Helmholtz free energy

Description

The Helmholtz free energy is a thermodynamic potential that measures the “useful” work obtainable from a closed thermodynamic system at a constant temperature. The negative of the difference in the Helmholtz energy is equal to the maximum amount of work that the system can perform in a thermodynamic process in which temperature is held constant. The Helmholtz energy is commonly used for systems held at constant volume. For a system at constant temperature and volume, the Helmholtz energy is minimized at equilibrium.