Activity of Water, Osmotic and Activity Coefficients of Sodium Glutamate and Sodium Aspartate in Aqueous Solutions at 310.15 K
Elena N. Tsurko,1,* Roland Neueder2 and Werner Kunz2
1 Scientific-Research Institute of Chemistry, Karasin
National University, Svoboda Sq.4, 61077 Kharkiv, Ukraine
2 Institute of Physical and Theoretical Chemistry,
University of Regensburg, D-93040 Regensburg, Germany
* Corresponding author: E-mail:
Jelena.N.Tsurko@univer.kharkov.ua
Abstract
The vapour pressures of aqueous solutions of sodium L-glutamate (mi
= 0.05–0.57 mol kg–1) and sodium L-aspartate (mi
= 0.005–0.48 mol kg–1) were precisely measured at T = 310.15 K and
the activity of water and the osmotic and activity coefficients of the solutes
were calculated from these data. The concentration dependence of the osmotic
coefficients is described with the help of the Pitzer equation and the mean
spherical approximation (MSA). It is shown that it is possible to describe
thermodynamic properties of sodium aspartate and sodium glutamate solutions up
to 0.5 molkg–1 with distance parameter R as the single fit
parameter.
Keywords: Vapor pressure osmometry, osmotic coefficients, sodium L-glutamate, sodium L-aspartate, short-range interactions, electrostatic interactions