In thermodynamics, thermodynamic entropy (or Clausius entropy) is a conjunctive term used to differentiate between the entropy of classical thermodynamics, particularly as defined by German physicist Rudolf Clausius in 1865, and other more abstract forms of entropy used in niche branches of thermodynamics, e.g. Boltzmann entropy, Gibbs entropy, etc., or as used in non-thermodynamic subjects (such as information theory or mathematics).
Typical examples might include distinguishing between: thermodynamic entropy as compared to statistical entropy; thermodynamic entropy versus internal entropy, such as discussed in nonequilibrium thermodynamics; thermodynamic entropy contrasted with "entropy of surface formation", such as discussed in the movement of molecules in a liquid towards the surface; or as is most often the case, particularly after the publication of American electrical engineer Claude Shannon’s 1948 “Mathematical Theory of Communication”, the contrast between thermodynamic entropy and information entropy (or Shannon entropy), as used in information theory or information theory thermodynamics.
References
1. (a) Harkins, William D. (1919). “The Change of Molecular Kinetic Energy into Molecular Potential Energy: the Entropy Principle and Molecular Association” (thermodynamic entropy vs. entropy of surface formation, pg. 540-41), Proceedings of the National Academy of Sciences of the United States (pgs. 539-57), Vol. 5.
(b) Mortimer, Robert G. (2000). Physical Chemistry (section: The Statistical Entropy and the Thermodynamic Entropy, pg. 118-19). Academic Press.
