Entropy of Irreversible Processes Across a Boundary

Jurgen Michael Honig*, Ross Hoehn
Department of Chemistry, Purdue University, West Lafayette, Indiana, 47907 USA

© 2011 Honig and Hoehn;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to these authors at the Department of Chemistry, Purdue University, West Lafayette, Indiana, 47907 USA; Tel: 765 494 5279; Fax: 765 494 0239; E-mail:


A novel method for determining the entropy associated with irreversible processes has been provided, differing from the conventional theory of irreversible thermodynamics. It permits the direct relation of heat and work transfers in irreversible processes to those in reversible changes, in terms of measurable properties. The same technique is applied to the construction of thermodynamic state functions that are no longer limited to reversible phenomena. The results are then used to construct line integrals for the contribution of irreversible processes to the entropy associated with the flow of heat, work, and matter across a junction. Specific examples are provided to illustrate the procedure; they relate to changes of temperature and volume and to cycling of systems interacting with a reservoir via a thin barrier.

Keywords: Irreversible process/phenomenon, irreversible function of state, quasistatic irreversible processes.