State functions

Definition

State functions are properties of a system that depend only on the current state of the system, not on the path taken to reach that state. Examples include internal energy, pressure, and temperature.

5 Must Know Facts For Your Next Test

1. State functions are independent of the process used to achieve them.
2. Internal energy (U), enthalpy (H), and entropy (S) are all state functions.
3. Work (W) and heat (Q) are not state functions because they depend on the specific path taken during a process.
4. The change in a state function is zero for any cyclic process that returns to its initial state.
5. State functions are essential for defining equilibrium states in thermodynamics.

Review Questions

• Why are work and heat not considered state functions?
• List three examples of state functions and explain why they qualify as such.
• How does the concept of state functions simplify calculations in thermodynamics?

Related terms

Internal Energy: A measure of the total energy contained within a system, including both kinetic and potential energy at the microscopic level.

Enthalpy: $H = U + PV$, where $H$ is enthalpy, $U$ is internal energy, $P$ is pressure, and $V$ is volume. It represents the total heat content of a system.

Entropy: $S$, a measure of disorder or randomness in a system. Higher entropy indicates greater disorder.