From owner-biophysics@net.bio.net Sat Jan 03 22:00:00 1998 Path: biosci!agate!logbridge.uoregon.edu!europa.clark.net!206.229.87.25!news-peer.sprintlink.net!news.sprintlink.net!Sprint!worldnet.att.net!news.u.washington.edu!fujimoto From: fujimoto@u.washington.edu (Bryant Fujimoto) Newsgroups: bionet.biophysics Subject: Re: Reversibility of chemical reactions Date: 4 Jan 1998 06:11:04 GMT Organization: University of Washington Lines: 34 Distribution: bionet Message-ID: <68n95o$o3c$1@nntp3.u.washington.edu> References: <68l8r0$scl@mserv1.dl.ac.uk> NNTP-Posting-Host: homer03.u.washington.edu X-Trace: nntp3.u.washington.edu 883894264 24684 (None) 140.142.64.6 X-Complaints-To: help@cac.washington.edu NNTP-Posting-User: fujimoto Pentcho Valev writes: >2) If you >disagree, please explain how a chemical reaction can proceed reversibly so >that dS = dQ/T, the chemical work extracted is maximal etc. Pentcho I'm not sure if this will work, but it is usually possible to at least talk about changing the volume or temperature of a system reversibly. For a gas phase reaction, changing the volume will change the concentrations of reactants and products. Depending on the stoichiometry, this may shift the reaction one way or the other. Changing the temperature can change the equilibrium constant and in so doing shift the reaction. Before you run off and try to do something with this, you need to (1) figure out what it means for a process to be reversible, (2) verify that my suggestions or any other ideas you may have can be carried out reversibly, and (3) you need to pick a reaction (no more A+B->C+D, the exact properties of the reactants and products are important). One final thing, before I will be willing to do anything more than take a cursory look at what you come up with, you need to explain why this is necessary. That is, what is wrong with using the other predictions to test thermodynamics? Why do you believe it is possible that the entropy not be a state function, and yet all the other predictions still be satisfied? Quite simply, I think thermodynamics has been tested quite thoroughly. So, before I spend much time trying to figure out whether any new test has anything to say about the validity of thermodynamics, I want an explanation about why the tests that have already been done are inadequate. Regards, Bryant .