Physical Chemistry of Aqueous Systems: Meeting the Needs of Industry

ISBN Print: 978-1-56700-034-4

ISBN Online: 978-1-56700-445-8

CLATHRATE STRUCTURES AND THE ANOMALIES OF SUPERCOOLED WATER

DOI: 10.1615/ICPWS-1994.400
pages 308-316

Resumo

Many small hydrophobic molecules or molecules with a hydrophobic group form stoichiometric clathrate compounds with water at low temperature. The water in these compounds forms a relatively strain free, hydrogen bonded cage in which resides the hydro­phobic entity. It is significant that dilute aqueous solutions of such molecules often show nonideal behavior such as enhanced temperatures of maximum density and specific heats, and binary liquid phase stability. Furthermore it has been shown that the anomalous properties of supercooled water can be enhanced by the addition of small hydrophobic entities. Recent SAXS data on extremely supercooled water showed the correlation length to be nondivergent, which is inconsistent with a critical phenomena type description of water's supercooled anomalies, but can fit with a picture wherein clathrate-like structures are forming. In this paper I will present a broad ensemble of evidence to support the contention that clathrate-like structures of hydrogen bonded water molecules form in liquid water, more so as it is cooled, and that these structures are responsible for the apparent anomalous behavior of supercooled water.