Podcast
Questions and Answers
What does the constant Ru represent in thermodynamic equations?
What does the constant Ru represent in thermodynamic equations?
How is the molar mass of a substance defined?
How is the molar mass of a substance defined?
Which equation represents the ideal gas law for a closed system?
Which equation represents the ideal gas law for a closed system?
Under what conditions can water vapor be treated as an ideal gas?
Under what conditions can water vapor be treated as an ideal gas?
Signup and view all the answers
In the ideal gas equation, which variable represents the mass of the substance?
In the ideal gas equation, which variable represents the mass of the substance?
Signup and view all the answers
What characterizes an ideal gas according to the definition provided?
What characterizes an ideal gas according to the definition provided?
Signup and view all the answers
Which law states that the pressure of a gas is inversely proportional to its volume?
Which law states that the pressure of a gas is inversely proportional to its volume?
Signup and view all the answers
Under what conditions does a gas behave as an ideal gas?
Under what conditions does a gas behave as an ideal gas?
Signup and view all the answers
What does the gas constant R represent in the ideal gas equation?
What does the gas constant R represent in the ideal gas equation?
Signup and view all the answers
Which statement about the ideal-gas equation of state is false?
Which statement about the ideal-gas equation of state is false?
Signup and view all the answers
Study Notes
Gas Constant
- The gas constant (R) is different for each gas and is determined by the universal gas constant (Ru) and molar mass (M)
- Ru (universal gas constant) is the same for all substances and its value is 8314 J/kg.K
- R = Ru/M
- Molar mass is the mass of one mole (gmol) of a substance in grams, or the mass of one kmol (kgmol) in kilograms
Ideal Gas Equation of State
- The ideal gas equation of state is Pv = RT
- P is pressure, v is specific volume or volume per unit mass, R is the gas constant and T is temperature.
- There are two other equations of state for ideal gas:
- PV = mR*T (m is the mass of the substance), and
- PV = NRu*T (N is the mole number)
- In a closed system, the ideal gas equation of state can be used to find the relationship between two states:
- P1V1/T1 = P2V2/T2
- This relation is applicable when the working fluid is an ideal gas and the mass is constant.
What is an Ideal Gas?
- An ideal gas is a model substance of infinitely small particles (point masses) that completely fill a defined space and do not interact
- Air, nitrogen, oxygen, carbon dioxide and argon are common examples of ideal gases
What is the Equation of State?
- An equation of state is an equation that relates the pressure, temperature, and specific volume of a substance
- The ideal-gas equation of state predicts the P-v-T behavior of a gas quite accurately within some properly selected region
Compressibility Factor [Z}
- The compressibility factor (Z) is a correction factor that measures the deviation from the ideal gas behavior.
- Z = 1 for an ideal gas, and Z can be greater than or less than 1 for real gases.
- The farther away Z is from unity, the more the gas deviates from ideal-gas behavior.
- Z can be determined using reduced temperature (TR) and reduced pressure (PR)
- TR = T/Tcr, where Tcr is the critical temperature
- PR = P/Pcr, where Pcr is the critical pressure
At what pressures/temperatures can water vapor be approximated as an ideal gas?
- Water vapor can be approximated as an ideal gas at pressures below 10 kPa regardless of its temperature.
Compressibility Factor Chart
- There is a compressibility factor chart available that can be used to determine Z
- At low pressures (PR < 2), ideal-gas behavior can be assumed with good accuracy regardless of the pressure
Ideal Gas Behavior Deviation in Water Vapor
- The deviation of water vapor from ideal-gas behavior is greatest in the vicinity of the critical point.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
