Gas-liquid chromatographic method for determination of partial molar free energy at infinite dilution in volatile solvent and its application to acetonitrile/benzene systems

Gas-liquid chromatographic determination of partial molar free energies at infinite dilution of 18 organic solutes in n-hexane solvent at 25.0.degree.

“…The values of -dW/df corresponding to -dtR/di listed in Table I are in the region of 0.014-0.095 gh"1. Most of these -d W/dt are greater than those for acetonitrile and benzene solvents at 20 °C (1). The scattering behavior of -dW/dt for runs of the present system is, however, similar to those found for the acetonitrile/benzene systems.…”

“…The scattering behavior of -dW/dt for runs of the present system is, however, similar to those found for the acetonitrile/benzene systems. The values of-(dW/ dt)vap, calculated by eq 12 in the previous work (1), are in the region of 0.09-0.13 g h"1. Thus, the delivery of the solvent into the column as saturated vapor accompanies the mist and/or liquid also in the present case of n-hexane solvent at 25 °C.…”

“…The solute sample was a gaseous mixture of the solute vapor and hydrogen gas, in which the solute partial pressure was about half of its saturated vapor pressure. The apparatus and the details of the experimental procedure for n-pentane and propane solutes were essentially the same as those for the acetonitrile/benzene systems at 20 °C described previously (1). The experimental conditions in this work were kept constant throughout the measurements with n-hexane as the solvent and a temperature of 25.0 °C.…”

“…With the VgT value obtained for each solute, the G°°was evaluated as the sum of the free energy of solution at infinite dilution and the free energy of imperfection in the vapor phase (1). (3) All the symbols used in the equations as well as in the text are the same as defined in the previous paper (1).…”

Measurement of limiting activity coefficients using non-steady-state gas chromatography

“…Conventional gas-liquid chromatography (GC) has often been used to measure the infinite dilution values of volatile solutes in a stationary phase (Conder and Young, 1979), but the low volatility of the solvent restricts application to systems primarily of theoretical interest. Volatile solvents have been studied by GC by presaturating the carrier gas with solvent vapors (Mash and Pemberton, 1980;Eckert et al, 1981;Thomas et al, 1982;Thomas and Eckert, 1984;Palmer, 1984; Terasawa et al, 1986;Itsuki et al, 1987). However, the weight of solvent phase present in the column is never known accurately; either the column has to be removed and weighed after a series of measurements, or the solvent weight has to be calculated based on the retention volume of a solute of independently known activity coefficient.…”