Conductivity and resistivity of water from the melting to critical points

An accurate knowledge of the theoretical conductivity and resistivity of water over a wide range of temperatures is necessary to facilitate the analysis for trace ionic impurities in water. In this paper, values for pH, conductivity, resistivity, and temperature coefficient of pure water over the range of 0-374/sup 0/C are determined by utilizing sources of fundamental data of better accuracy than those previously available. These calculations are based on improved values for the equivalent ionic conductances of hydrogen and hydroxyl ions, the ionization constant of water, and the density of water. The extent of improvement over earlier values is noted and comparison is made with experimental measurements. New values of the ionization constant, conductivity, and resistivity of water at the critical temperature, 374/sup 0/C, are given. The use of low-temperature resistivity measurements to increase the sensitivity for detection of ionic impurities to the fractional-parts-per billion level is discussed.

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