Phenomenon of “negative partial molar expansibility” of water in tetrahydrofuran: How plausible is it?: Discussion on the paper “Volumetric properties on the (tetrahydrofuran + water) and (tetra-n-butylammonium bromide + water) systems: Experimental measu

In order to answer the question: is a solute water “negatively expansible” in tetrahydrofuran or not (?), a comparative analysis of own and literature data on the temperature-dependent partial volumes at the infinite dilution of water isotopologues in tetrahydrofuran have been carried out. Used for computing the limiting partial (apparent) volumes of water isotopologues, densities of H2O and D2O solutions in the solvent studied, with the solute mole fractions ranging up to ∼0.043, were measured with an error of 1.5 · 10−5 cm3 · mol−1 at (278.15, 288.15, 298.15, 308.15, and 318.15) K and atmospheric pressure using a vibrating tube densimeter. It has been shown that the partial molar volume of H2O or D2O at infinite dilution increases with rising temperature; that is, the isotopically distinguishable solutions of water in tetrahydrofuran do not have the unusual structure-packing behavior being characteristic of the water-containing system with the so-called phenomenon of “negative partial molar expansibility”.