To the issue of temperature-dependent behavior of standard molar volumes of components in the binary system (water + tetrahydrofuran) at ambient pressure

• Densities of aqueous THF at nine temperatures from (278.15 to 318.15) K were measured.
• Temperature-dependent standard molar volumes of THF in water were calculated.
• The analysis of excess standard molar volumes in the (water + THF) system was made.
• The use of Redlich–Kister equation to obtain standard molar volumes is discussed.

This report presents a comparative analysis of temperature-dependent data on density of both dilute aqueous solutions of tetrahydrofuran (THF) and dilute solutions of water in THF, as well as standard molar volumes of water or THF as a solute. For this purpose, new results on studying the volume-related properties of THF in a water-rich region at temperatures from (278.15 to 318.15) K, with a step of 5 K, and at the ambient pressure have been derived densimetrically. In discussion, some comments on previously published investigations, being related to temperature-dependent changes in the solution density and standard molar volumes of components of the system (water + THF), have been made.

The standard molar volume of tetrahydrofuran (THF) in water, VTHF∘(■), is a close-to-linear function of temperature and becomes increasingly appreciable with rising of the latter. Herewith the molar volume of pure THF, VTHF (□), is retained to be larger, as compared to VTHF∘, over all the temperature range studied.Figure optionsDownload as PowerPoint slide