Solubility of gases in liquids. 18. High-precision determination of Henry fugacities for argon in liquid water at 2 to 40�C

Abstract

The solubility of argon in pure liquid water was measured at ca. 100 kPa and from 2 to 40°C using an analytical method characterized by an imprecision of about ±0.05%. From the experimental results, Henry fugacities H 2,1 (T,P s,1 ) (also known as Henry's Law constants or Henry coefficients) at the vapor pressure P s,1 of water as well as Ostwald coefficients L 2,1 ∞ at infinite dilution were obtained. Measurements were made at roughly 0.5°C and/or 1° intervals between 2 and 8°C (region I), and at 5°C intervals above 10°C (region II). A difference plot ΔlnH 2,1 /ΔT suggests an unusual temperature dependence in region I, i.e., between 2 and 8°C. Because of this, the data were treated separately in two parts corresponding to these two regions. Our results are compared with the recent high-precision data of Krause and Benson (Henry fugacities), and with calorimetrically determined quantities (enthalpies and heat capacities of solution). Finally, experimental results are compared with values calculated via scaled particle theory.