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"Icebergs" or no "Icebergs" in aqueous alcohols?: Composition-dependent mixing schemes

Title"Icebergs" or no "Icebergs" in aqueous alcohols?: Composition-dependent mixing schemes
Publication TypeJournal Article
Year of Publication2004
AuthorsKoga, Y, Nishikawa, K, Westh, P
JournalJournal of Physical Chemistry A
Volume108
Pagination3873-3877
Date PublishedApr
Type of ArticleArticle
ISBN Number1089-5639
Keywords2-BUTOXYETHANOL, BUTANOL, fluctuations, hydration, HYDROPHOBIC SURFACES, MIXTURES, PARTIAL MOLAR VOLUMES, TERT-BUTYL ALCOHOL, WATER-RICH REGION, X-RAY-SCATTERING
Abstract

The classical concept of "iceberg formation" is modified by our recent thermodynamic studies. The local enhancement of the hydrogen-bond network of H2O in the immediate vicinity of small nonelectrolyte solutes (i.e., the "iceberg formation") is still correct. However, the hydrogen-bond probability of bulk H2O away from solutes is reduced progressively, as the solute composition increases. When the hydrogen-bond probability of bulk H2O is reduced to the bond percolation threshold of the hexagonal ice connectivity, the hydrogen-bond percolation is lost and a qualitatively different mixing scheme sets in, whereby the solution consists of two kinds of clusters. In the solute-rich region, solute molecules form Clusters of its own kind. Thus, the "iceberg, formation" is basically correct within a narrow range in the H2O-rich region for small nonelectrolyte solutes. Thus, reference made to the "iceberg" concept in recent literatures should be clarified in terms of the concentration range and the size of solute in question.

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