Physical Chemistry of Aqueous Systems: Meeting the Needs of Industry

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

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

THE ENTROPY OF GLASSY WATER

DOI: 10.1615/ICPWS-1994.450
pages 347-354

Abstract

Glassy solid forms of water can be made by vapor deposition, by the rapid cooling of small liquid droplets or by squashing ice. For the glass to be connected to normal water by a reversible path at atmospheric pressure its residual excess entropy relative to ice needs to be effectively zero. Measurement of the rates of evaporation of glassy water and ice near 150 K gives a measure of their free energy difference which implies an entropy difference of ΔS = 1.3±1.7 J/(K·mol) at 150 K. There are two interpretations of the small value of ΔS, depending on whether the measured free energy of the glass reflects the calorimetric or the statistical mechanical value of the entropy of a glass. An experiment is proposed to test that issue.