Abstract
Experimental pressureโvolumeโtemperature data available in the literature for argon have been utilized to produce relationships for the prediction of densities for reduced temperatures up to T~R~ = 3.38 and reduced pressures up to P~R~ = 50. A plot of reduced pressure vs. reduced temperature for constant reduced density was made for argon, in which each isochor terminates at the vaporโpressure curve. This information was utilized to develop a third degree polynomial relationship between the normalized pressure and the normalized temperature for each isochor by the method of least squares. This method was also used to establish the dependence of the coefficients of the polynomials on reduced density.
The resulting relationships permitted the calculation of desities for argon from the critical constants, vapor pressure function, and the saturated vapor and liquid densities of the substance with a trialโandโerror procedure. For fiftyโseven densities for the dense gaseous and liquid phases of argon an average deviation of 1.29% with a maximum value of 3.66% resulted between calculated and reported values. The relationships developed in theis study have also been found to be applicable to nitrogen, oxygen, carbon monoxide, and methane, whose critical compressibility factors are similar to that of argon.