Apparent Molar Volumes and Isentropic Compressibilities of Tetraalkylammonium Bromides in Aqueous Propane-1,2-diol. An Attempt to Design Hydraulic Liquids

Abstract

Apparent molar volumes and apparent molar compressibilities for tetramethylammonium, tetraethylammonium, tetrapropylammonium, and tetrabutyl-ammonium bromides in water, propane-1,2-diol, and water–propane-1,2-diol mixtures (mass fraction: 0.25, 0.50, and 0.75) have been determined from solution density measurements at T = 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15 K and sound velocity measurements at T = 298.15 K as a function of the concentration of tetraalkylammonium salt. The limiting apparent molar volumes and limiting apparent molar compressibilities have been derived using the Masson equation. The limiting expansion coefficients for tetraalkylammonium bromides in the studied solutions were also estimated. These parameters have been discussed in terms of structural factors controlling the properties of the systems.