Deck 10: Solids, Liquids, and Phase Transitions

Question 1

The density of a gas is typically

A) 1000 times smaller than a liquid.
B) 10 times smaller than a liquid.
C) approximately the same as a liquid.
D) 10 times greater than a liquid.
E) 1000 times greater than a liquid.

Answer 1

A

Question 2

The potential energy of a molecule at the surface of a liquid is

A) higher than that of a molecule in the bulk.
B) lower than that of a molecule in the bulk.
C) exactly the same as that of a molecule in the bulk.
D) higher or lower depending on the liquid.
E) higher or lower depending on the pressure.

Answer 2

A

Question 3

The thermal expansion coefficient of most liquids is

A) larger than that for most solids.
B) larger than that for most gases.
C) smaller than that for most solids.
D) smaller than that for most gases.
E) b & c
F) a & d

Answer 3

F

Question 4

Which has the highest vapor pressure at room temperature?

A) methanol
B) ethanol
C) propanol
D) butanol
E) there is no way to predict

Question 5

Which do you predict will have the largest intermolecular attraction F₂, Cl₂, Br₂, I₂?

A) F₂
B) Cl₂
C) Br₂
D) I₂
E) they will all be the same

Question 6

What types of intermolecular forces would you expect to find in CHCl₃?

A) dispersion
B) dipole-dipole
C) hydrogen bonding
D) a & b
E) all of the above

Question 7

Generally if a liquid has stronger intermolecular attractions it will have

A) a higher viscosity.
B) a higher vapor pressure.
C) a higher boiling point.
D) a & b
E) b & c
F) a & c
G) all of the above

Question 8

Rank the following in order of increasing boiling point.
CHCl₃, Ne, H₂O, MgO

A) CHCl₃, Ne, H₂O, MgO
B) MgO, Ne, H₂O, CHCl₃
C) Ne, H₂O, MgO, CHCl₃
D) Ne, CHCl₃, H₂O, MgO
E) MgO, CHCl₃, H₂O, Ne

Question 9

The boiling point of CCl₄ is slightly higher than that of CHCl₃. The boiling point of CHF₃ is significantly higher than CF₄. Why is this?

A) The dipole of CHF₃ is larger than that of CHCl₃.
B) The dipole of CHF₃ is smaller than that of CHCl₃.
C) The dispersion forces are larger in CF₄ than CCl₄.
D) The dispersion forces are larger in CF₄ than CCl₄.
E) b & c
F) a & d

Question 10

The vapor pressure of methanol (CH₃OH) at 25°C is 93.3 Torr. If 10 g of methanol is placed into an evacuated 10 L container at a constant temperature of 25°C, what is the final pressure in the container?

A) 58.1 Torr
B) 93.3 Torr
C) 376 Torr
D) 1 atm
E) none of the above

Question 11

The vapor pressure of methanol (CH₃OH) at 25°C is 93.3 Torr. If 1 g of methanol is placed into an evacuated 10 L container at a constant temperature of 25°C, what is the final pressure in the container?

A) 58.1 Torr
B) 93.3 Torr
C) 376 Torr
D) 1 atm
E) none of the above

Question 12

At 20°C the vapor pressure of dry ice is 56.5 atm. If 100 g of dry ice is place in an evacuated 0.5 L chamber at a constant temperature of 20°C, how many grams of solid will sublime?

A) 0.0872 g
B) 10.1 g
C) 28.1 g
D) 51.7 g
E) 100 g

Question 13

At 20°C water has a vapor pressure of 0.0231 atm. If you bubble air through a container of water and collect 1 L of it at a total pressure of 1 atm, how many grams of water are in your sample of air (you can assume it is saturated)?

A) 9.6×10^-4
B) 3.0×10^-4
C) 3.0×10^-3
D) 1.1×10^-2
E) 1.7×10^-2

Question 14

A liquid kinetically trapped below its freezing temperature is called a

A) glassy liquid.
B) condensed liquid.
C) fluid liquid.
D) supercooled liquid.
E) frozen liquid.

Question 15

Which of the following is true for a liquid at its equilibrium vapor pressure?

A) the rate of evaporation exceeds that of condensation.
B) the rate of condensation exceeds that of evaporation.
C) the rate of condensation and evaporation are the same.
D) the system is neither evaporating nor condensing.
E) the system is at the critical point.

Question 16

A supercritical fluid has a density that

A) is lower than a liquid.
B) is lower than a gas.
C) is higher than a liquid.
D) is higher than a gas.
E) can be varied from gas-like to liquid-like.

Question 17

At the triple point

A) solid, liquid, and gas are all in equilibrium.
B) the vapor pressure of the solid is equal to the vapor pressure of the liquid.
C) the rate of sublimation is equal to the rate of evaporation.
D) a & b
E) all of the above

Question 18

For the following phase diagram the area labeled IV is

A) gas
B) liquid
C) solid
D) super critical fluid
E) supercooled liquid

Question 19

The process of a solid converting directly to a gas is called

A) evaporation
B) condensation
C) deposition
D) sublimation
E) transformation

Question 20

Given the phase diagram below, at 200K and a pressure of 150 atm. What phase(s) is (are) present?

A) gas
B) liquid
C) solid
D) liquid and solid
E) gas and liquid

Question 21

The triple point of a compound is at 38.2°C and a pressure of 0.75 atm. A gaseous sample of the substance is held at a constant pressure of 0.79 atm. Initially the sample is at 50°C and is slowly cooled until it is -25°C. What if any phase transitions occur?

A) condensation
B) deposition
C) condensation followed by freezing
D) simultaneous condensation and freezing
E) none of the above

Question 22

For a given substance, the vapor pressure of a liquid can never be

A) equal to the pressure at the triple point.
B) equal to the critical temperature.
C) lower than the vapor pressure of the solid.
D) higher than the vapor pressure of the solid.
E) greater than 1 atm.

Question 23

Which do you think will have the highest surface tension?

A) water
B) liquid N₂
C) CCl₄
D) CHCl₃
E) molten NaCl

Question 24

Which do you think has a higher boiling point, n-butanol or tert-butanol?

A) n-butanol because it forms stronger hydrogen bonds.
B) tert-butanol because it forms stronger hydrogen bonds.
C) n-butanol because the linear molecule allows for greater dispersion forces.
D) tert-butanol because the tetrahedral molecule allows for greater dispersion forces.
E) they will be exactly the same.

Question 25

In the phase diagram of water increasing pressure leads to lower melting temperatures.

A) this is true for all compounds
B) this is true for all polar compounds
C) this is true for all hydrogen bonding compounds
D) this is true for compounds with solid phases that are less dense than their liquid phases
E) this is true only for H₂O, HF, and NH₃

Question 26

Dipole-dipole forces are

A) larger than ion-ion forces.
B) about the same as all ion-ion forces.
C) much smaller than ion-ion forces.
D) between the force for °1 ions and °2 ions.
E) about a factor of two smaller the attraction of °1 ions.

Question 27

While many solids are crystalline with a well ordered structure of molecules, glasses are amorphous solids in which the structure of the molecules is random. How is a glass different from a liquid?

A) The glass will have a lower diffusion coefficient.
B) The glass will be rigid.
C) The glass will be more compressible.
D) a & b
E) all of the above

Question 28

Arrange the follow in order of increasing boiling point: H₂O, H₂S, H₂Se, H₂Te

A) H₂O, H₂S, H₂Se, H₂Te
B) H₂Te, H₂Se, H₂S, H₂O
C) H₂O, H₂Te, H₂Se, H₂S
D) H₂S, H₂Se, H₂Te, H₂O
E) H₂S, H₂Se, H₂O, H₂Te

Question 29

The critical temperature for methanol is 512.6 K and the critical pressure is 81 bar. If a sample starts at a temperature of 590 K and a pressure of 45.3 bar and is cooled at constant pressure to a temperature of 512.6 K, what if any, phase transition are observed?

A) condensation
B) evaporation
C) condensation followed by evaporation
D) there are no phase transitions

Question 30

The critical temperature for cyclohexane is 553.5 K and the critical pressure is 40.7 bar. A sample of cyclohexane at a temperature of 532 K and a pressure of 40.7 is

A) a gas
B) a liquid
C) a super critical fluid
D) a super heated fluid
E) a super heated vapor

Question 31

The process of a gas converting directly to a solid is

A) evaporation
B) condensation
C) sublimation
D) deposition
E) freezing

Question 32

Which of the following is the most polarizable?

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

Question 33

Based on intermolecular forces, which organic compound should have the highest boiling point?

A) Propane
B) Dimethyl ketone (acetone)
C) Ethanol
D) Propanol
E) Hexane