State variable

Definition

A state variable is a property of a system that depends only on the current state of the system, not on how that state was reached. Examples include temperature, pressure, and volume.

5 Must Know Facts For Your Next Test

1. State variables are path-independent, meaning they do not depend on the process taken to reach a specific state.
2. Temperature and internal energy are examples of state variables in thermodynamics.
3. In calorimetry, the initial and final temperatures are used as state variables to determine heat transfer.
4. State functions can be used to describe equilibrium states in thermodynamic systems.
5. The change in a state variable can be determined by comparing its values at two different states.

Review Questions

• What is a key characteristic that differentiates a state variable from other types of variables?
• Give two examples of state variables commonly used in thermodynamics.
• How do state variables relate to equilibrium states in thermodynamic systems?

Related terms

Heat: The transfer of thermal energy between systems or objects with different temperatures.

Specific Heat: The amount of heat required to change the temperature of one gram of a substance by one degree Celsius.

Calorimetry: \text{The science of measuring the amount of heat transferred to or from a substance during physical or chemical processes.}