New considerations of the Barclay-Butler rule and the behavior of water dissolved in organic solvents.
The Barclay-Butler (B-B) rule, which states that a linear relationship exists between the standard deltaH(vap) and deltaS(vap) for simple, non-associated liquids and their solutions, has been used to distinguish associated ('abnormal') liquids from simple ('normal') liquids. The exact character of the B-B plots depends on the standard states chosen for the liquid/solution and vapor. We examine the effects of using number density for both vapor and liquid states for pure liquids, non-aqueous solutions, aqueous solutions and solutions in which water is the solute. The utility of B-B plots to detect solute-induced order is strengthened, and we also find remarkable changes in the modified B-B relationship: (1) the points for small, H-bonded liquids, including water, are pulled below the general B-B line; (2) many solutions containing small, simple solutes have negative entropies of vaporization; and (3) solutions of water in several organic solvents, relevant to studies of proteins and micelles, appear 'abnormal'.
Henn
Arthur R
AR
Department of Chemistry, Princeton University, Princeton, NJ 08544, USA. arhenn@marktek-inc.com
Kauzmann
Walter
W
D000465:Algorithms; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D009930:Organic Chemicals / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D009930:Organic Chemicals; D012996:Solutions; D012997:Solvents; D014867:Water