scholarly journals Vapour-liquid phase equilibria and thermodynamic properties of solutions of the ethylbenzene and n-alkylbenzenes binary systems

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Yuri K. Suntsov ◽  
Nina S. Suntsova
Keyword(s):  
Liquid Phase ◽  
Thermodynamic Properties ◽  
Vapour Pressure ◽  
Homologous Series ◽  
Binary Systems ◽  
Molar Mass ◽  
Helmholtz Energy ◽  
Binary Solutions ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour

The methods of theoretical description of the patterns of changes in thermodynamic properties depending on the composition and structure of solution components are a priority direction in the development of the theory of solutions. This article is devoted to the establishment of relationships between the thermodynamic properties, composition of solutions, and the structure of their components. The study of the thermodynamic properties of binary solutions formed by a common solvent (ethylbenzene) and substances of the homologous series of n-alkylbenzenes contributes to the establishment of the aforementioned relationships. In the production of ethylbenzene and its homologues, solutions based on n-alkylbenzenes are quite common. Alkylbenzenes are widely used in various fields of science and chemical technology as solvents, extractants, and plasticisers. Using the ebuliometric method, we measured the boiling points of solutions of four binary systems formed by ethylbenzene and n-alkylbenzenes under various pressure values. Compositions of equilibrium vapour phases of the binary systems were calculated using the obtained isotherms of saturated vapour pressure of the solutions. Using the Runge-Kutta method, the composition of the vapour phases of the solutions of the systems was calculated by the numerical integration of the Duhem–Margules equation on a computer. The obtained data on the vapour-liquid equilibrium became the basis for calculating the thermodynamic functions of the systems’ solutions. The Gibbs and Helmholtz energy values, the enthalpies of vaporisation and mixing, the internal energy, and entropy of solutions were calculated. The thermodynamic properties of the solutions were calculated using a comparison of the values baed on two standards: an ideal solution and an ideal gas. It was found that the values of the Helmholtz energy linearly depend on the molar mass of the substance (the number of –CH2– groups in a molecule) in the homologous series of n-alkylbenzenes. An increase in the Helmholtz energy values for n-alkylbenzenes in the homologous series is associated with a linear increase in the molar volume of liquid substances and an exponential decrease in the saturated vapour pressure of substances. For binary solutions of constant molar concentrations formed by ethylbenzene and n-alkylbenzenes, the Helmholtz energy linearly depends on the molar mass (number of –CH2– groups in the molecule) of n-alkylbenzene in the homologous series. We obtained an equation that makes it possible to predict the thermodynamic properties of solutions of binary systems with high accuracy. The equation accelerates the process of studying vapour-liquid phase equilibria and thermodynamic properties of solutions of binary systems by 300 times. The determined patterns confirm the hypothesis of the additive contribution of functional groups to the thermodynamic properties of solutions. This hypothesis underlies the statistical theory of group models of solutions. The thermodynamic patterns determined by this study can also be used to solve a wide range of technological issues in the chemical industry.

scholarly journals Raoult’s law revisited: accurately predicting equilibrium relative humidity points for humidity control experiments

2016 ◽  
Author(s):  
Michael G. Bowler ◽  
David R. Bowler ◽  
Matthew W. Bowler
Keyword(s):  
Relative Humidity ◽  
Vapour Pressure ◽  
Control Device ◽  
Raoult’S Law ◽  
Simple Argument ◽  
Humidity Control ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour ◽  
Equilibrium Relative Humidity ◽  
Raoult's Law

AbstractThe humidity surrounding a sample is an important variable in scientific experiments. Biological samples in particular require not just a humid atmosphere but often a relative humidity (RH) that is in equilibrium with a stabilizing solution required to maintain the sample in the same state during measurements. The controlled dehydration of macromolecular crystals can lead to significant increases in crystal order, which often leads to higher diffraction quality. Devices that can accurately control the humidity surrounding crystals on a beamline have led to this technique being increasingly adopted, as experiments become easier and more reproducible. Matching the relative humidity to the mother liquor is the first step to allow the stable mounting of a crystal. In previous work, we measured the equilibrium relative humidity for a range of concentrations of the most commonly used precipitants and showed how this related to Raoult’s law for the equilibrium vapour pressure of water above a solution. However, a discrepancy between measured values and those predicted by theory could not be explained. Here, we have used a more precise humidity control device to determine equilibrium relative humidity points. The new results are in agreement with Raoult’s law. We also present a simple argument in statistical mechanics demonstrating that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution: Raoult’s Law. The same argument can be extended to the case where solvent and solute molecules are of different size, as is the case with polymers. The results provide a framework for the correct maintenance of the RH surrounding samples.SynopsisThe equilibrium relative humidity values for a number of the most commonly used precipitants in biological macromolecule crystallisation have been measured using a new humidity control device. A simple argument in statistical mechanics demonstrates that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution (Raoult’s Law). The same argument can be extended to the case where solvent and solute molecules are of different size.

scholarly journals The reflection of vapour molecules at a liquid surface

1931 ◽  
Vol 131 (818) ◽  
pp. 554-564 ◽  
Keyword(s):  
Kinetic Theory ◽  
Vapour Pressure ◽  
Liquid Surface ◽  
Unit Area ◽  
Kinetic Theory Of Gases ◽  
Perfect Gas ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour ◽  
First Approximation ◽  
Rate Of Evaporation

The rate of evaporation of a liquid may be calculated from the kinetic theory of gases if it be assumed that all vapour molecules which strike the surface enter the liquid and that, as a first approximation, the vapour behaves as a perfect gas. Under these circumstances, it follows from the kinetic theory of gases that m = mass of molecules leaving unit area per minute = mass of molecules striking unit area per minute from the saturated vapour = 14·63 P s /√T s gram/sq. cm. /min., where P s is the saturated vapour pressure in millimetres of mercury at the surface temperature T s ° A.

Saturated Vapour Pressure and Enthalpy of Sublimation of Nickel

1992 ◽  
Vol 2 (3) ◽  
pp. 97-100 ◽  
Author(s):  
Valerii I. Severing ◽  
Alla V. Tseplayaeva ◽  
Nonna E. Khandamirova ◽  
Yurii A. Priselkov ◽  
Natalya A. Chernova ◽  
...  
Keyword(s):  
Vapour Pressure ◽  
Enthalpy Of Sublimation ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour

Study of temperature dependence of saturated vapour pressure of zirconium(IV) β-diketonates

1996 ◽  
Vol 46 (5) ◽  
pp. 1367-1373 ◽  
Author(s):  
N. B. Morozova ◽  
S. V. Sysoev ◽  
I. K. Igumenov ◽  
A. N. Golubenko
Keyword(s):  
Temperature Dependence ◽  
Vapour Pressure ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour

scholarly journals Sn-Ni-Bi liquid phase thermodynamic properties

2011 ◽  
Vol 9 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Nikolina Milcheva ◽  
Jolanta Romanowska ◽  
Gueorgui Vassilev
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Thermodynamic Properties ◽  
Binary Systems ◽  
Isopiestic Method ◽  
Miscibility Gap ◽  
Calphad Approach ◽  
Activity Data ◽  
General Solution Model ◽  
Good Agreement

AbstractExperimental data of bismuth activity coefficients at 1773 K were obtained by isopiestic method and compared to calculated values. Thermodynamic properties of the Sn-Ni-Bi liquid phase were estimated by means of the general solution model and by the methods of Kohler. Description of the ternary liquid phase (Gibbs excess energy dependence on the temperature and the composition) was achieved by using available thermodynamic data of the constitutive binary systems (Ni-Bi, Sn-Bi, Sn-Ni). A comparison between calculated quantities and experimental data wasconducted. The present assessment with thermodynamically optimized values of the system Sn-Ni-Bi (obtained by the CALPHAD approach) was in good agreement. The suggested appearance of a liquid phase miscibility gap at high temperatures is in agreement with the experimental bismuth activity data and with the assessed thermochemical functions.

Saturated vapour pressure of aroma compounds at various temperatures

2004 ◽  
Vol 85 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Marco Covarrubias-Cervantes ◽  
Ilham Mokbel ◽  
Dominique Champion ◽  
Jacques Jose ◽  
Andrée Voilley
Keyword(s):  
Vapour Pressure ◽  
Aroma Compounds ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour
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