No abstract

No abstract

Densities, ρ, and compressibility coefficients, k = (v o − v)/v o, of ethylene glycol (1) + dimethylsulfoxide (2) mixtures were measured over the whole concentration range at pressures of (0.1 to 100) MPa and temperatures of (278.15 to 323.15) K. Excess molar volumes, isothermal compressibility, and thermal isobaric expansivity coefficients as well as thermal pressure coefficients were calculated. It was revealed that concentration dependences of specific volumes, v, at some state parameters passed a minimum. The shift of minimum position to molar fraction x 2 = 0.5 was observed with increasing pressure and decreasing temperature. The negative excess molar volumes, V m E, indicated a compression of EG (1) + DMSO (2) systems when mixing. Composition dependences of isothermal compressibility, κT, and thermal isobaric expansivity coefficients, α, as well as thermal pressure coefficients, β, were near-linear. Both increasing and decreasing of κT and β values were observed with x 2 increase depending on temperature and pressure magnitudes within the range of state parameters investigated.

No abstract

Densities of aqueous solutions of trimethylamine N-oxide (TMAO) were measured over the concentration range (0.0875 to 4.3251) mol·kg–1 at temperatures (278.15, 288.15, 298.15, 308.15, and 323.15) K and pressures (0.101, 10, 25, 50, 75, and 100) MPa. Volumetric properties such as apparent molar volume of TMAO, V ϕ,2, molar isothermal compression, K T,m, molar isobaric expansion, E P,m, and internal pressure, P int, of its aqueous solutions were calculated depending on concentration, temperature, and pressure. The volumetric partial properties of TMAO at infinite dilution in water (V 2 ∞, K T,2 ∞, and E P,2 ∞) were also determined. The results were discussed from the standpoint of solute–solute and solute–solvent interactions.