Intensive variable

Definition

An intensive variable is a physical quantity whose value does not depend on the size or extent of the system. Examples include temperature, pressure, and density.

5 Must Know Facts For Your Next Test

1. Intensive variables remain constant when a system is divided into smaller parts.
2. Unlike extensive variables, intensive variables are independent of the amount of substance present.
3. Temperature and pressure are common examples of intensive variables in thermodynamics.
4. The ratio of two extensive variables can produce an intensive variable (e.g., density is mass divided by volume).
5. Intensive variables are essential for characterizing the state of a thermodynamic system.

Review Questions

• What distinguishes an intensive variable from an extensive variable?
• Give two examples of intensive variables commonly used in thermodynamics.
• How can you derive an intensive variable from two extensive variables?

Related terms

Extensive Variable: A physical quantity that depends on the size or extent of the system, such as mass or volume.

Thermodynamic System:

A quantity of matter or a region in space chosen for study in thermodynamics.

\$First Law of Thermodynamics\$: \$\Delta U = Q - W\$, which states that the change in internal energy (\$U\$) of a closed system is equal to the heat (\$Q\$) added to the system minus the work (\$W\$) done by the system.