Deck 11: Liquids, solids, and Phase Changes

Question 1

For the process: HNO₃(g)⇌ HNO₃(l),ΔH° is -39.04 kJ/mol and ΔS° is -111.74 J/(mol ∙ K).What is the normal boiling point of pure HNO₃?

A)2.86°C
B)76.2°C
C)270.3°C
D)349.4°C

Answer 1

76.2°C

Question 2

Which of the following best explains why ΔH_vap is usually higher than ΔH_fusion?

A)Vaporization occurs at high temperature.
B)Vaporization involves the breaking of bonds within molecules.
C)Vaporization involves the breaking of all bonds between molecules.
D)Vaporization increases the entropy of molecules.

Answer 2

Vaporization involves the breaking of all bonds between molecules.

Question 3

While mercury is very useful in barometers,mercury vapor is toxic.Given that mercury has a ΔH_vap of 59.11 kJ/mol and its normal boiling point is 356.7°C,calculate the vapor pressure in mm Hg at room temperature,25°C.

A)2.68 × 10^-3 mm Hg
B)2.99 mm Hg
C)372 mm Hg
D)753 mm Hg

Answer 3

2.68 × 10^-3 mm Hg

Question 4

When a narrow diameter glass tube is inserted into a body of water,water rises in the tube and its surface inside is concave upwards.Which statement,concerning the strength of the intermolecular forces between glass and water molecules compared to those between water molecules,is accurate?

A)The forces of attraction between the glass and water are weaker than those in water.
B)The forces of attraction between the glass and water are stronger than those in water.
C)The forces of attraction between the glass and water are the same as those in water.
D)Intermolecular forces are irrelevant to this situation.

Question 5

The vapor pressure of a pure liquid increases as the

A)average kinetic energy of the molecules in the liquid phase decreases.
B)intermolecular attractive forces increase.
C)temperature of the liquid phase decreases.
D)temperature of the liquid phase increases.

Question 6

Ethyl chloride,C₂H₅Cl,is used as a local anesthetic.It works by cooling tissue as it vaporizes.The heat of vaporization is 26.4 kJ/mol.How much heat could be removed by 60.0 g of ethyl chloride?

A)24.6 kJ
B)1584 kJ
C)2.28 kJ
D)1703 kJ

Question 7

How much heat is released when 125.0 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)91.3 kJ
B)325 kJ
C)380 kJ
D)413 kJ

Question 8

As a liquid evaporates at a temperature below its boiling point,the temperature of the liquid

A)decreases.
B)decreases at low temperatures,but increases at high temperatures.
C)increases.
D)remains unchanged.

Question 9

Molecules of a liquid can pass into the vapor phase only if the

A)liquid has little surface tension.
B)molecules have sufficient kinetic energy to overcome the intermolecular forces in the liquid.
C)temperature of the liquid is near its boiling point.
D)vapor pressure of the liquid is high.

Question 10

Which of the following is expected to have the greatest viscosity?

A)C₅H₁₂
B)C₆H₁₄
C)C₅H₁₁OH
D)CH₄

Question 11

The magnitude of the heats of vaporization,fusion and sublimation of a substance reflect the

A)density of the substance.
B)magnitudes of the boiling and melting points of the substance.
C)strength of the covalent bonds between atoms in each molecule of the substance.
D)strength of the intermolecular forces of the substance.

Question 12

Which of the following compounds has the highest boiling point?

A)CH₃CH₂OH
B)HOCH₂CH₂OH
C)H₃C-O-CH₃
D)CH₃CH₂CH₂CH₃

Question 13

CFC-11 (trichlorofluoromethane,CCl₃F)has been used for many years as the working fluid in refrigerators.Given its heat of vaporization is 26.88 kJ/mol and its entropy of vaporization is 90.51 J/(mol ∙ K),what is the boiling point of CFC-11?

A)-272.9°C
B)0.297°C
C)2.44°C
D)23.8°C

Question 14

Bromine is one of only two elements that is a liquid at room temperature.Bromine has a heat of vaporization of 30.91 kJ/mol and its boiling point is 59°C.What is the entropy of vaporization for bromine?

A)-301 J/(mol ∙ K)
B)-93.1 J/(mol ∙ K)
C)10.7 J/(mol ∙ K)
D)93.1 J/(mol ∙ K)

Question 15

The normal boiling point for HBr is higher than the normal boiling point for HCl.This can be explained by

A)larger dipole-dipole forces for HBr.
B)larger dispersion forces for HBr.
C)larger hydrogen-bond forces for HBr.
D)larger dipole-dipole forces,larger dispersion forces,and larger hydrogen-bond forces for HBr.

Question 16

For a particular compound,which is expected to be the largest in general?

A)the heat required to raise the temperature of one mole of the gas 10.0°C
B)the heat required to raise the temperature of one mole of the liquid 10.0°C
C)the molar heat of fusion at the normal melting point
D)the molar heat of vaporization at the normal boiling point

Question 17

Hydroquinone is an antioxidant that is also used as a photographic reducer and developer.The normal boiling point of hydroquinone is 310°C.Calculate the pressure at which hydroquinone will boil at 200°C given that its ΔH_vap is 73.38 kJ/mol.

A)1.210 × 10^-4 mm Hg
B)1.35 mm Hg
C)22.5 mm Hg
D)757 mm Hg

Question 18

When a substance melts at its normal melting point,the sign of ΔH is ________ and the sign of ΔS of this phase change is ________.

A)+,-
B)-,+
C)+,+
D)-,-

Question 19

The normal boiling point occurs when the

A)intermolecular forces within the liquid phase are broken.
B)temperature of the pure liquid equals the external temperature.
C)vapor pressure of a pure liquid equals an external pressure of one atmosphere.
D)vapor pressure of the liquid equals the external pressure.

Question 20

Which of the intermolecular forces is the most important contributor to the high surface tension shown by water?

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

Question 21

Iron crystallizes in a body-centered cubic cell having an edge length of 287 pm.What is the density of iron in g/cm³?

A)1.99
B)7.85
C)11.9
D)15.9

Question 22

Which of the following liquids will exhibit the highest vapor pressure?

A)Br₂,bp = 58.8°C
B)CH₃OH,bp = 64.7°C
C)H₂O,bp = 100°C
D)All exhibit the same vapor pressure.

Question 23

How many unit cells share an atom that is on the face of a face-centered cubic unit cell?

A)1
B)2
C)4
D)8

Question 24

How many atoms are in one body-centered cubic unit cell of a metal?

A)1
B)2
C)3
D)4

Question 25

Palladium has a face-centered cubic structure and has a density of 12.023 g/cm³.What is its atomic radius?

A)388 pm
B)151 pm
C)220 pm
D)245 pm

Question 26

The vapor pressure of liquid chloroform,CHCl₃,is 400.0 torr at 24.1°C and 100.0 torr at -6.3°C.What is ΔH_vap of chloroform?

A)15.3 kJ/mol
B)30.1 kJ/mol
C)57.6 kJ/mol
D)86.7 kJ/mol

Question 27

Which of the following statements is not consistent with the properties of a molecular solid?

A)a compound that conducts electricity when molten
B)a low melting solid
C)a solid formed by the combination of two nonmetallic elements
D)a solid that is a nonconductor of electricity

Question 28

Cubic closest-packing

A)has a body-centered cubic unit cell.
B)has a face-centered cubic unit cell.
C)has a simple cubic unit cell.
D)has the same unit cell as hexagonal closest-packing.

Question 29

Which type of spherical packing has the most unused space?

A)body-centered cubic
B)cubic closest-packed
C)cubic closest-packed and hexagonal closest-packed
D)simple cubic

Question 30

When cubic unit cells stack together,how many unit cells share a common corner?

A)2
B)4
C)6
D)8

Question 31

The structure of a solid can be determined by diffraction of radiation in which region of the electromagnetic radiation spectrum?

A)infrared
B)microwave
C)visible
D)X-ray

Question 32

An element forms a body-centered cubic crystalline substance.The edge length of the unit cell is 287 pm and the density of the crystal is 7.92 g/cm³.Calculate the atomic weight of the substance.

A)45.0 amu
B)48.0 amu
C)56.4 amu
D)63.5 amu

Question 33

The wavelength of light used to observe an object must be ________ than the object itself.

A)larger
B)smaller
C)of higher energy
D)of lower energy

Question 34

Iridium crystallizes in a face-centered cubic structure.What is the edge length of the unit cell if the atomic radius of silver is 180 pm?

A)441 pm
B)64 pm
C)38 pm
D)509 pm

Question 35

A crystalline solid of unknown origin forms an aqueous solution that conducts an electrical current.The solid has a high melting point and shatters when struck with a hammer.The solid is likely to be

A)a covalent network solid.
B)an ionic solid.
C)a metallic solid.
D)a molecular solid.

Question 36

What is the edge length of a face-centered cubic unit cell made up of atoms having a radius of 200 pm?

A)71 pm
B)566 pm
C)20 pm
D)110 pm

Question 37

Chromium crystallizes in a body-centered cubic structure.What is the coordination number of each atom?

A)4
B)6
C)8
D)12

Question 38

The highest coordination number for spherical packing is found in the

A)body-centered cubic structure.
B)simple cubic structure.
C)body-centered cubic and face-centered cubic.
D)cubic closest-packing and hexagonal closest packing.

Question 39

How many atoms are in one face-centered cubic unit cell of a metal?

A)1
B)2
C)3
D)4

Question 40

Lead has a radius of 154 pm and crystallizes in a face-centered cubic unit cell.What is the edge length of the unit cell?

A)35 pm
B)54 pm
C)1232 pm
D)436 pm

Question 41

How many Br^- ions are around each K⁺ ion in KBr,which has a cubic unit cell with Br^- ions on each corner and each face?

A)1
B)4
C)6
D)8

Question 42

.
If figure (1)represents the vapor pressure of water at 25°C in a 1 liter container,which figure represents the vapor pressure of water at 25°C in a 2 liter container?

A)figure (2)
B)figure (3)
C)figure (4)

Question 43

The plots below represent vapor pressure vs.temperature curves for diethyl ether,ethanol,mercury,and water,not necessarily in that order.
Based on the relative strengths of the intermolecular forces of attraction of each substance,which is the most likely vapor pressure vs.temperature curve for water?

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

Question 44

An ionic compound crystallizes in a unit cell having a face-centered cubic array of anions,X^-,and half of the tetrahedral holes filled with metal ions,Mⁿ⁺ The empirical formula of this ionic compound is

A)MX.
B)MX₂.
C)M₂X.
D)M₂X₇.

Question 45

A binary ionic compound,M_xA_y,crystallizes in a cubic structure that contains eight anions (A)entirely within its unit cell and a cation (M)on each corner and on each face.What is the empirical formula of this compound?

A)MA
B)MA₂
C)M₂A
D)M₄A₈

Question 46

O₂ and O₃ are ________ of oxygen.

A)allotropes
B)isomers
C)isotopes
D)stereomers

Question 47

The edge length of a face-centered cubic lattice of NaCl is 564 pm.What is the density of NaCl in g/cm³?

A)0.720
B)1.08
C)2.16
D)4.32

Question 48

An ionic compound crystallizes in a unit cell having a face-centered cubic array of metal ions,Mⁿ⁺,and all of the tetrahedral holes occupied by anions,X^-.The empirical formula of this ionic compound is

A)MX.
B)MX₂.
C)M₂X.
D)M₇X₄.

Question 49

The plots below represent vapor pressure vs.temperature curves for diethyl ether,ethanol,mercury,and water,not necessarily in that order.
Based on the relative strengths of the intermolecular forces of attraction of each substance,which is the most likely vapor pressure vs.temperature curve for mercury?

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

Question 50

A supercritical fluid refers to a substance

A)above both its critical temperature and its critical pressure.
B)at its triple point.
C)that is in the liquid crystal state.
D)with a viscosity of zero.

Question 51

The plots below represent vapor pressure vs.temperature curves for diethyl ether,ethanol,mercury,and water,not necessarily in that order.
Based on the relative strengths of the intermolecular forces of attraction of each substance,which is the most likely vapor pressure vs.temperature curve for ethanol?

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

Question 52

If figure (1)represents the vapor pressure of diethyl ether,CH₃CH₂OCH₂CH₃,at 25°C,which figure represents the vapor pressure of ethanol at 25°C?

A)figure (2)
B)figure (3)
C)figure (4)

Question 53

A safe method of removing caffeine from coffee is through the use of

A)supercritical carbon dioxide.
B)benzene.
C)methylene chloride.
D)water.

Question 54

The critical temperature of a substance is the

A)highest temperature at which the liquid phase can exist in equilibrium with the gas phase.
B)temperature above which the compound decomposes.
C)temperature at which all three phases can exist in equilibrium.
D)temperature at which sublimation occurs.

Question 55

KBr crystallizes in a cubic unit cell with Br^- ions on each corner and each face.How many K⁺ ions and Br^- ions are in each unit cell of KBr?

A)1 K⁺ ion and 1 Br^- ion
B)2 K⁺ ions and 2 Br^- ions
C)4 K⁺ ions and 4 Br^- ions
D)8 K⁺ ions and 8 Br^- ions

Question 56

If figure (1)represents the vapor pressure of water,at 25°C,which figure represents the vapor pressure of mercury at 25°C?

A)figure (2)
B)figure (3)
C)figure (4)

Question 57

Which transition could occur if a solid is heated at a pressure below the triple point pressure?

A)condensation
B)deposition
C)melting
D)sublimation

Question 58

If figure (1)represents the vapor pressure of water at 25°C,which figure represents the vapor pressure of ethanol,CH₃CH₂OH at 25°C?

A)figure (2)
B)figure (3)
C)figure (4)

Question 59

.
If figure (1)represents the vapor pressure of water at 25°C,which figure represents the vapor pressure of water at 45°C?

A)figure (2)
B)figure (3)
C)figure (4)

Question 60

The plots below represent vapor pressure vs.temperature curves for diethyl ether,ethanol,mercury,and water,not necessarily in that order.
Based on the relative strengths of the intermolecular forces of attraction of each substance,which is the most likely vapor pressure vs.temperature curve for diethyl ether?

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

Question 61

A certain mineral,M_xM'_yA_z,crystallizes in the cubic unit cell shown below.M and M' represent cations and A represents the anions.
How many anions are in the unit cell?

A)1
B)2
C)3
D)6

Question 62

The temperature and pressure at which all three phases can coexist in equilibrium is

A)0.25 atm and 110°C.
B)1.0 atm and 140°C.
C)1.25 atm and 300°C.
D)0.45 atm and 130°C.

Question 63

Use the diagram below to answer the following questions.
According to the diagram,the solid phase of this substance

A)has the same density as the liquid phase.
B)is less dense than water.
C)is less dense than the liquid phase.
D)is more dense than the liquid phase.

Question 64

A certain mineral crystallizes in the cubic unit cell shown below.M represents the cations and A represents the anions.What is the empirical formula of the mineral?

A)MA
B)MA₂
C)M₂A
D)M₄A₄

Question 65

From the phase diagram above,the minimum pressure at which this substance can exist in the liquid phase is

A)0.25 atm.
B)0.45 atm.
C)1.0 atm.
D)1.2 atm.

Question 66

A certain mineral,M_xM'_yA_z,crystallizes in the cubic unit cell shown below.M and M' represent cations and A represents the anions.
What is the empirical formula of the mineral?

A)MM'A
B)MM'A₃
C)M₂M'A₃
D)M₈M'A₆

Question 67

A certain mineral,M_xM'_yA_z,crystallizes in the cubic unit cell shown below.M and M' represent cations and A represents the anions.
How many cations M are in the unit cell?

A)1
B)2
C)4
D)8

Question 68

Use the diagram below to answer the following questions.
Melting occurs along the

A)AC line.
B)CB line.
C)CD line.
D)All of these

Question 69

Use the diagram below to answer the following questions.
The solid and liquid phases can exist in equilibrium along line

A)AC.
B)CB.
C)CD.
D)BD.

Question 70

From the plot of vapor pressure as a function of temperature shown below,the normal boiling point for tert-butyl alcohol is approximately

A)0°C.
B)40°C.
C)85°C.
D)100°C.

Question 71

Identify the packing in the figure shown below.

A)body-centered cubic
B)cubic closest packed (face-centered cubic)
C)hexagonal closest packed
D)simple cubic

Question 72

Identify the packing in the figure shown below.

A)body-centered cubic
B)cubic closest packed (face-centered cubic)
C)hexagonal closest packed
D)simple cubic

Question 73

A certain mineral,M_xM'_yA_z,crystallizes in the cubic unit cell shown below.M and M' represent cations and A represents the anions.
If cation M has a 2+ charge and anion A has a 2- charge,what is the oxidation state of cation M'?

A)+1
B)+2
C)+3
D)+4

Question 74

The picture shown below represents a two-dimensional lattice of atoms M and X.
Which of the areas designated A,B,and C are smallest repeating units,analogous to two-dimensional unit cells?

A)only A
B)only B
C)only C
D)A,B,or C

Question 75

Identify the packing in the figure shown below.

A)body-centered cubic
B)cubic closest packed (face-centered cubic)
C)hexagonal closest packed
D)simple cubic

Question 76

Consider a compound that undergoes sublimation at 125°C and a pressure of one atm.Which of the following could be a heating curve appropriate for heating the compound from 100°C to 150°C?

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

Question 77

A certain mineral crystallizes in the cubic unit cell shown below.
What kind of packing do the anions adopt?

A)body-centered cubic
B)cubic closest packed (face-centered cubic)
C)hexagonal closest packed
D)simple cubic

Question 78

A certain mineral crystallizes in the cubic unit cell shown below.
How many cations and how many anions are in the unit cell?

A)4 cations and 4 anions
B)4 cations and 8 anions
C)4 cations and 14 anions
D)8 cations and 4 anions

Question 79

Identify the packing in the figure shown below.

A)body-centered cubic
B)cubic closest packed (face-centered cubic)
C)hexagonal closest packed
D)simple cubic

Question 80

The picture shown below represents a two-dimensional lattice of atoms M and X.
What is the formula of the compound formed from M and X?

A)MX
B)MX₂
C)MX₃
D)MX₄