Helmholtz free energy

This page develops the Helmholtz free energy from the point of view of thermal and statistical physics. For applications to chemistry, see work content.

The Helmholtz free energy is a state function of a system defined as

F = U - TS

where F is the Helmholtz free energy in joules,

U is the energy of the system in joules,

T is the temperature in kelvin,

and S is the entropy in joules per kelvin.

Note: in some literature, this quantity is referred to as A.