as its ________.

Question 62

Capillary action is ____

A) resistance to flow.
B) the rate of collisions for gas molecules.
C) the energy required to overcome the attractive forces between molecules in the liquid state to form a gas.
D) the force required to expand the surface of a liquid.
E) the drawing of a liquid up the inside of a small-bore tube when adhesive forces exceed cohesive forces.

Question 63

The ________ equation relates the equilibrium vapor pressure of a volatile liquid to the molar enthalpy of vaporization at a given temperature.

Question 64

________ is a measure of the degree to which the electron cloud surrounding an atom or molecule can be distorted in an electric field.

Question 65

When a glass tube with a small diameter is placed in water,the water rises in the tube.This is known as ________ action.

Question 66

Above its critical temperature and pressure,a substance becomes a(n)________ fluid.

Question 67

Make a sketch to show the hydrogen bonding between two acetic acid molecules (HC₂H₃O₂).

Question 68

Which ion,K⁺ or Ca²⁺,is expected to have the more negative enthalpy of hydration? Why?

Question 69

Which of the following phase transitions is/are endothermic?
1)liquid water freezing to a solid at its normal freezing point of 0.0 ^$\circ$ C.
2)the sublimation of solid carbon dioxide into the gas phase.
3)gaseous sulfur dioxide condensing into a liquid at its boiling point of -10.0 ^$\circ$ C.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 70

Volatile liquids are described by all of the following $\textbf{ except:}$

A) Volatile liquids are easily vaporized.
B) Volatile liquids have relatively high vapor pressures.
C) Volatile liquids have strong cohesive forces.
D) Volatile liquids have weak intermolecular forces.
E) All of these describe volatile liquids.

Question 71

Normal boiling point is defined as

A) the temperature at which the vapor pressure of a liquid equals 1 atm.
B) the pressure at which any liquid boils at 373.15 K.
C) the temperature at which water boils in a vacuum.
D) the temperature at which the liquid and gaseous phases of a substance have equal densities.
E) the temperature at which the enthalpy of vaporization equals 100.0 kJ/mol.

Question 72

Two important allotropes of phosphorus are white phosphorus and red phosphorus.White phosphorus,P₄,has a melting point of 44.1 ^$\circ$ C and spontaneously reacts with oxygen.Red phosphorus,a network solid,melts at 280 ^$\circ$ C and is stable in air.Use your knowledge of intermolecular and intramolecular bonding to explain why these two forms of the same element have such different properties.

Question 73

The toughness of the skin of a liquid is a measure of its ____.

A) meniscus curvature
B) adhesive forces
C) cohesive forces
D) viscosity
E) surface tension

Question 74

What is responsible for capillary action,a property of liquids?

A) cohesive forces
B) adhesive forces
C) viscosity
D) A and B
E) A,B,and C

Question 75

Which of the following properties of water can be attributed to hydrogen bonding?
1)high melting point
2)high heat of vaporization
3)low vapor pressure
4)high surface tension

A) 1 and 3
B) 2 and 3
C) 2,3,and 4
D) 1,3,and 4
E) 1,2,3,and 4

Question 76

Which of the following statements is/are CORRECT?
1)If the intermolecular forces in a liquid decrease,the normal boiling point of the liquid decreases.
2)If the temperature of a liquid increases,the equilibrium vapor pressure increases.
3)If the surface area of a liquid increases,the equilibrium vapor pressure of the liquid increases.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 77

Which of the following are valid reasons why vegetable oil has a greater viscosity than diethyl ether,CH₃OCH₃?
1)Oil molecules have long chains that become entangled.
2)Unlike diethyl ether,oil molecules are not held together by hydrogen bonds.
3)Intermolecular forces are greater for the larger oil molecules.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 2 and 3

Question 78

The best explanation for the existence of a meniscus observed when water is placed in a glass tube of small diameter is

A) the surface tension of the water causes it to "bead up" inside the container.
B) the attractive forces between the water molecules and the walls of the container are greater than the attractive forces between the water molecules.
C) the molecules are forced closer together because of London forces.
D) the viscosity of the water is greater than the viscosity of the glass.
E) the hydrogen bonds between water molecules are greater than the attractions between the water molecules and the walls of the container.

Question 79

Which of the following statements concerning a supercritical fluid (SCF)is/are CORRECT?
1)An SCF has a density similar to that of a gas.
2)An SCF has a viscosity similar to that of a liquid.
3)An SCF fills its entire container,much like a gas.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 1,2,and 3