Helmholtz free energy


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.

Related formulas


AThe Helmholtz energy (J)
UThe internal energy of the system (J)
TThe absolute temperature (K)
SThe entropy (J/K)