Experimental Study of the Equation of State of Liquid Krypton

Abstract

The gas expansion method has been used to measure the density of liquid krypton at 11 temperatures from 120 to 220°K and at pressures up to 3680 atm. The results have been fitted to the Strobridge equation, which has been used to estimate, at regular intervals of pressure and temperature, the following properties: density, isothermal compressibility, thermal expansion coefficient, thermal pressure coefficient, configurational internal energy, and entropy relative to the saturated liquid. The equation of state results, together with estimated values of the third virial coefficient and published values of vapor pressure, second virial coefficient, and sound velocity in the liquid phase, have been used to estimate the following properties of the saturated liquid: enthalpy of vaporization, configurational internal energy, isothermal compressibility, thermal expansion coefficient, thermal pressure coefficient, adiabatic compressibility, and specific heats. The linear dependence of configurational internal energy on density, over a wide range of pressures and temperatures, suggests a relatively simple form for a hard sphere equation of state for monatomic liquids. The evaluation of constants for such an equation is briefly discussed.