Helmholtz free energy

Helmholtz free energy is a thermodynamic quantity that measures the useful energy available in a system at constant temperature and volume. It indicates the work that can be done by the system when it reaches equilibrium, while accounting for energy lost as heat due to entropy. Think of it as the portion of a system’s total energy that can be converted into work without changing temperature or volume. Systems naturally tend to minimize their Helmholtz free energy, moving toward a stable state where this available energy is as low as possible.