4 research outputs found
Densities and Volumetric Properties of Aqueous Solutions of {Water (1) + <i>N</i>‑Methylurea (2)} Mixtures at Temperatures of 274.15–333.15 K and at Pressures up to 100 MPa
Densities
of the mixture {water (1) + <i>N</i>- methylurea
(2)} in the concentration range to mole fraction <i>x</i><sub>2</sub> = 0.07071 (or to the solution molality concentration <i>m</i><sub>2</sub> = 4.22335 mol·kg<sup>–1</sup>)
at atmospheric pressure in the temperature range from 274.15 to 333.15
K and compression <i>k</i> = Δ<i>V</i>/<i>V</i><sub>0</sub> at pressures to 100 MPa (10, 25, 50, 75, and
100) in the temperature range from 278.15 to 323.15 K (278.15, 288.15,
288.15, 308.15, 323.15) in the same concentration range were calculated
in this study. The apparent molar volumes of <i>N</i>-methylurea <i>V</i><sub>ϕ,2</sub> and the partial molar volumes of both
components <i>V̅</i><sub>1</sub> and <i>V̅</i><sub>2</sub> in the mixture, molar isothermal compressibilities <i>K</i><sub><i>T,m</i></sub>, molar isobaric thermal
expansions <i>E</i><sub><i>P,m</i></sub>, and
isochoric coefficients of thermal pressure β of the mixture
were calculated. Moreover, volumetric measures for the infinitely
dilute solution of <i>N</i>-methylurea solution were calculated:
limiting partial molar volumes <i>V̅</i><sub>2</sub><sup>∞</sup>, the limiting
partial molar isothermal compressibilities <i>K̅</i><sub><i>T</i>,2</sub><sup>∞</sup>, and the limiting partial molar isobaric thermal expansions <i>E̅</i><sub><i>P</i>,2</sub><sup>∞</sup>. The results obtained are discussed
from the point of view of solute–solvent and solute–solute
interactions
Densities and Molar Isobaric Thermal Expansions of the Water + Formamide Mixture over the Temperature Range from 274.15 to 333.15 K at Atmospheric Pressure
The
density of the {water (1) + formamide (2)} mixture has been
measured over the whole composition range at temperatures from 274.15
to 333.15 K at atmospheric pressure using the vibration densimeter.
The volumetric parameters of the mixture, such as the excess molar
volume, molar isobaric thermal expansions, and apparent and partial
molar volumes of water and formamide, as well as their limiting values,
have been calculated. It was shown that the mixture formation resulted
in the volume decrease at all temperatures, and the largest absolute
value of the excess molar volume corresponded to the mixture composition
of 2H<sub>2</sub>O-FA. The limiting partial molar volumes of water
and formamide increased with the temperature rise. At a temperature
of about 323 K the limiting partial molar volume of water became larger
than its own molar volume
Density and Volumetric Properties of Aqueous Solutions of Trimethylamine <i>N</i>‑Oxide in the Temperature Range from (278.15 to 323.15) K and at Pressures up to 100 MPa
Densities of aqueous solutions of
trimethylamine <i>N</i>-oxide (TMAO) were measured over
the concentration range (0.0875
to 4.3251) mol·kg<sup>–1</sup> 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, <i>V</i><sub>ϕ,2</sub>, molar isothermal
compression, <i>K</i><sub><i>T</i>,m</sub>, molar
isobaric expansion, <i>E</i><sub><i>P</i>,m</sub>, and internal pressure, <i>P</i><sub>int</sub>, of its
aqueous solutions were calculated depending on concentration, temperature,
and pressure. The volumetric partial properties of TMAO at infinite
dilution in water (<i>V</i><sub>2</sub><sup>∞</sup>, <i>K</i><sub><i>T</i>,2</sub><sup>∞</sup>, and <i>E</i><sub><i>P</i>,2</sub><sup>∞</sup>) were also determined. The results
were discussed from the standpoint of solute–solute and solute–solvent
interactions