A thermodynamic analysis begins by deciding what to study and what to treat as its environment. This lesson introduces thermodynamic systems, boundaries, surroundings, and the distinction between open and closed systems. These choices matter because they determine which exchanges of energy and matter must be considered.
A thermodynamic system is the object, substance, or region whose thermodynamic properties are of interest. Everything outside the system is its surroundings or environment. The boundary is the real or imagined surface that separates the system from its surroundings.
All flashcards
What is a thermodynamic system?
It is the object, substance, or region selected for study because its thermodynamic properties are of interest.
What are a boundary and the surroundings?
The boundary separates the system from everything outside it. The surroundings are the environment external to the chosen system.
How does an open system differ from a closed system?
An open system can exchange matter and energy with its surroundings. A closed system cannot exchange matter, although energy may still cross its boundary.
What makes a system isolated?
An isolated system exchanges neither matter nor energy with its surroundings. Perfect isolation is usually an idealization.
What is meant by a macroscopic property?
It is a large-scale property, such as temperature or pressure, that summarizes the average behavior of many microscopic particles.
Quiz questions
What is a state variable in thermodynamics?Answer: A measurable property used to describe a system's condition.
What does an equation of state describe?Answer: A relationship among state variables for a particular system.
Which equation of state applies to an ideal gas?Answer: pV=nRT
How is volume classified when the amount of matter changes at unchanged intensive conditions?Answer: As an extensive variable.
Which of these is an intensive thermodynamic variable?Answer: Pressure.
Based on University Physics Volume 2 by Samuel J. Ling, William Moebs, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.