What is free energy?

Free energy refers to the portion of a system's energy that is available to perform work at constant temperature and pressure. This concept is crucial in thermodynamics and biochemistry because it allows us to predict the spontaneity of reactions and the efficiency of energy transfer in biological systems.

When considering the definition of free energy, it is important to note that it considers both the enthalpy (total heat content) and the entropy (degree of disorder) of the system. The Gibbs Free Energy, which is commonly used in biological contexts, defines this available energy in relation to temperature and entropy changes.

In contrast to choices that refer to energy that is either unavailable for work, total energy, or energy released during reactions, free energy specifically highlights the capacity to perform work. Understanding free energy helps in comprehending metabolic processes, enzyme functions, and the energetics of cellular respiration and photosynthesis, as these phenomena depend heavily on the availability of energy for work.