Question 1

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

Accepted Answer

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

Question 2

For each of the following pairs of compounds, identify the one that is more likely to be soluble in water. Explain the rationale for your choice.
(A) CCl4 or CHCl3
(B) CH3OH or C5H11OH
(C) NaF or MgO

Accepted Answer

(A) CHCl₃, because it has a dipole moment to interact more strongly with water. CCl₄does not have a dipole moment.
(B) CH₃OH, because it has a dipole moment, can hydrogen-bond with water, and has a small hydrocarbon part. C₅H₁₁OH has a large hydrocarbon part, so it disrupts the hydrogen bonding in water, which is unfavorable.
(C) NaF, because the ions only have single charges so the

\mathrm { Na } ^ { + } \mathrm { F } ^ { - }

attractions are more easily overcome than in MgO, where ionic charges are 2+ and 2-.

Question 3

Boiling points increase in the order HCl < HBr < HI because ________ contribute to the intermolecular interactions.

Accepted Answer

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

Question 4

At the triple point of a substance, ________

Accepted Answer

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. 
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 5

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

Accepted Answer

A)  CO2 
B)  CCl4 
C)  O2 
D)  SiO2 
E)  NH3 
A)  CO2 
B)  CCl4 
C)  O2 
D)  SiO2 
E)  NH3

Question 6

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

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

Which is the dominant interaction between carbon dioxide molecules?

Accepted Answer

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

Question 9

Hydrophilic substances ________

Accepted Answer

A)  are immiscible in water. 
B)  are insoluble in water. 
C)  are soluble in water. 
D)  are hydrated. 
E)  generally do not hydrogen bond. 
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 10

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

Accepted Answer

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. 
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 11

Polarizability refers to ________

Accepted Answer

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. 
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 12

Explain why the boiling point of nitrogen (N2, 77 K) is much lower than that of carbon monoxide (CO, 84 K), even though both have the same number of electrons and protons and nearly the same mass.

Accepted Answer

CO is polar, and the

Question 13

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

Accepted Answer

A)  NaF 
B)  KCl 
C)  RbCl 
D)  BeF2 
E)  NaCl 
A)  NaF 
B)  KCl 
C)  RbCl 
D)  BeF2 
E)  NaCl

Question 14

Which is the dominant interaction that explains the high melting point of table salt, NaCl?

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

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

Accepted Answer

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

Question 17

Which hydride do you predict has the lowest boiling point?

Accepted Answer

A)  CH4 
B)  NH3 
C)  HF 
D)  H2O 
E)  HI 
A)  CH4 
B)  NH3 
C)  HF 
D)  H2O 
E)  HI

Question 18

Melting occurs in going from region ________

Accepted Answer

A)  I to II. 
B)  I to III. 
C)  II to III. 
D)  III to II. 
E)  III to I. 
A)  I to II. 
B)  I to III. 
C)  II to III. 
D)  III to II. 
E)  III to I.

Question 19

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°C. The enthalpy of vaporization of n-pentane is 27.6 kJ/mol, and its boiling point is 36.0°C.

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 10: Intermolecular Forces: The Uniqueness of Water

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

For each of the following pairs of compounds, identify the one that is more likely to be soluble in water. Explain the rationale for your choice. (A) CCl4 or CHCl3 (B) CH3OH or C5H11OH (C) NaF or MgO

Boiling points increase in the order HCl < HBr < HI because ________ contribute to the intermolecular interactions.

At the triple point of a substance, ________

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

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

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

Which is the dominant interaction between carbon dioxide molecules?

Hydrophilic substances ________

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

Polarizability refers to ________

Explain why the boiling point of nitrogen (N2, 77 K) is much lower than that of carbon monoxide (CO, 84 K), even though both have the same number of electrons and protons and nearly the same mass.

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

Which is the dominant interaction that explains the high melting point of table salt, NaCl?

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

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

Which hydride do you predict has the lowest boiling point?

Melting occurs in going from region ________

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

Matter and Energy: The Origin of the Universe

Atoms, Ions, and Molecules: Matter Starts Here

Stoichiometry: Mass, Formulas, and Reactions

Solution Chemistry: The Hydrosphere

Thermochemistry: Energy Changes in Reactions

Properties of Gases: the Air We Breathe

A Quantum Model of Atoms: Waves and Particles

Chemical Bonds: What Makes a Gas a Greenhouse Gas

Molecular Geometry: Shape Determines Function

Solutions: Properties and Behavior

Solids: Structures and Applications

Organic Chemistry: Fuels, Pharmaceuticals, Materials, and Life

Chemical Kinetics: Reactions in the Air We Breathe

Chemical Equilibrium: How Much Product Does a Reaction Really Make

Acid-Base and Solubility Equilibria: Reactions in Soil and Water

Metal Ions: Colorful and Essential

Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

Electrochemistry: the Quest for Clean Energy

Biochemistry: the Compounds of Life

Nuclear Chemistry: Applications to Energy and Medicine

Life and the Periodic Table

Filters

For each of the following pairs of compounds, identify the one that is more likely to be soluble in water. Explain the rationale for your choice. (A) CCl₄ or CHCl₃ (B) CH₃OH or C₅H₁₁OH (C) NaF or MgO

Explain why the boiling point of nitrogen (N₂, 77 K) is much lower than that of carbon monoxide (CO, 84 K), even though both have the same number of electrons and protons and nearly the same mass.