Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84 exptools; site ihuxn.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!ihuxn!jho From: jho@ihuxn.UUCP (Yosi Hoshen) Newsgroups: net.origins Subject: Re: On Natural Selection Message-ID: <1046@ihuxn.UUCP> Date: Sun, 5-May-85 09:47:47 EDT Article-I.D.: ihuxn.1046 Posted: Sun May 5 09:47:47 1985 Date-Received: Mon, 6-May-85 01:49:29 EDT References: <1485@hao.UUCP> <213@phri.UUCP> <298@scgvaxd.UUCP> <1037@ihuxn.UUCP> <302@scgvaxd.UUCP> Distribution: net Organization: AT&T Bell Laboratories Lines: 31 Responding to my previous posting Dan Boskovich asks: > Why do you say that ice is more ordered than liquid water? Ice has a crystal structure. In a crystal the basic structural unit, containing few molecules (usually 1, 2, 3, .), is repeated throughout the crystal, over 10**23 or more molecules. In liquids, e.g. water, such order does not exist. There may be some local order over 10 or 20 molecules. However that order does not extends itself over the macroscopic sample. It is possible to measure the decrease in entropy, which is related to the increase in order, for liquid to solid transition. When liquid water converts to solid water (ice) there is a discontinuity in the entropy function upon freezing. The change in entropy for freezing is -L/T where L is the latent heat of melting and T is the temperature of melting (T is given in the absolute temperature units). For water(L) to water(S) transition we get -333/273 = -1.2 joules/(gram degree) for the the entropy drop at 0 degrees C. For a better understanding of the second law of thermodynamics, entropy, order etc., I suggest reading K. Denbigh's book: "The principles of chemical equilibrium" published by Cambridge University Press. -- Yosi Hoshen, AT&T-IS Naperville, Illinois, (312)-979-7321, Mail: ihnp4!ihuxn!jho