Gibbs free energy (G) is a value that defines how spontaneous a reaction is, with a negative value meaning the reaction is spontaneous, and a positive value meaning the reaction is nonspontaneous. This value is the combination of enthalpy (H) and entropy (S).

Definition: Gibbs free energy is equal to the enthalpy of the system minus the product of the temperature and entropy. The equation is given as; G = H – TS.

Gibbs Free Energy Example The reaction between sodium chloride and water is considered a spontaneous reaction and will have a negative ΔG Δ G . This is seen in the reaction.

The Gibbs free energy is important in biology research because it enables one to predict the direction of spontaneous change for a system under the constraints of constant temperature and pressure. These constraints generally apply to all living organisms.

Gibbs energy is the capacity of a system to do non-mechanical work and ΔG measures the non- mechanical work done on it. The Gibbs free energy is the maximum amount of non-expansion work that. can be extracted from a closed system; this maximum can be attained only in a completely reversible. process.

The standard Gibbs free energy change, ΔG°, indicates the thermodynamic favorability of a physical or chemical process. When ΔG° < 0, the process is thermodynamically favored. For a given process, the value of ΔG° can be calculated directly from the values of ΔH° and ΔS° using the following equation: ΔG° = ΔH° - TΔS°.