Journal of Physical Chemistry A, Vol.106, No.33, 7557-7561, 2002
Pressure effect on the density of water
A simple two-state structural model has been shown capable of quantitatively unifying oxygen-related properties of liquid water. The key variables, which remain invariant among all properties studied, are the pressure-/temperature-dependent densities and fractional compositions of the two contributing structures. In this paper, the pressure dependence of these variables for different temperatures is evaluated from density measurements of water for pressures up to 8 kbar. Data derived earlier from isothermal compressibilities provided only the leading term in the steep pressure dependence of these quantities. This leading term is found here to provide a good. representation of the density of water in the pressure range from I to 1026 bar for 0 less than or equal to t less than or equal to 40 degreesC. A correctly curved pressure dependence is introduced for the accurate description of pressure-dependent properties such as the refractive index of water and the pressure denaturation of proteins, where the experimental pressure range usually exceeds I kbar.