Solubility of Gases in Liquids. 23: High-Precision Determination of Henry’s Law Constants of Propane Dissolved in Liquid Water from T = 278 K to T = 318 K

The solubility of propane (C₃H₈, component 2) in pure liquid water (H₂O, component 1) was determined at a total pressure of about 100 kPa from about T = 278 K to T = 318 K using an analytical method characterized by an imprecision of about ± 0.1% or less. The measurements were made with a Benson-Krause-type apparatus at roughly 5 K intervals. From the experimental results, Henry’s law constants h_{2 , 1}(T, P_σ,1) , also known as Henry fugacities, at the vapor pressure P_σ,1(T) of water, as well as the Ostwald coefficient L2,1∞(T,Pσ,1) at infinite dilution are rigorously obtained. The temperature dependence is accounted for by a three-constant Benson-Krause equation, i.e., by fitting ln [h_{2 , 1}(T, P_σ,1) / kPa] to a power series in 1/T. Subsequently, the partial molar enthalpy changes on solution ΔH2∞ of propane in water, and the partial molar heat capacity changes on solution ΔCP,2∞ , are reported (van ‘t Hoff analysis) and compared with calorimetrically determined quantities: agreement is highly satisfactory. We believe that our new values for the Henry fugacity and the Ostwald coefficient of propane dissolved in liquid water are the most reliable ones to date.