Helmholtz free energy

							                            Helmholtz free energy

It is difficult to manipulate S and V in the laboratory', but it is far easier to change T
and V. The question is : "What Is the equilibrium condition at constant T, V?"


 For a constant T



The Helmholtz free energy (or simply free energy) defined
The earlier inequality now reads




For infinitesimal reversible transformations, we have

Using the first law, we can reduce this to

Through the Maxwell relation we obtain