Boundary

Definition

A boundary is a real or imaginary surface that separates a thermodynamic system from its surroundings. It defines the limits within which the system's properties are analyzed.

5 Must Know Facts For Your Next Test

1. Boundaries can be fixed or movable, depending on whether they allow for volume changes in the system.
2. They can be diathermal, allowing heat transfer, or adiabatic, preventing heat transfer.
3. The type of boundary affects how energy and matter exchange between the system and its surroundings.
4. In thermodynamics, boundaries help define open systems (exchange both energy and matter), closed systems (exchange only energy), and isolated systems (exchange neither energy nor matter).
5. Understanding boundaries is crucial for applying the First Law of Thermodynamics to calculate work done by or on the system.

Review Questions

• What are the different types of boundaries in thermodynamic systems?
• How does a diathermal boundary differ from an adiabatic boundary?
• Why is it important to understand boundaries when applying the First Law of Thermodynamics?

Related terms

System: A specified portion of the universe chosen for analysis in thermodynamics, separated from its surroundings by boundaries.

Surroundings: Everything external to the system that can interact with it through exchanges of energy or matter.

First Law of Thermodynamics:

$\Delta U = Q - W$, where $\Delta U$ is the change in internal energy of a system, $Q$ is heat added to the system, and $W$ is work done by the system.