Question 1

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.)

Accepted Answer

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

Question 2

Which hydride do you predict has the highest boiling point?

Accepted Answer

A)  CH4 
B)  SiH4 
C)  GeH4 
D)  SnH4 
E)  PbH4 
A)  CH4 
B)  SiH4 
C)  GeH4 
D)  SnH4 
E)  PbH4

Question 3

CH2F2 has a dipole moment of 1.93 D and a boiling point of -52°C. CH2Cl2 has a dipole moment of 1.60 D and a boiling point of 40°C. Why is the boiling point of dichloromethane so much higher than that of difluoromethane?

Accepted Answer

Both molecules have dipole-dipole and di

Question 4

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

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 5

Which is the dominant interaction between acetone molecules, (CH3)2CO?

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 6

On the phase diagram below, identify the normal melting point.

Accepted Answer

A)  VI 
B)  V 
C)  VII 
D)  IV 
E)  III 
A)  VI 
B)  V 
C)  VII 
D)  IV 
E)  III

Question 7

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

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 8

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

Accepted Answer

A)  NaCl 2 3 
B)  MgCl2 3 
C)  AlCl3 2 3 2 
E)  NaCl 3 2 
A)  NaCl 2 3 
B)  MgCl2 3 
C)  AlCl3 2 3 2 
E)  NaCl 3 2

Question 9

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?

Accepted Answer

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

Question 10

Which is the dominant interaction that leads to the formation of a hydration sphere in a salt solution?

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 11

Would water rise to the same height in a capillary tube made of polyethylene plastic as it does in a glass capillary tube of the same diameter? Polyethylene is a hydrocarbon, and glass is mostly silicon dioxide. Explain.

Accepted Answer

Water will not interact as strongly with

Question 12

Indicate which of the following pairs of compounds is most likely to be miscible.

Accepted Answer

A)  H2O and CH3CH2CH2CH3 
B)  Br2 and HI 
C)  HF and CCl4 
D)  CCl4 and Br2 
E)  CCl4 and NH3 
A)  H2O and CH3CH2CH2CH3 
B)  Br2 and HI 
C)  HF and CCl4 
D)  CCl4 and Br2 
E)  CCl4 and NH3

Question 13

The phase diagram for carbon dioxide is shown below. What are the phase changes in order as carbon dioxide is heated from -90oC to 50oC, at 1 atm pressure?

Accepted Answer

A)  solid →Gas 
B)  solid →Liquid →Gas 
C)  liquid →Gas 
D)  gas →Liquid →Solid 
E)  gas →Liquid 
A)  solid →Gas 
B)  solid →Liquid →Gas 
C)  liquid →Gas 
D)  gas →Liquid →Solid 
E)  gas →Liquid

Question 14

Ion interaction energies are determined by Coulomb's law: $$E = \left( 2.31 \times 10 ^ { - 19 } J \cdot n m \right) \left( \frac { Q _ { 1 } Q _ { 2 } } { d } \right)$$ 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.

Accepted Answer

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 
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 15

Sublimation 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 16

What structural characteristics must a molecule have in order to hydrogen-bond?

Accepted Answer

A hydrogen atom bond

Question 17

Of all the noble gases, ________ has the weakest intermolecular force and hence the lowest 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 18

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

Accepted Answer

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

Question 19

The aroma from almonds and cherries is due in part to a compound called benzaldehyde. A graph of the natural logarithm of the vapor pressure of benzaldehyde vs. 1/temperature produces a straight line with a slope of -5870.99 K. What is the enthalpy of vaporization of benzaldehyde?

Accepted Answer

A)  +473 kJ/mol 
B)  -47.3 kJ/mol 
C)  +47.3 kJ/mol 
D)  -48.8 kJ/mol 
E)  +48.8 kJ/mol 
A)  +473 kJ/mol 
B)  -47.3 kJ/mol 
C)  +47.3 kJ/mol 
D)  -48.8 kJ/mol 
E)  +48.8 kJ/mol

Question 20

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

Accepted Answer

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

Exam 10: Intermolecular Forces: The Uniqueness of Water

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.)

Which hydride do you predict has the highest boiling point?

CH2F2 has a dipole moment of 1.93 D and a boiling point of -52°C. CH2Cl2 has a dipole moment of 1.60 D and a boiling point of 40°C. Why is the boiling point of dichloromethane so much higher than that of difluoromethane?

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

Which is the dominant interaction between acetone molecules, (CH3)2CO?

On the phase diagram below, identify the normal melting point.

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

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

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?

Which is the dominant interaction that leads to the formation of a hydration sphere in a salt solution?

Would water rise to the same height in a capillary tube made of polyethylene plastic as it does in a glass capillary tube of the same diameter? Polyethylene is a hydrocarbon, and glass is mostly silicon dioxide. Explain.

Indicate which of the following pairs of compounds is most likely to be miscible.

The phase diagram for carbon dioxide is shown below. What are the phase changes in order as carbon dioxide is heated from -90oC to 50oC, at 1 atm pressure?

Sublimation occurs in going from region ________

What structural characteristics must a molecule have in order to hydrogen-bond?

Of all the noble gases, ________ has the weakest intermolecular force and hence the lowest boiling point.

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

The aroma from almonds and cherries is due in part to a compound called benzaldehyde. A graph of the natural logarithm of the vapor pressure of benzaldehyde vs. 1/temperature produces a straight line with a slope of -5870.99 K. What is the enthalpy of vaporization of benzaldehyde?

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

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

CH₂F₂ has a dipole moment of 1.93 D and a boiling point of -52°C. CH₂Cl₂ has a dipole moment of 1.60 D and a boiling point of 40°C. Why is the boiling point of dichloromethane so much higher than that of difluoromethane?

Which is the dominant interaction between acetone molecules, (CH₃)₂CO?

The phase diagram for carbon dioxide is shown below. What are the phase changes in order as carbon dioxide is heated from -90^oC to 50^oC, at 1 atm pressure?