I. Enthalpy change upon vaporization of the hydrocarbons n-pentane, cyclohexane and 1-butene. II. Evaluations of diffusion coefficients for the methane-n-butane system based on gradients in thermodynamic state properties

Abstract

I. An experimental investigation was made of the enthalpy change upon vaporization of three hydrocarbons in the pure state. The hydrocarbons studied were n-pentane, cyclohexane and 1-butene. Direct calorimetric determinations of the enthalpy change were carried out at 30° temperature intervals in the temperature range 100°F. up to 310°F. and at pressures in the range 3-250 lb. per sq. in. abs. The experimental data was smoothed and interpolated utilizing residual techniques. Critically chosen values of the enthalpy change upon vaporization of n-pentane, cyclohexane and 1-butene are presented at even temperature increments of 10°F. The data extrapolated to 77°F. is in excellent agreement with selected values at 77°F. reported by Rossini which were measured at the National Bureau of Standards. II. Evaluations were made of the phenomenological coefficient and the diffusion coefficients based on gradients in the chemical potential and fugacity for methane diffusing in the liquid phase of the methanen-butane system. Values of these coefficients are presented at six pressures evenly spaced in the pressure range 250-1500 lb. per sq. in. at each of the temperatures 100°, 160° and 220°F. The evaluated coefficients are marked functions of the state of the phase.