Chpt 3 Real Or Ideal Gas Behavior Flashcards
QUESTION
OPTION 1
- What is the van der Waals equation used to describe? (a) Ideal gas behavior (b) Real gas behavior (c) Ideal and real gas behavior (d) Chemical reactions
Answer: b) Real gas behavior
- When do both b and a constants in the van der Waals equation become negligible? (a) When pressure is low (b) When temperature is low (c) When pressure is high (d) When temperature is high
Answer: d) When temperature is high
- What does the term ‘a’ in the van der Waals equation represent? (a) The volume occupied by gas molecules (b) The attractive forces between molecules (c) The total pressure (d) The volume of the gas
Answer: b) The attractive forces between molecules
- What is the role of the critical temperature of a substance? (a) It is the highest temperature at which gas and liquid can exist as separate phases (b) It is the lowest temperature at which gas can exist (c) It is the temperature at which the gas condenses to a liquid (d) It defines the density of the gas
Answer: a) It is the highest temperature at which gas and liquid can exist as separate phases
- What does the critical pressure refer to? (a) The pressure at the critical point where gas and liquid phases become indistinguishable (b) The pressure at which gas liquefies (c) The pressure required for a gas to form a vapor (d) The pressure at low temperatures
Answer: a) The pressure at the critical point where gas and liquid phases become indistinguishable
- At what temperature does the meniscus between gas and liquid phases disappear? (a) At absolute zero (b) At the freezing point (c) At the boiling point (d) At the critical temperature
Answer: d) At the critical temperature
- Which of the following is true about the critical molar volume? (a) It is the molar volume at standard temperature and pressure (b) It is the molar volume at the critical temperature and pressure (c) It is the volume of gas at high temperatures (d) It is the volume of gas at very low pressures
Answer: b) It is the molar volume at the critical temperature and pressure
- What happens to the compressibility factor Z when a gas is more compressible than an ideal gas? (a) Z is constant (b) Z > 1 (c) Z = 1 (d) Z < 1
Answer: d) Z < 1
- What causes the positive deviation from ideal gas behavior in real gases? (a) Intermolecular attraction forces (b) Decreased volume of molecules at low temperature (c) Increased volume of molecules at high pressure (d) No molecular volume
Answer: c) Increased volume of molecules at high pressure
- In the van der Waals equation, what does the constant b account for? (a) Intermolecular attractive forces (b) Pressure of the gas (c) Volume occupied by gas molecules (d) Temperature of the gas
Answer: c) Volume occupied by gas molecules
- What happens to the behavior of gases at high pressures and low temperatures? (a) They behave ideally (b) They become more compressible (c) They show significant deviations from ideal gas behavior (d) They follow Boyle’s law perfectly
Answer: c) They show significant deviations from ideal gas behavior
- What is the importance of the horizontal lines in carbon dioxide isotherms? (a) They show the transition of gas into a vapor (b) They represent the critical point (c) They represent the maximum temperature for a gas (d) They indicate the condensation of gas into liquid
Answer: d) They indicate the condensation of gas into liquid
- How is the molar volume of a gas affected by intermolecular attractions? (a) It remains constant (b) It decreases with stronger attractions (c) It increases with stronger attractions (d) It is unaffected by intermolecular forces
Answer: b) It decreases with stronger attractions
- Which of the following gases has a high critical temperature? (a) N₂ (b) CO₂ (c) He (d) H₂O
Answer: d) H₂O
- What is the equation for the excluded volume in the van der Waals equation? (a) (4/3)πr³ (b) πr² (c) (2/3)πr³ (d) 4πr²
Answer: a) (4/3)πr³
- What happens in the two-phase region of the pressure-volume diagram near the critical temperature? (a) Only vapor exists (b) Gas phase becomes dominant (c) Liquid phase becomes dominant (d) Gas and liquid phases exist together
Answer: d) Gas and liquid phases exist together
- What does a gas in equilibrium with its corresponding liquid phase refer to? (a) A supercritical fluid (b) A vapor (c) A pure substance (d) An ideal gas
Answer: b) A vapor
- What defines the critical state of a substance? (a) The temperature at which gas becomes a solid (b) The point at which the gas condenses (c) The point at which gas and liquid phases become indistinguishable (d) The temperature at which the gas vaporizes
Answer: c) The point at which gas and liquid phases become indistinguishable
- What is the van der Waals constant ‘a’ related to? (a) The molecular weight of the gas (b) The temperature of the gas (c) The intermolecular attractive forces (d) The volume of molecules
Answer: c) The intermolecular attractive forces
- Which of the following factors is most important for gas liquefaction at low temperatures? (a) High molecular volume (b) High pressure (c) High temperature (d) Attractive forces between molecules
Answer: d) Attractive forces between molecules
- What is the significance of the van der Waals equation compared to the ideal gas law? (a) It accounts for molecular volume and intermolecular attraction (b) It assumes ideal gas behavior (c) It simplifies gas behavior at low temperatures (d) It only accounts for temperature
Answer: a) It accounts for molecular volume and intermolecular attraction