The density of ordinary water from 0°to 150°C. is well represented by a rational function with seven parameters. Similar functions, with fewer parameters, are given for DzO, H2O18, D2O18, and T2O. The density, specific volume, thermal expansivity, and compressibility of ordinary water are given at intervals of 2°from -20°to -10°C. and at intervals of 1°from -10°to +110°C. The density of 02O is given at 5°intervals from 0°to 101°C.The DENSITY of liquid water from 80°to 150°C. was redetermined by Kell and Whalley (10) in connection with measurements of the compressibility of water from 0°to 150°C. These densities, plus others ( 14) not yet incorporated in tables, make possible a table of greater range ( 22), or reliability (20), than those now available, provided a suitable interpolating function can be found.A function, chosen for goodness of fit to the most reliable densities of ordinary water, has been used to give a table. The same type of function also has been found satisfactory for water of other isotopic composition.ORDINARY WATER Data Used. Tilton and Taylor ( 22) analyzed Chappuis's (2) experimental densities for 0°to 42°C. Improvement in that temperature range must wait for further precise experimental data. To avoid reanalyzing the great number
The change of density of liquid water under pressure has been calculated from the speed of sound u by fitting u−2 as a polynomial in temperature and pressure, integrating with respect to pressure, and allowing for the difference between isothermal and adiabatic compressions. By comparing calculations done by different methods on the same data and on different data it appears that the densities so obtained are accurate to about 20 ppm at 1 kbar. These densities are about 100 ppm greater than the densities obtained by us some years ago by direct measurement of the compressions in the range 0–150 °C and 0–1 kbar relative to a stainless steel vessel. It seems likely that the compressibility of the vessel used in this work is too high by about 0.1 Mbar−1. A correction to the compressibility of the vessel is proposed to bring the densities in the range 0–100 °C and 0–1 kbar into agreement with the values from the speed of sound. The same correction should apply in the range 100–150 °C, and the corrected values appear to be the best available. A hysteresis between the runs at increasing and decreasing pressures is now ascribed to a hysteresis in the position of some nylon washers. The two types of runs have therefore now been analyzed independently, and revised densities are tabulated.
A review is made of measurements of the effect of temperature, pressure, isotopic composition, and dissolved atmospheric gases on the density of liquid water at temperatures to 100 <,~/C. The molar volume is expanded as a multiple power series in the variables, and the coefficientEi determined. A number of gaps become evident in our knowledge of properties that are within the capacity of current measurements. For example, there appears to be no measurement of the effect of oxygen isotopes on the compressibility. Data o~ the thermal expansion of D20 are strikingly inconsistent. The partial molar volumes of dissolved gases are only sketchily known. At O, __ 6)(~'~ equilibration with the oxygen, nitrogen, and argon of the atmosphere lowers the density about 3 p.p.m., while atmospheric carbon dioxide raises it about 0.3 p.p.m. Appendix I discusses the care needed to obtain various degrees of precision in practical density measurements, and the effect of isotopic uncertainties on them. Appendix II treats the representation of the equation of ' state of water at slightly higher pressures~
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