<i>PVT</i> Properties of Water. II. Virial Coefficients in the Range 150°–450°C without Independent Measurement of Vapor Volumes

Abstract

The equation of state of steam has been determined at 25° intervals from 150° to 450°C by measuring the mass of water injected into a high-temperature vessel as a function of pressure. The observations have been analyzed by a new method that does not require an independent volume of the vessel and are reported as the second and third virial coefficients and as empirical equations for them. The standard error of the second virial coefficient, taking account of the effects of experimental scatter and of truncation of the virial equation, which are comparable at 450°C, is 3% at 150° and 1% at 450°C. The Stockmayer potential fits the second virial coefficient fairly well, but predicts the wrong form for the third.