Question 1

When identical particles pack in a simple cubic lattice, there is/are __________ particle(s)  per unit cell.

Accepted Answer

A)  1
B)  2
C)  3
D)  4
E)  8F) None of the above
G) B) and C)

Question 2

Liquid ammonia (boiling point = −33.4°C)  can be used as a refrigerant and heat transfer fluid. How much energy is needed to heat 25.0 g of NH3(l)  from −65.0°C to −12.0°C? 3(l)  from −65.0°C to −12.0°C?   A) 5.5 kJ B) 6.3 kJ C) 39 kJ D) 340 kJ E) 590 kJ" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  5.5 kJ
B)  6.3 kJ
C)  39 kJ
D)  340 kJ
E)  590 kJF) None of the above
G) B) and E)

Question 3

If the solid form of a pure substance is denser than its liquid form, an increase in pressure will cause the melting point to decrease.

Accepted Answer

A) True 
 B)False

Question 4

Which one of the following statements about unit cells and packing in solids is incorrect?

Accepted Answer

A)  In any unit cell of a solid crystal, each face of the cell must have an opposite face which is equal and parallel to it.
B)  The faces of a unit cell must all be at angles of 90° to each other.
C)  The coordination number of atoms in a close packed metal is 12.
D)  The packing efficiency in fcc structures is higher than in bcc structures.
E)  The packing efficiency in fcc and hcp structures is the same.F) A) and C)
G) All of the above

Question 5

What adjective best describes the solid compound IF7?

Accepted Answer

A)  metallic
B)  amorphous
C)  covalent network
D)  molecular
E)  ionicF) None of the above
G) A) and D)

Question 6

Only molecules that do not have dipole moments can experience dispersion forces.

Accepted Answer

A) True 
 B)False

Question 7

Liquid sodium can be used as a heat transfer fluid. Its vapor pressure is 40.0 torr at 633°C and 400.0 torr at 823°C. Calculate its heat of vaporization.

Accepted Answer

A)  43.4 kJ/mol
B)  52.5 kJ/mol
C)  70.6 kJ/mol
D)  1.00 × 10 2 kJ/mol
E)  None of these choices are correct.F) B) and D)
G) C) and E)

Question 8

The energy of a hydrogen bond is greater than that of a typical covalent bond.

Accepted Answer

A) True 
 B)False

Question 9

Examine the following phase diagram and determine what phase exists at point F.

Accepted Answer

A)  Vapor + Liquid
B)  Vapor
C)  Liquid
D)  Solid
E)  Supercritical fluidF) A) and C)
G) A) and D)

Question 10

The strongest intermolecular interactions between ethyl alcohol (CH3CH2OH)  molecules arise from

Accepted Answer

A)  dipole-dipole forces.
B)  London dispersion forces.
C)  hydrogen bonding.
D)  ion-dipole interactions.
E)  carbon-oxygen bonds.F) None of the above
G) A) and B)

Question 11

The normal boiling point of ether is 307.8 K. Calculate the temperature at which its vapor pressure is exactly half of that at its normal boiling point. The heat of vaporization for ether is 26.69 kJ/mol.

Accepted Answer

A)  305 K
B)  302 K
C)  295 K
D)  289 K
E)  281 KF) B) and C)
G) None of the above

Question 12

Select the pair of substances in which the one with the lower vapor pressure at a given temperature is listed first.

Accepted Answer

A)   
B)   
C)   
D)   
E)   F) None of the above
G) A) and C)

Question 13

Polonium crystallizes in the simple cubic lattice. What is the coordination number for Po?

Accepted Answer

A)  3
B)  4
C)  6
D)  8
E)  12F) A) and B)
G) A) and E)

Question 14

Which of the following should have the highest boiling point?

Accepted Answer

A)  CF 4
B)  CCl 4
C)  CBr 4
D)  CI 4
E)  CH 4F) A) and E)
G) A) and B)

Question 15

All gases can be liquefied at room temperature simply by increasing the pressure on the gas.

Accepted Answer

A) True 
 B)False

Question 16

For the solid forms of the following elements, which one is most likely to be of the molecular type?

Accepted Answer

A)  Xe
B)  C
C)  Pb
D)  S
E)  CrF) A) and E)
G) A) and D)

Question 17

Ammonia's unusually high melting point is the result of

Accepted Answer

A)  dipole-dipole forces.
B)  London dispersion forces.
C)  hydrogen bonding.
D)  covalent bonding.
E)  ionic bonding.F) A) and B)
G) B) and D)

Question 18

Which of the following factors contributes to a low viscosity for a liquid?

Accepted Answer

A)  Low temperature
B)  Spherical molecular shape
C)  Hydrogen bonding
D)  High molecular weight
E)  High boiling pointF) A) and D)
G) A) and C)

Question 19

When liquid bromine is cooled to form a solid, which of the following types of solid would it form?

Accepted Answer

A)  atomic
B)  metallic
C)  molecular
D)  ionic
E)  covalent networkF) C) and D)
G) B) and E)

Question 20

The strongest intermolecular interactions between hydrogen sulfide (H2S)  molecules arise from

Accepted Answer

A)  dipole-dipole forces.
B)  London dispersion forces.
C)  hydrogen bonding.
D)  ion-dipole interactions.
E)  disulfide linkages.F) C) and D)
G) A) and E)

Exam 12: Intermolecular Forces: Liquids, Solids, and Phase Changes

Only molecules that do not have dipole moments can experience dispersion forces.

Correct AnswerverifiedShow Answer

Liquid sodium can be used as a heat transfer fluid. Its vapor pressure is 40.0 torr at 633°C and 400.0 torr at 823°C. Calculate its heat of vaporization.

Correct AnswerverifiedShow Answer

If the solid form of a pure substance is denser than its liquid form, an increase in pressure will cause the melting point to decrease.

Correct AnswerverifiedShow Answer

The energy of a hydrogen bond is greater than that of a typical covalent bond.

Correct AnswerverifiedShow Answer

For the solid forms of the following elements, which one is most likely to be of the molecular type?

Correct AnswerverifiedShow Answer

When liquid bromine is cooled to form a solid, which of the following types of solid would it form?

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All gases can be liquefied at room temperature simply by increasing the pressure on the gas.

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Which of the following should have the highest boiling point?

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The strongest intermolecular interactions between ethyl alcohol (CH3CH2OH) molecules arise from

Correct AnswerverifiedShow Answer

The strongest intermolecular interactions between hydrogen sulfide (H2S) molecules arise from

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Polonium crystallizes in the simple cubic lattice. What is the coordination number for Po?

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Ammonia's unusually high melting point is the result of

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What adjective best describes the solid compound IF7?

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Which one of the following statements about unit cells and packing in solids is incorrect?

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Liquid ammonia (boiling point = −33.4°C) can be used as a refrigerant and heat transfer fluid. How much energy is needed to heat 25.0 g of NH3(l) from −65.0°C to −12.0°C?

Correct AnswerverifiedShow Answer

Examine the following phase diagram and determine what phase exists at point F.

Correct AnswerverifiedShow Answer

The normal boiling point of ether is 307.8 K. Calculate the temperature at which its vapor pressure is exactly half of that at its normal boiling point. The heat of vaporization for ether is 26.69 kJ/mol.

Correct AnswerverifiedShow Answer

Which of the following factors contributes to a low viscosity for a liquid?

Correct AnswerverifiedShow Answer

Select the pair of substances in which the one with the lower vapor pressure at a given temperature is listed first.

Correct AnswerverifiedShow Answer

When identical particles pack in a simple cubic lattice, there is/are __________ particle(s) per unit cell.

Correct AnswerverifiedShow Answer

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The strongest intermolecular interactions between ethyl alcohol (CH₃CH₂OH) molecules arise from

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The strongest intermolecular interactions between hydrogen sulfide (H₂S) molecules arise from

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What adjective best describes the solid compound IF₇?

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Liquid ammonia (boiling point = −33.4°C) can be used as a refrigerant and heat transfer fluid. How much energy is needed to heat 25.0 g of NH₃(l) from −65.0°C to −12.0°C?

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