The static dielectric constant of liquid water between 274 and 418 K near the saturated vapor pressure

The complex dielectric constant (relative electric permittivity) epsilon(r) = epsilon' - i epsilon " of liquid water was redetermined in the temperatu re range 0 degrees C < t < 145 degrees C at pressures less than 440 kPa. In this work, epsilon(r) was deduced from measurements of the resonant freque ncies f(alpha) of a novel, re-entrant, two-mode, radio-frequency resonator. The frequencies ranged from 23 to 84 MHz and were well within the low-freq uency limit for epsilon' because (2 pi f(alpha)tau(max))(2) < 5 x 10(-5) wh ere tau(max) = 1.8 x 10(-11) s is the maximum relaxation time of water unde r the conditions studied. The data for epsilon' for two water samples diffe ring in conductivity by a factor of 3.6 and for the two resonant modes diff ering in frequency by a factor of 2.6 were simultaneously fit by the polyno mial function epsilon'(t) = 87.9144-0.404399t+9.58726 x 10(-4)t(2)-1.32802 x 10(-6)t(3) With a remarkably small residual standard deviation of 0.0055. The present data are consistent with previously published data; however, t hey are more precise and internally consistent. The present apparatus was a lso tested with cyclohexane and yielded the values epsilon'(t) = 2.0551 - 0 .00156t for 20 degrees C <1< 30 degrees C, in excellent agreement with prev iously published values.