Deck 10: Liquids,solids,and Phase Changes

Question 1

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

Answer 1

hydrogen bonding

Question 2

Which compound below could have a zero dipole moment?

A)CCl₂F₂ (tetrahedral)
B)CuCl₂F₂ (tetrahedral)
C)PtCl₂F₂ (square planar)
D)SCl₂F₂ (see-saw)

Answer 2

PtCl₂F₂ (square planar)

Question 3

The bonds in the polyatomic ion CO₃^2- are classified as

A)ionic
B)metallic
C)nonpolar covalent
D)polar covalent

Answer 3

polar covalent

Question 4

The HI bond has a length of 161 pm and 4.92% ionic character.What is the experimental dipole moment of HI?

A)0)380 D
B)0)772 D
C)3)80 D
D)7)72 D

Question 5

AgCl is found to have 78.1% ionic character,and its gas phase dipole moment is 11.5 D.What is the distance between the Ag and Cl atoms in gaseous AgCl?

A)9)19 x 10^-10 pm
B)14.7 pm
C)307 pm
D)903 pm

Question 6

Which is expected to have the largest dispersion forces?

A)C₂H₆
B)C₈H₁₈
C)N₂
D)CO₂

Question 7

Which of the following exhibits ion-dipole forces?

A)NaCl(s)
B)NaCl(aq)
C)Na(s)
D)Cl₂(g)

Question 8

The dipole moment of ClF is 0.88 D,and its bond length is 163 pm.What is the percent ionic character of the Cl-F bond?

A)0)54%
B)7)8%
C)11%
D)25%

Question 9

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 10

Which covalent bond is the most polar?

A)N-F
B)C-F
C)Cl-F
D)F-F

Question 11

Which has a dipole moment?

A)CO₂
B)CO₃^2-
C)SO₂
D)SO₄^2-

Question 12

Which of the following compounds exhibits hydrogen bonding?

A)CH₃Cl
B)HI
C)H₃C-O-CH₃
D)NH₃

Question 13

The dipole moment of BrF is 1.29 D,and its bond length is 178 pm.What is the percent ionic character of the Br-F bond?

A)3)9%
B)8)5%
C)15%
D)33%

Question 14

Which substance in each of the following pairs is expected to have the larger dispersion forces?

A)Br₂ in set I and n-butane in set II
B)Br₂ in set I and isobutane in set II
C)I₂ in set I and n-butane in set II
D)I₂ in set I and isobutane in set II

Question 15

In liquid methanol,CH₃OH,which intermolecular forces are present?

A)Dispersion,hydrogen bonding and dipole-dipole forces are present.
B)Only dipole-dipole and ion-dipole forces are present.
C)Only dispersion and dipole-dipole forces are present.
D)Only hydrogen bonding forces are present.

Question 16

Which compound,shown with its dipole moment,is expected to exhibit the smallest percent ionic character?

A)HCl,1.11 D
B)HF,1.83 D
C)LiH,6.00 D
D)LiF,6.28 D

Question 17

Which has the smallest dipole-dipole forces?

A)CH₃F
B)HCl
C)N₂
D)CO

Question 18

Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions?

A)N₂
B)HBr
C)CO₂
D)H₂O

Question 19

Which of the following should have the largest dipole moment?

A)H₂(g)
B)CO₂(g)
C)KCl(g)
D)CH₃F(g)

Question 20

Which of the following molecules does not have a dipole moment?

A)CH₂=CH₂
B)NH₃
C)CH₃NH₂
D)HCl

Question 21

Which of the following compounds has the highest boiling point?

A)H₂O
B)HCl
C)H₂S
D)NH₃

Question 22

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 23

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 24

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 25

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 26

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

Question 27

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 10.0 g of ethyl chloride?

A)4)09 kJ
B)170 kJ
C)264 kJ
D)1700 kJ

Question 28

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 29

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 30

Which of the following substances has the highest boiling point?

A)CH₃-CH₂-CH₂-CH₂-CH₃
B)Xe
C)CH₃-CH₂-CH₃
D)(CH₃)₄C

Question 31

When a liquid is heated at its boiling point,the

A)covalent bonds are broken,allowing vaporization to occur.
B)temperature of the liquid increases.
C)temperature of the liquid remains the same as long as any liquid is present.
D)temperature of the vapor phase increases.

Question 32

Which of the following phase changes has a positive value for its entropy change?

A)boiling water
B)formation of raindrops from a cloud
C)making dry ice from gaseous CO₂
D)making ice cubes from liquid water

Question 33

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 34

How much heat is released when 75.0 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)54.8 kJ
B)195 kJ
C)228 kJ
D)248 kJ

Question 35

The property of a liquid that measure the liquid's resistance to flow is

A)boiling point.
B)heat of vaporization.
C)surface tension.
D)viscosity.

Question 36

Which is expected to have the highest surface tension at 25°?

A)C₅H₁₂
B)C₆H₆
C)C₂H₅OH
D)C₃H₅(OH)₃

Question 37

Which of the following is most likely to have the highest viscosity at 25°C?

A)C₄H₁₀
B)HOCH₂CH₂OH
C)C₈H₁₈
D)C₂H₅NH₂

Question 38

For which of the following phase changes is the sign of ΔS negative?

A)boiling of water
B)formation of snow from water vapor in clouds
C)melting of ice cream
D)sublimation of I₂

Question 39

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 40

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 41

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

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

Question 42

Which is classified as an amorphous solid?

A)palladium(II)chloride
B)phosphorus tetrachloride
C)plastic
D)platinum

Question 43

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 44

Which type of bonding does Mg form upon solidification?

A)covalent network
B)ionic
C)metallic
D)molecular

Question 45

Which of the following forms a molecular solid?

A)CaO
B)C₁₀H₂₂
C)C(graphite)
D)gold

Question 46

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 47

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

Question 48

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 49

Which of the following forms an ionic solid?

A)Ag
B)C₇H₁₅NH₂
C)RbI
D)SO₃

Question 50

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 51

A kitchen pressure cooker operates at 1.50 atm.The ΔH_vap of water is 40.7 kJ/mol.What is the boiling point of water in the pressure cooker?

A)362 K
B)373 K
C)385 K
D)410 K

Question 52

Which of the following compounds forms a covalent network solid?

A)C₈H₁₈
B)NO₂
C)SiO₂
D)SnCl₄

Question 53

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 54

Solids having no ordered long-range structure are classified as

A)amorphous
B)crystalline
C)metallic
D)molecular

Question 55

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 56

Arrange the following in order of increasing boiling point.
CH₃CH₂OH CH₃CH₂CH₃ H₃C-O-CH₃ CH₃CH₂NH₂
I II III IV

A)IV < III < II < I
B)II < III < IV < I
C)I < IV < III < II
D)II < III < I < IV

Question 57

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 58

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

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

Question 59

Which of the following compounds has the highest boiling point?

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

Question 60

Which of the following compounds forms a covalent network solid?

A)Li
B)C (diamond)
C)O₂
D)CO₂

Question 61

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

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

Question 62

Cesium has a radius of 272 pm and crystallizes in a face-centered cubic unit cell.What is the edge length of the unit cell?

A)314 pm
B)385 pm
C)544 pm
D)769 pm

Question 63

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 64

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 65

Which of the following is not an allotrope of carbon?

A)coal
B)diamond
C)fullerene
D)graphite

Question 66

O₂ and O₃ are ________ of oxygen.

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

Question 67

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 68

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 69

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

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

Question 70

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

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

Question 71

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 72

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 73

What is the edge length of a face-centered cubic unit cell made up of atoms having a radius of 175 pm?

A)247 pm
B)495 pm
C)700 pm
D)1400 pm

Question 74

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 75

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 76

Silver crystallizes in a face-centered cubic structure.What is the edge length of the unit cell if the atomic radius of silver is 144 pm?

A)204 pm
B)288 pm
C)333 pm
D)407 pm

Question 77

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

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

Question 78

Rhodium has a face-centered cubic structure and has a density of 12.4 g/cm³.What is its atomic radius?

A)134 pm
B)268 pm
C)380 pm
D)1070 pm

Question 79

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 80

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.