Words (or words that have the same definition) The definition is case sensitive (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] (Optional) Caption for Image (Optional) External or Internal Link (Optional) Source for Definition (Eg. "Genetic, Hereditary, DNA ...") (Eg. "Relating to genes or heredity") NaN The infamous double helix https://bio.libretexts.org/ CC-BY-SA; Delmar Larsen Word(s) Definition Image Caption Link Source entropy (S) state function that is a measure of the matter and/or energy dispersal within a system, determined by the number of system microstates; often described as a measure of the disorder of the system NaN NaN NaN NaN Gibbs free energy change (G) thermodynamic property defined in terms of system enthalpy and entropy; all spontaneous processes involve a decrease in G NaN NaN NaN NaN microstate possible configuration or arrangement of matter and energy within a system NaN NaN NaN NaN nonspontaneous process process that requires continual input of energy from an external source NaN NaN NaN NaN reversible process process that takes place so slowly as to be capable of reversing direction in response to an infinitesimally small change in conditions; hypothetical construct that can only be approximated by real processes NaN NaN NaN NaN second law of thermodynamics all spontaneous processes involve an increase in the entropy of the universe NaN NaN NaN NaN spontaneous change process that takes place without a continuous input of energy from an external source NaN NaN NaN NaN standard entropy (S°) entropy for one mole of a substance at 1 bar pressure; tabulated values are usually determined at 298.15 K NaN NaN NaN NaN standard entropy change (ΔS°) change in entropy for a reaction calculated using the standard entropies NaN NaN NaN NaN standard free energy change (ΔG°) change in free energy for a process occurring under standard conditions (1 bar pressure for gases, 1 M concentration for solutions) NaN NaN NaN NaN standard free energy of formation change in free energy accompanying the formation of one mole of substance from its elements in their standard states NaN NaN NaN NaN third law of thermodynamics entropy of a perfect crystal at absolute zero (0 K) is zero NaN NaN NaN NaN