A Thermodynamic Model on a Linear Rule between the Molal Concentration Exponential and the Osmotic Coefficients on Mole Fraction Base in Electrolyte Solutions and its Application
Pages 194-212
Zheng Fang

DOI: http://dx.doi.org/10.6000/1929-5030.2015.04.04.5

Published: 17 December 2015

Abstract: A linear rule is discovered. That is the osmotic coefficients on mole fraction base (ω) are linearly related to the molal concentration exponential (m^k₂) in single electrolyte solutions. Based on this rule, a thermodynamic model is developed and successfully used to the single electrolytes with various valent types, such as uniunivalent, biunivalent, triunivalent, tetraunivalent,bibivalent, andtribivalent to predict their conventional osmotic coefficients on molal base (Φ), and also other properties, such as the relative molal vapor pressure lowering, the equivalent conductivity. Besides m^k₂, the x^k₂ (the concentration exponential of mole fraction of solute) m^k₂ln(m^k₂), and x^k₂ln(x^k₂) are also linearly related to ω, respectively. They are all capable to be used to reproduce some properties of single electrolyte solutions. The examples with satisfied results have been given.

A Thermodynamic Model on a Linear Rule between the Molal Concentration Exponential and the Osmotic Coefficients on Mole Fraction Base in Electrolyte Solutions and its Application
Pages 194-212
Zheng Fang

DOI: http://dx.doi.org/10.6000/1929-5030.2015.04.04.5

Published: 17 December 2015

Abstract: A linear rule is discovered. That is the osmotic coefficients on mole fraction base (ω) are linearly related to the molal concentration exponential (m^k₂) in single electrolyte solutions. Based on this rule, a thermodynamic model is developed and successfully used to the single electrolytes with various valent types, such as uniunivalent, biunivalent, triunivalent, tetraunivalent,bibivalent, andtribivalent to predict their conventional osmotic coefficients on molal base (Φ), and also other properties, such as the relative molal vapor pressure lowering, the equivalent conductivity. Besides m^k₂, the x^k₂ (the concentration exponential of mole fraction of solute) m^k₂ln(m^k₂), and x^k₂ln(x^k₂) are also linearly related to ω, respectively. They are all capable to be used to reproduce some properties of single electrolyte solutions. The examples with satisfied results have been given.

Structural Data, Linear and Nonlinear Optical Properties of Some Cyclic Phosphazenes: A Theoretical Investigation
Pages 132-142
D. Hadji and A. Rahmouni

DOI: http://dx.doi.org/10.6000/1929-5030.2015.04.03.1

Published: 08 September 2015

Abstract: We report ab initio and DFT calculation of structural data, dipole moment, diagonal vibrational and electronic contributions to polarizability, vibrational and electronic contributions to first hyperpolarizability of some cyclic phosphazenes. The electronic structure of substituted cyclic phosphazenes has been investigated using Hartree-Fock and density functional theory. The vibrational and electronic contributions to polarizabilities and first hyperpolarizability of these molecules were calculated with HF method, and different DFT levels used the traditional B3LYP and PBE functional and the long-range corrected functional like Coulomb-attenuating method CAM-B3LYP, LC-BLYP and wB97XD used different basis sets. These cyclic phosphazenes adopts a planar structure. The study reveals that the cyclic phosphazenes derivatives have large vibrational contribution to static first hyperpolarizability values. The results obtained from this work will provide into the electronic properties of this important class of inorganic polymers.

Keywords: Mean polarizability, polarizability anisotropy, vibrational and electronic polarizability, vibrational and electronic first hyperpolarizability.

Thermodynamic Modeling of Chiral Compounds Solubility Using Correlative and Predictive Models
Pages 143-151
Morteza Salimi, Bahman Zarenezhad, Hossein Fakhraian and Ebrahim Choobdari

DOI: http://dx.doi.org/10.6000/1929-5030.2015.04.03.2

Published: 08 September 2015

Abstract: Many intermolecular forces and parameters affect the solubility of a compound in a solvent. Various thermodynamic models are presented to predict these parameters and determine solid liquid equilibrium data. By selecting suitable thermodynamic model for solubility modeling, calculation error is reduced and the results will be closer to the experimental data. Herein, the ability of two predictive and two correlative models in solubility modeling of chiral compounds is investigated. Thus, solubility of pure and racemic forms of chiral Ketamine, Mandelic acid and 3-Chloromandelic acid is evaluated using UNIQUAC and NRTL models. The solubility modeling of pure and racemic forms of Ketamine in Ethanol is also determined by UNIFAC and NRTL-SAC models. There are good agreement between experimental data and results of NRTL and UNIQUAC models. Predictive NRTL-SAC model shows smaller deviation than UNIFAC in solubility determination of pure and racemic form of Ketamine.

Keywords: Solubility, Chiral compounds, Thermodynamic modeling, NRTL-SAC, UNIFAC, UNIQUAC, NRTL..

Free Unsolvated Formaldehyde in Solutions: Influence of Temperature, Solvent Permittiity, and Total Formaldehyde Concentration
Pages 152-159
Michael M. Silaev

DOI: http://dx.doi.org/10.6000/1929-5030.2015.04.03.3

Published: 08 September 2015

Abstract: A mechanism of the initiated nonbranched-chain process of forming 1,2-alkanediols and carbonyl compounds in alcohol–formaldehyde systems is suggested. The quasi-steady-state treatment is used to obtain kinetic equations that can describe the nonmonotonic (with a maximum) dependences of the formation rates of the products on the concentration of free unsolvated formaldehyde. The experimental concentration of the free unsolvated form of formaldehyde are given at the different temperatures, solvent permittivity and total concentrations of formaldehyde in water and alcohols. An empirical equation for calculating the free formaldehyde concentration in alcohol–formaldehyde (including water/ethanediol–formaldehyde) systems at various temperatures and total formaldehyde concentrations and an equation for evaluating solvent concentrations in these systems were derived.

Keywords: Free formaldehyde, 1-hydroxyalkyl radical, formyl radical, equation.