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-sigma,P-1), also known as Henry fugacities, at the vapor pressure P-sigma,P-1(T) of water, as well as the Ostwald coefficient (L2,1T)-T-infinity(, P-sigma,P-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-sigma,P-1)/kPa] to a power series in 1/T. Subsequently, the partial molar enthalpy changes on solution Delta H-2(infinity) of propane in water, and the partial molar heat capacity changes on solution Delta C-P,2(infinity), 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.