Meaning of Free Energy (Gibbs free energy)

[Paulo Bernardo]

Hello everyone, I'm reading some basics of chemistry thermodynamics, and it's hard for me to figure out what is the actual meaning of free energy. could someone please help clarifying this giving specify, real life examples, like applications in mechanical engineering.

Thanks

 

[gleem]

A change in the (i.e.,decrease) in the Gibbs Function, G (free energy) of a system is the work done ( energy freed) in a reversible isothermal-isobaric process exclusive of any pdV work.

The term "free energy" is also applied to the Helmholtz function H whose decrease is the work done by a system in a reversible isothermal process.

Thus G = F - pdV

One should preface free energy with either Gibbs or Helmholtz to avoid confusion.