Chot 4 Phase Equilibra Flashcards
1
Q
QUESTION
A
OPTION 1
2
Q
- What is the process called when a solid changes directly into vapor without passing through the liquid phase? (A. Condensation B. Sublimation C. Evaporation D. Crystallization)
A
Answer: B. Sublimation
3
Q
- During which process is heat added to overcome intermolecular forces without changing temperature? (A. Freezing B. Melting C. Condensation D. Crystallization)
A
Answer: B. Melting
4
Q
- What is the reverse of the heating curve of a system? (A. Evaporation curve B. Cooling curve C. Phase diagram D. Sublimation curve)
A
Answer: B. Cooling curve
5
Q
- Above what temperature is a gas unable to liquefy regardless of pressure? (A. Freezing temperature B. Critical temperature C. Boiling temperature D. Melting temperature)
A
Answer: B. Critical temperature
6
Q
- Which of the following gases has a critical temperature of -119°C? (A. Nitrogen B. Oxygen C. Carbon dioxide D. Helium)
A
Answer: A. Nitrogen
7
Q
- What is the principle of liquefaction in the Linde Process? (A. Sublimation B. Free expansion cooling C. Isothermal expansion D. Adiabatic heating)
A
Answer: B. Free expansion cooling
8
Q
- What is the molar latent heat of vaporization? (A. Heat required to vaporize one mole of a liquid B. Heat required to cool one mole of vapor C. Heat required to solidify one mole of liquid D. Heat required to compress one mole of vapor)
A
Answer: A. Heat required to vaporize one mole of a liquid
9
Q
- What happens during evaporation in an open vessel? (A. Molecules condense on the vessel walls B. Molecules diffuse away until the liquid disappears C. Liquid solidifies due to cooling D. Molecules gain heat and sink)
A
Answer: B. Molecules diffuse away until the liquid disappears
10
Q
- What occurs at dynamic equilibrium in a closed system? (A. Vapors escape continuously B. Molecules only evaporate, not condense C. The rate of evaporation equals the rate of condensation D. The liquid freezes completely)
A
Answer: C. The rate of evaporation equals the rate of condensation
11
Q
- What is a characteristic property of a liquid at a given temperature? (A. Latent heat B. Boiling point C. Equilibrium vapor pressure D. Freezing point)
A
Answer: C. Equilibrium vapor pressure
12
Q
- What promotes the liquefaction of a gas? (A. Low pressure and high temperature B. High pressure and low temperature C. High pressure and high temperature D. Low pressure and low temperature)
A
Answer: B. High pressure and low temperature
13
Q
- Which property of a liquid determines its volatility? (A. Specific heat capacity B. Molar mass C. Equilibrium vapor pressure D. Density)
A
Answer: C. Equilibrium vapor pressure
14
Q
- What is the phase change from liquid to vapor called? (A. Freezing B. Vaporization C. Sublimation D. Melting)
A
Answer: B. Vaporization
15
Q
- Which substance has a critical temperature of 374°C? (A. Water B. Nitrogen C. Sulfur dioxide D. Carbon dioxide)
A
Answer: A. Water
16
Q
- What cooling method involves expansion against a pressure? (A. Refrigeration B. External work cooling C. Adiabatic cooling D. Free expansion cooling)
A
Answer: B. External work cooling
17
Q
- Which gas does not cool on expansion at room temperature? (A. Carbon dioxide B. Nitrogen C. Hydrogen D. Oxygen)
A
Answer: C. Hydrogen
18
Q
- What prevents superheating during boiling? (A. Stirring the liquid vigorously B. Decreasing pressure quickly C. Introducing porous materials D. Increasing temperature rapidly)
A
Answer: A. Stirring the liquid vigorously
19
Q
- What type of liquid escapes faster due to weaker intermolecular forces? (A. Volatile liquids B. Non-volatile liquids C. Saturated liquids D. Supercooled liquids)
A
Answer: A. Volatile liquids
20
Q
- Which gas has a critical pressure of 12.8 atm? (A. Oxygen B. Nitrogen C. Hydrogen D. Helium)
A
Answer: A. Oxygen
21
Q
- Which phase change involves a gas turning into a solid? (A. Deposition B. Vaporization C. Sublimation D. Crystallization)
A
Answer: A. Deposition
22
Q
- What is the temperature below which a gas cools upon expansion? (A. Freezing point B. Inversion temperature C. Boiling point D. Critical temperature)
A
Answer: B. Inversion temperature
23
Q
- What does the term “free expansion” mean? (A. Isothermal compression B. Expansion with temperature increase C. Expansion against a vacuum D. Expansion against atmospheric pressure)
A
Answer: C. Expansion against a vacuum
24
Q
- Which cooling method is not influenced by external work? (A. Free expansion B. Adiabatic expansion C. Refrigeration cooling D. Compression cooling)
A
Answer: A. Free expansion
25
Q
- What is required for dynamic equilibrium in a closed container? (A. Equal rates of evaporation and condensation B. Equal rates of freezing and melting C. Continuous cooling D. Constant increase in vapor pressure)
A
Answer: A. Equal rates of evaporation and condensation
26
Q
- What describes liquids as practically incompressible? (A. They are completely solidified B. They lack intermolecular forces C. They have high vapor pressure D. They retain a fixed volume)
A
Answer: D. They retain a fixed volume
27
Q
- What term is used for the pressure exerted by a liquid’s vapor at equilibrium? (A. Critical pressure B. Atmospheric pressure C. Vapor pressure D. Osmotic pressure)
A
Answer: C. Vapor pressure
28
Q
- At what point can a gas not liquefy regardless of pressure? (A. Below the freezing point B. At room temperature C. Above the critical temperature D. Below the boiling point)
A
Answer: C. Above the critical temperature
29
Q
- What is the heat needed to evaporate 50g of ethanol if its molar latent heat is 39.2 kJ/mol? (A. 46.00 kJ B. 42.61 kJ C. 50.00 kJ D. 39.20 kJ)
A
Answer: A. 46.00 kJ
30
Q
- What happens to a liquid’s temperature as it evaporates? (A. It drops B. It remains constant C. It increases D. It oscillates)
A
Answer: A. It drops
31
Q
- Which phenomenon occurs when gas molecules coalesce into a liquid at low temperature? (A. Freezing B. Liquefaction C. Sublimation D. Evaporation)
A
Answer: B. Liquefaction
32
Q
- (What is the process called when a solid changes directly into vapor without passing through the liquid phase? A. Condensation B. Sublimation C. Evaporation D. Crystallization)
A
Answer: B. Sublimation
33
Q
- (During which process is heat added to overcome intermolecular forces without changing temperature? A. Freezing B. Melting C. Condensation D. Crystallization)
A
Answer: B. Melting
34
Q
- (What is the reverse of the heating curve of a system? A. Evaporation curve B. Cooling curve C. Phase diagram D. Sublimation curve)
A
Answer: B. Cooling curve
35
Q
- (Above what temperature is a gas unable to liquefy regardless of pressure? A. Freezing temperature B. Critical temperature C. Boiling temperature D. Melting temperature)
A
Answer: B. Critical temperature
36
Q
- (Which of the following gases has a critical temperature of -119°C? A. Nitrogen B. Oxygen C. Carbon dioxide D. Helium)
A
Answer: A. Nitrogen
37
Q
- (What is the principle of liquefaction in the Linde Process? A. Sublimation B. Free expansion cooling C. Isothermal expansion D. Adiabatic heating)
A
Answer: B. Free expansion cooling
38
Q
- (What is the molar latent heat of vaporization? A. Heat required to vaporize one mole of a liquid B. Heat required to cool one mole of vapor C. Heat required to solidify one mole of liquid D. Heat required to compress one mole of vapor)
A
Answer: A. Heat required to vaporize one mole of a liquid
39
Q
- (What happens during evaporation in an open vessel? A. Molecules condense on the vessel walls B. Molecules diffuse away until the liquid disappears C. Liquid solidifies due to cooling D. Molecules gain heat and sink)
A
Answer: B. Molecules diffuse away until the liquid disappears
40
Q
- (What occurs at dynamic equilibrium in a closed system? A. Vapors escape continuously B. Molecules only evaporate, not condense C. The rate of evaporation equals the rate of condensation D. The liquid freezes completely)
A
Answer: C. The rate of evaporation equals the rate of condensation
41
Q
- (What is a characteristic property of a liquid at a given temperature? A. Latent heat B. Boiling point C. Equilibrium vapor pressure D. Freezing point)
A
Answer: C. Equilibrium vapor pressure
42
Q
- (What promotes the liquefaction of a gas? A. Low pressure and high temperature B. High pressure and low temperature C. High pressure and high temperature D. Low pressure and low temperature)
A
Answer: B. High pressure and low temperature
43
Q
- (Which property of a liquid determines its volatility? A. Specific heat capacity B. Molar mass C. Equilibrium vapor pressure D. Density)
A
Answer: C. Equilibrium vapor pressure
44
Q
- (What is the phase change from liquid to vapor called? A. Freezing B. Vaporization C. Sublimation D. Melting)
A
Answer: B. Vaporization
45
Q
- (Which substance has a critical temperature of 374°C? A. Water B. Nitrogen C. Sulfur dioxide D. Carbon dioxide)
A
Answer: A. Water
46
Q
- (What cooling method involves expansion against a pressure? A. Refrigeration B. External work cooling C. Adiabatic cooling D. Free expansion cooling)
A
Answer: B. External work cooling
47
Q
- (Which gas does not cool on expansion at room temperature? A. Carbon dioxide B. Nitrogen C. Hydrogen D. Oxygen)
A
Answer: C. Hydrogen
48
Q
- (What prevents superheating during boiling? A. Stirring the liquid vigorously B. Decreasing pressure quickly C. Introducing porous materials D. Increasing temperature rapidly)
A
Answer: A. Stirring the liquid vigorously
49
Q
- (What type of liquid escapes faster due to weaker intermolecular forces? A. Volatile liquids B. Non-volatile liquids C. Saturated liquids D. Supercooled liquids)
A
Answer: A. Volatile liquids
50
Q
- (Which gas has a critical pressure of 12.8 atm? A. Oxygen B. Nitrogen C. Hydrogen D. Helium)
A
Answer: A. Oxygen
51
Q
- (Which phase change involves a gas turning into a solid? A. Deposition B. Vaporization C. Sublimation D. Crystallization)
A
Answer: A. Deposition
52
Q
- (What is the temperature below which a gas cools upon expansion? A. Inversion temperature B. Freezing point C. Boiling point D. Critical temperature)
A
Answer: A. Inversion temperature
53
Q
- (What does the term “free expansion” mean? A. Isothermal compression B. Expansion with temperature increase C. Expansion against a vacuum D. Expansion against atmospheric pressure)
A
Answer: C. Expansion against a vacuum
54
Q
- (Which cooling method is not influenced by external work? A. Free expansion B. Adiabatic expansion C. Refrigeration cooling D. Compression cooling)
A
Answer: A. Free expansion
55
Q
- (What is required for dynamic equilibrium in a closed container? A. Equal rates of evaporation and condensation B. Equal rates of freezing and melting C. Continuous cooling D. Constant increase in vapor pressure)
A
Answer: A. Equal rates of evaporation and condensation
56
Q
- (What describes liquids as practically incompressible? A. They are completely solidified B. They lack intermolecular forces C. They have high vapor pressure D. They retain a fixed volume)
A
Answer: D. They retain a fixed volume
57
Q
- (What term is used for the pressure exerted by a liquid’s vapor at equilibrium? A. Critical pressure B. Atmospheric pressure C. Vapor pressure D. Osmotic pressure)
A
Answer: C. Vapor pressure
58
Q
- (At what point can a gas not liquefy regardless of pressure? A. Below the freezing point B. At room temperature C. Above the critical temperature D. Below the boiling point)
A
Answer: C. Above the critical temperature
59
Q
- (What is the heat needed to evaporate 50g of ethanol if its molar latent heat is 39.2 kJ/mol? A. 46.00 kJ B. 42.61 kJ C. 50.00 kJ D. 39.20 kJ)
A
Answer: A. 46.00 kJ
60
Q
- (What happens to a liquid’s temperature as it evaporates? A. It drops B. It remains constant C. It increases D. It oscillates)
A
Answer: A. It drops
61
Q
- (Which phenomenon occurs when gas molecules coalesce into a liquid at low temperature? A. Liquefaction B. Freezing C. Sublimation D. Evaporation)
A
Answer: A. Liquefaction
