Microwave Absorption and Molecular Structure in Liquids. LXVI. The Dielectric Relaxation of the Water—Dioxane System and the Structure of Water

Abstract

The dielectric constants and losses of a series of mixtures of water and dioxane (0.2–0.8 mole fraction) have been measured at wavelengths of 0.217, 1.223, 3.193, and 10.09 cm, and 575 m and temperatures of 1°,10°,25°,40°, and 55°C. The results show that the mixtures have two dielectric relaxation times in contrast to the single time found for water. The results are interpreted as indicating a very rapidly fluctuating structure for pure water in which the molecules are constantly forming, breaking, and reforming hydrogen bonds to their neighbors. At any given instant there are unbonded molecules, as well as singly, doubly, triply, and quadruply bonded molecules, and molecules in all intermediate stages of bonding. However, the fluctuations of structure are so rapid that, averaged over the extremely short time required for dielectric relaxation, the molecules and their immediate environments are approximately the same. In the water—dioxane mixtures, the dioxane molecules alter the environments of some of the water molecules and thereby introduce a second relaxation time.