What is Gibbs free energy?

What is Gibbs free energy?

• A. Energy stored as potential energy.
• B. Total internal energy of a system.
• C. Energy available to do work.
• D. Entropy content of a system.

Answer: (C)

Gibbs free energy is a thermodynamic potential that tells you how much energy in a system can be used to perform useful work when temperature and pressure are held constant. It combines the system’s enthalpy (total heat content) with the energy tied up in entropy, via the relation G = H − TS. In practical terms, the maximum amount of non-expansion work you can obtain from a process at constant temperature and pressure equals the decrease in Gibbs free energy (ΔG). If ΔG is negative, the process can proceed spontaneously; if positive, it tends not to occur without input of energy. This makes Gibbs free energy distinct from the total internal energy (the entire energy content) and from entropy itself (disorder), and it’s different from simply energy stored as potential energy.

Gibbs free energy is a thermodynamic potential that tells you how much energy in a system can be used to perform useful work when temperature and pressure are held constant. It combines the system’s enthalpy (total heat content) with the energy tied up in entropy, via the relation G = H − TS. In practical terms, the maximum amount of non-expansion work you can obtain from a process at constant temperature and pressure equals the decrease in Gibbs free energy (ΔG). If ΔG is negative, the process can proceed spontaneously; if positive, it tends not to occur without input of energy. This makes Gibbs free energy distinct from the total internal energy (the entire energy content) and from entropy itself (disorder), and it’s different from simply energy stored as potential energy.