The Static Dielectric Constant of Liquid Water between 274 K and 418 K near the Saturated Vapor Pressure

Jean Hamelin,1 James B. Mehl,1,2 and Michael R. Moldover1

The complex dielectric constant (relative electric permittivity) of liquid water was redetermined in the temperature range 274-418 K at pressures less that 440 kPa. In this work, the complex dielectric constant was deduced from measurements of the resonant frequencies of a novel, re-entrant, two-mode, radio-frequency resonator. The frequencies ranged from 23 MHz to 84 MHz and were well within the low-frequency limit for the static dielectric constant of water. The data for the static dielectric constant for two water samples differing in conductivity by a factor of 3.6 and for the two resonant modes differing in frequency by a factor of 2.6 were simultaneously fit by a third degree polynomial function with a remarkably small residual standard deviation of 0.0055. The present data are consistent with previously published data; however, they are more precise and internally consistent. The present apparatus was also tested with cyclohexane and yielded values in excellent agreement with previously published values.

1 Physical and Chemical Properties Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A.

2 Physics Department, University of Delaware, Newark, DE 19716