entropy

Pronunciation: en′trŏ-pē

Definition: That fraction of heat (energy) content not available for the performance of work, usually because (in a chemical reaction) it has been used to increase the random motion of the atoms or molecules in the system; thus, entropy is a measure of randomness or disorder. Entropy occurs in the Gibbs free energy (G) equation: ΔG = ΔH − TΔS (ΔH, change in enthalpy or heat content; T, absolute temperature; ΔS, change in entropy; ΔG, change in Gibbs free energy).

[G. entropia, a turning toward]

See Also: second law of thermodynamics

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