State function

Definition

A state function is a property of a system that depends only on its current state and not on the path taken to reach that state. Examples include enthalpy, internal energy, and entropy.

5 Must Know Facts For Your Next Test

1. State functions are path-independent, meaning their values are determined solely by the initial and final states of the system.
2. Enthalpy ($H$) is a common example of a state function in thermochemistry.
3. The change in a state function between two states is represented as $\Delta$ (e.g., $\Delta H$ for enthalpy change).
4. State functions can be added or subtracted to find new state functions (e.g., Gibbs free energy $G = H - TS$).
5. Heat ($q$) and work ($w$) are not state functions because they depend on the specific path taken.

Review Questions

• What distinguishes a state function from other types of functions?
• Why is enthalpy considered a state function?
• Can heat and work be classified as state functions? Why or why not?

Related terms

Enthalpy:

A measure of the total energy of a thermodynamic system, including internal energy and the product of pressure and volume.

Internal Energy: The total energy contained within a system, including kinetic and potential energies at the molecular level.

Entropy:

A measure of the disorder or randomness in a system, which is also a state function.