Question 1

According to the phase diagram shown above,what is the normal melting point (°C)?
A)15
B)25
C)35
D)45
E)55

Accepted Answer

The normal melting point is the temperature at which a substance changes from solid to liquid at 1 atm pressure. According to the phase diagram, this occurs at 15°C.

Question 2

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated.The slope of the E-F segment corresponds to the heat capacity of the ________.
A)liquid-gas
B)solid-gas
C)gas
D)solid
E)liquid

Accepted Answer

The E-F segment of a heating curve represents the phase where the substance is in the gaseous state, and the slope corresponds to the heat capacity of the gas.

Question 3

Molecules with ________ do not generally exhibit liquid-crystalline properties because they lack the rigidity necessary for alignment.
A)both single and double bonds
B)double or triple bonds
C)single, double, and triple bonds
D)only single bonds
E)only single and double bonds

Accepted Answer

Molecules with only single bonds generally do not exhibit liquid-crystalline properties because they lack the rigidity necessary for alignment. The presence of double or triple bonds in a molecule contributes to its rigidity, which is a prerequisite for the formation of liquid crystals. Single bonds allow for more flexibility, making it difficult for the molecules to align in the ordered structures characteristic of liquid crystals.

Question 4

In the ________ liquid crystalline phase,the component molecules exhibit ________ dimensional ordering.
A)nematic, one
B)smectic A, one
C)nematic, two
D)nematic, three
E)smectic B, one

Accepted Answer

In the nematic liquid crystalline phase, the component molecules exhibit one-dimensional ordering. This is a characteristic feature of nematic phase.

Question 5

The phase diagram of a substance is given above.The region that corresponds to the solid phase is ________.
A)w
B)x
C)y
D)z
E)x and y

Accepted Answer

The solid phase is typically found at low temperatures and high pressures, which corresponds to region 'w' in a phase diagram.

Question 6

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated.The slope of the ________ segment corresponds to the heat capacity of the liquid of the substance.
A)AB
B)BC
C)CD
D)DE
E)EF

Accepted Answer

The segment CD represents the heating of the liquid phase, where the temperature increases with added heat, indicating the heat capacity of the liquid.

Question 7

Based on molecular mass and dipole moment of the five compounds in the table below,which should have the highest boiling point? A)CH₃CH₂CH₃ B)CH₃OCH₃ C)CH₃Cl D)CH₃CHO E)CH₃CN

Accepted Answer

The answer of Based on molecular mass and dipole moment...

Question 8

On the phase diagram shown above,segment ________ corresponds to the conditions of temperature and pressure under which the solid and the gas of the substance are in equilibrium.
A)AB
B)AC
C)AD
D)CD
E)BC

Accepted Answer

The answer of On the phase diagram shown above,segment ________...

Question 9

On the phase diagram shown above,the coordinates of point B corresponds to the ________.
A)critical temperature and pressure
B)critical pressure
C)critical temperature
D)boiling point
E)triple point

Accepted Answer

Point B on a phase diagram represents the critical point, which is characterized by the critical temperature and pressure. At this point, the distinction between liquid and gas phases disappears.

Question 10

For a given substance that exhibits liquid-crystalline properties,the transition from solid to liquid-crystal state occurs ________.
A)over a range of temperatures between the melting point of the solid and the boiling point of the liquid
B)at the melting point of the solid
C)over a range of temperatures that includes the melting point of the solid
D)at a well-defined temperature above the melting point of the solid
E)at a well-defined temperature below the melting point of the solid

Accepted Answer

The answer of For a given substance that exhibits liquid-crystalline...

Question 11

________ liquid crystals are colored because the molecular layers are arranged in slightly twisted planes with respect to one another.
A)smectic B
B)cholesteric
C)smectic A
D)smectic C
E)smectic D

Accepted Answer

Cholesteric liquid crystals are colored due to their molecular layers being arranged in slightly twisted planes, which affects how they interact with light, creating the appearance of color.

Question 12

The phase diagram of a substance is shown above.The area labeled ________ indicates the gas phase for the substance.
A)w
B)x
C)y
D)z
E)y and z

Accepted Answer

The gas phase is typically located at high temperatures and low pressures on a phase diagram, which is usually represented by the area labeled "y".

Question 13

On the phase diagram shown above,the coordinates of point ________ correspond to the triple point.
A)A
B)B
C)C
D)D
E)E

Accepted Answer

The answer of On the phase diagram shown above,the coordinates...

Question 14

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated.The slope of the ________ segment corresponds to the heat capacity of the solid.
A)AB
B)BC
C)CD
D)DE
E)EF

Accepted Answer

The slope of segment AB corresponds to the heat capacity of the solid because this segment represents the phase where the substance is being heated as a solid, and its temperature is increasing without a phase change. The slope here indicates how much heat is required to raise the temperature of the solid, which is the definition of heat capacity.

Question 15

The phase diagram of a substance is shown above.The area labeled ________ indicates the solid phase for the substance.
A)w
B)x
C)y
D)z
E)y and z

Accepted Answer

The solid phase is typically found at low temperatures and high pressures, which corresponds to the area labeled "w" in a phase diagram.

Question 16

There are ________ types of smectic liquid-crystalline phases.
A)6
B)5
C)2
D)3
E)4

Accepted Answer

The answer of There are ________ types of smectic liquid-crystalline...

Question 17

The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was heated.The heat flow into the sample in the segment ________ will yield the value of the ΔH_fusion of this substance. A)AB B)BC C)CD D)DE E)EF

Accepted Answer

The segment BC represents the phase transition from solid to liquid (melting) at a constant temperature. The heat flow during this segment corresponds to the enthalpy of fusion (ΔH_fusion) for the substance, as it is the energy required to change the phase from solid to liquid without changing the temperature.

Question 18

According to the phase diagram shown above,what is the normal boiling point (°C)?
A)10
B)20
C)30
D)40
E)50

Accepted Answer

The normal boiling point is the temperature at which the vapor pressure of the liquid is equal to 1 atm. This occurs at the point where the vapor pressure curve intersects the 1 atm pressure line, which is at approximately 40°C in the given phase diagram.

Question 19

The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was heated.The heat flow into the sample in the segment D-E will yield the value of the ________ of this substance. A)ΔH_sub B)ΔH_vap C)ΔH_melting D)ΔH_fusion E)ΔH_rxn

Accepted Answer

The segment D-E on a heating curve typically represents the phase change from liquid to gas, which corresponds to the enthalpy of vaporization (ΔH_vap).

Question 20

What are the common types of smectic liquid-crystalline phases?
A)A, C, and D
B)A only
C)A and C
D)A and D
E)C and D

Accepted Answer

The common types of smectic liquid-crystalline phases are A and C. D is not a common type of smectic phase.

Quiz 11: Liquids and Intermolecular Forces

According to the phase diagram shown above,what is the normal melting point (°C) ?

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated.The slope of the E-F segment corresponds to the heat capacity of the ________.

Molecules with ________ do not generally exhibit liquid-crystalline properties because they lack the rigidity necessary for alignment.

In the liquid crystalline phase,the component molecules exhibit dimensional ordering.

The phase diagram of a substance is given above.The region that corresponds to the solid phase is ________.

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated.The slope of the ________ segment corresponds to the heat capacity of the liquid of the substance.

Based on molecular mass and dipole moment of the five compounds in the table below,which should have the highest boiling point?

On the phase diagram shown above,segment ________ corresponds to the conditions of temperature and pressure under which the solid and the gas of the substance are in equilibrium.

On the phase diagram shown above,the coordinates of point B corresponds to the ________.

For a given substance that exhibits liquid-crystalline properties,the transition from solid to liquid-crystal state occurs ________.

________ liquid crystals are colored because the molecular layers are arranged in slightly twisted planes with respect to one another.

The phase diagram of a substance is shown above.The area labeled ________ indicates the gas phase for the substance.

On the phase diagram shown above,the coordinates of point ________ correspond to the triple point.

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated.The slope of the ________ segment corresponds to the heat capacity of the solid.

The phase diagram of a substance is shown above.The area labeled ________ indicates the solid phase for the substance.

There are ________ types of smectic liquid-crystalline phases.

The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was heated.The heat flow into the sample in the segment ________ will yield the value of the ΔH_fusion of this substance.

According to the phase diagram shown above,what is the normal boiling point (°C) ?

The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was heated.The heat flow into the sample in the segment D-E will yield the value of the ________ of this substance.

What are the common types of smectic liquid-crystalline phases?