Solubility of xenon in liquid n-alkanes: Temperature dependence and thermodynamic functions

Measurements of the Ostwald solubility as a function of temperature L(T) are reported for 133Xe gas in liquid n-alkanes. All the alkanes from n-C5H12 through n-C20H42 were investigated and the temperatures ranged from 10.0 to 50.0 °C. The experimental method is recently developed and has some unique aspects. From the temperature dependent results the chemical potential Δμ20(T), the enthalpy ΔH̄20, and the entropy ΔS̄20 of solution were determined. Values for Δμ20(T) ranged from 2546 cal/mol for n-C7H16 at 50.0 °C to 1811 cal/mol for n-C14H30 at 10.0 °C. The range of ΔH̄20 was from −2818 cal/mol for n-C5H12 to −2117 cal/mol for n-C20H42, and the corresponding range in ΔS̄20 was −16.90 to −13.58 cal/mol K. A Barclay–Butler plot of the thermodynamic functions and a plot of the dependence of solubility on the Hildebrand solubility parameter for this system are displayed. All of the data obtained in this experiment may be given to better than 0.8% by the empirical relation Δμ20=−RT ln x2=−0.0637nT+2.575×10−2T2, in which x2 is the mole fraction of solute in the solvent at 1 atm partial pressure and T is the absolute temperature. Because the solute is an inert monatomic gas and the solvents are a single homologous series of nonpolar liquids, the results show some interesting simple physical interpretation.