On determining absolute entropy without quantum theory or the third law of thermodynamics

Journal article

Abstract:: We employ classical thermodynamics to gain information about absolute entropy, without recourse to statistical methods, quantum mechanics or the third law of thermodynamics. The Gibbs-Duhem equation yields various simple methods to determine the absolute entropy of a fluid. We also study the entropy of an ideal gas and the ionization of a plasma in thermal equilibrium. A single measurement of the degree of ionization can be used to determine an unknown constant in the entropy equation, and thus determine the absolute entropy of a gas. It follows from all these examples that the value of entropy at absolute zero temperature does not need to be assigned by postulate, but can be deduced empirically.

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Keywords:: third law of thermodynamics

Saha equation

SBTMR

entropy

Gibbs-Duhem equation

Sackur-Tetrode equation
Pubs id:: pubs:623974
UUID:: uuid:62fd40b5-dad8-41bf-8923-840f4dec0f0b
Local pid:: pubs:623974
Source identifiers:: 623974
Deposit date:: 2017-10-04

Copyright holder:: IOP Publishing Ltd and Deutsche Physikalische Gesellschaft
Notes:: © 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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