The Rectified Second Law of Thermodynamics

TL;DR

This paper introduces a rectified second law of thermodynamics that allows for the quantification of excess entropy produced by irreversible processes, enabling experimental measurement similar to the first law.

Contribution

It combines equilibrium thermodynamics with Jarzynski's theorem to formulate a new second law that quantifies excess entropy in irreversible processes, especially for QSI processes.

Findings

Derived a general form of the rectified second law.

Applied the law to quantify entropy in RNA unfolding.

Demonstrated experimental measurement of excess entropy.

Abstract

Equilibrium thermodynamics is combined with Jarzynski's irreversible work theorem to quantify the excess entropy produced by irreversible processes. The resulting rectified form of the second law parallels the first law, in the sense that it facilitates the experimental measurement of excess entropy changes resulting from irreversible work and heat exchanges, just as the first law quantifies energy changes produced by either reversible or irreversible work and heat exchanges. The general form of the rectified second law is further applied to a sub-class of quasi-static irreverisble (QSI) processes, for which all the thermodynamic functions of both the system and surroundings remain continuously well-defined, thus facilitating excess entropy measurements by integrating exact differential functions along QSI paths. The results are illustrated by calculating the mechanical and thermal excess entropy produced by the irreversible unfolding of an RNA molecule.