Process function

This article is about the mathematical concept used in thermodynamics. For the engineering indicator, see process variable.

See also: List of thermodynamic properties

A process function, process quantity, or a path function is a physical quantity that describes the transition of a system from an equilibrium state to another equilibrium state. As an example, mechanical work and heat are process quantities because they describe quantitatively the transition between equilibrium states of thermodynamic systems. It depends on the heat done and how the state is reached.

Examples of path functions include work, heat, and distance.

See also

• State function
• Thermodynamics