Pure substances: Elements and compounds

2019 ◽  
pp. 95-105
Author(s):  
Keith S. Taber
Keyword(s):  
Pure Substances

Correlation of Melting Results for Both Pure Substances and Impure Substances

1986 ◽  
Vol 108 (3) ◽  
pp. 649-653 ◽  
Author(s):  
E. M. Sparrow ◽  
G. A. Gurtcheff ◽  
T. A. Myrum
Keyword(s):  
Solid Phase ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Vertical Tube ◽  
Step Change ◽  
Pure Substance ◽  
Characteristic Temperatures ◽  
Pure Substances ◽  
T Values ◽  
Melting Experiments

Melting experiments were performed encompassing both pure and impure substances. The pure substances included n-octadecane paraffin and n-eicosane paraffin, while the impure substances were mixtures synthesized from the pure paraffins. The experiments were carried out in a closed vertical tube whose wall was subjected to a step-change increase in temperature to initiate the melting. For each impure substance, supplementary measurements were made of two characteristic temperatures: the temperature T** at which melting of the solid phase first begins and the lowest temperature T* at which the melting can go to completion. For a pure substance, T** = T*. The time-dependent melting results for all the investigated substances, both pure and impure, were well correlated as a function of FoSte**(Gr**)1/8 alone, where the ** signifies the presence of T** in the temperature difference which appears in Ste and Gr. This correlation enables melting rates for impure substances to be determined from melting rates for pure substances. The T** values needed for the implementation of the correlation can be obtained from simple experiments, obviating the need for the complete equilibrium phase diagram.

EQUATIONS OF STATE FOR FLUIDS: THE LIQUID-VAPOR EQUILIBRIUM (LVE)

2008 ◽  
Vol 22 (30) ◽  
pp. 5335-5347 ◽  
Author(s):  
JIANXIANG TIAN ◽  
YUANXING GUI
Keyword(s):  
Experimental Data ◽  
Equations Of State ◽  
Packing Fraction ◽  
Optimal Choice ◽  
Critical Conditions ◽  
Mechanics Model ◽  
Vapor Equilibrium ◽  
Pure Substances ◽  
Compressibility Factors ◽  
Liquid Vapor

Historically, the development of equations of state for fluids has almost invariably followed the lead of the van der Waals (vdW) equation which includes an attraction term and a repulsion term. In this paper, using a simple statistical mechanics model, we introduce a parameter σ as both the power and a coefficient of the packing fraction y which locates at the numerator of the vdW attraction term. Then nine equations of state are constructed to solve the critical conditions and the main thermodynamic properties of pure substances at liquid-vapor equilibrium. As a result, the correct critical compressibility factors of Nitrogen, Argon, Carbon dioxide, Ethene, Methane, Oxygen, Propene, Water and Hydrogen, are obtained with an optimal choice of parameter σ. Good predictions of these equations to the liquid-vapor equilibrium properties below critical temperature are reported and compared with experimental data.

scholarly journals Isolation of Highly Pure Substances from Essential Oils: Efficiency Improvement by Combination of Different Thermal Separation Processes

2012 ◽  
Vol 84 (8) ◽  
pp. 1350-1350
Author(s):  
C. Jurischka ◽  
C. Stollberg ◽  
M. Smieszek ◽  
P. Ay ◽  
M. Kay ◽  
...  
Keyword(s):  
Essential Oils ◽  
Efficiency Improvement ◽  
Separation Processes ◽  
Pure Substances

XLII.—The Atomic Weight of Platinum

1909 ◽  
Vol 29 ◽  
pp. 721-747 ◽  
Author(s):  
E. H. Archibald
Keyword(s):  
Atomic Weight ◽  
Pure Substances

Twenty-two years have passed since the atomic weight of platinum was studied by Dittmar and M'Arthur. This is the last investigation recorded which has been concerned with the value of this constant.During the intervening period, as the result of many investigations carried on by Professor T. W. Richards and his students, the accuracy with which many of the’ manipulations incident to atomic weight investigations can be executed has been greatly increased. Perhaps of still greater importance, methods for the preparation of many compounds of undoubted purity have been devised, and the principles underlying the preparation of pure substances have been clearly set forth.

Prediction of normal melting point of pure substances by a reference series method

AIChE Journal ◽  
2013 ◽  
Vol 59 (10) ◽  
pp. 3730-3740 ◽  
Author(s):  
Neima Brauner ◽  
Mordechai Shacham
Keyword(s):  
Melting Point ◽  
Series Method ◽  
Reference Series ◽  
Pure Substances ◽  
Normal Melting Point

EXPERIMENTAL STUDIES OF SOLUTION PROCESSES: VI. EFFECT OF SOLVENT ON INFRARED ABSORPTION SPECTRA

1960 ◽  
Vol 38 (10) ◽  
pp. 1921-1926 ◽  
Author(s):  
P. A. D. De Maine ◽  
L. H. Daly ◽  
M. M. De Maine
Keyword(s):  
Infrared Absorption ◽  
Experimental Studies ◽  
Absorption Data ◽  
Frequency Shifts ◽  
Extinction Coefficients ◽  
Effect Of Solvent ◽  
Solution Processes ◽  
Pure Substances ◽  
Infrared Absorption Spectra ◽  
Molar Extinction Coefficients

Here are reported infrared absorption data between 4000 cm−1 and 700 cm−1 near 19 °C for methanol, n-propanol, isopropanol, cyclohexanol, benzyl alcohol, diethyl ether, anisole, 1,4-dioxane, diisopropyl ether, nitromethane, acetone, p-xylene, benzene, and hexane as pure substances and in carbon tetrachloride solution. Band frequencies accurate to within 1 cm−1 are reported. Except for the 3340 cm−1 band in dilute MeOH solutions no frequency shifts were observed even with gross changes of the electrical properties of the solutions. Molar extinction coefficients at absorption maxima are discussed briefly.

scholarly journals Thermal Analysis and Optimization of the Phase Diagram of the Cu-Ag Sulfide System

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 593
Author(s):  
Fiseha Tesfaye ◽  
Daniel Lindberg ◽  
Dmitry Sukhomlinov ◽  
Pekka Taskinen ◽  
Leena Hupa
Keyword(s):  
Phase Diagram ◽  
Inert Atmosphere ◽  
Thermodynamic Quantities ◽  
Thermal Stabilities ◽  
High Temperature Reaction ◽  
Fusion Data ◽  
Measurement Results ◽  
Pure Substances ◽  
Factsage Software ◽  
First Time

Thermal stabilities of selected ternary phases of industrial interest in the Ag-Cu-S system have been studied by the calorimetric and electromotive force techniques. The ternary compounds Ag1.2Cu0.8S (mineral mackinstryite) and AgCuS (mineral stromeyerite) were equilibrated through high-temperature reaction of the pure Cu2S and Ag2S in an inert atmosphere. The synthesized single solid sample constituting the two ternary phases was ground into fine powders and lightly pressed into pellets before calorimetric measurements. An electrochemical cell incorporating the two equilibrated phase and additional CuS as a cathode material was employed. The measurement results obtained with both techniques were analyzed and thermodynamic properties in the system have been determined and compared with the available literature values. Enthalpy of fusion data of the Ag-richer solid solution (Ag,Cu)2S have also been determined directly from the experimental data for the first time. The thermodynamic quantities determined in this work can be used to calculate thermal energy of processes involving the Ag-Cu-S-ternary phases. By applying the obtained results and the critically evaluated literature data, we have developed a thermodynamic database. The self-developed database was combined with the latest pure substances database of the FactSage software package to model the phase diagram of the Ag2S-Cu2S system.

scholarly journals Selective Removal of Hydrogen Sulphide from Industrial Gas Mixtures Using Zeolite NaA

2017 ◽  
Vol 45 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Tamás Kristóf
Keyword(s):  
Hydrogen Sulphide ◽  
Gas Mixtures ◽  
Adsorption Properties ◽  
Intermolecular Potential ◽  
Grand Canonical Monte Carlo ◽  
Potential Models ◽  
Zeolite Naa ◽  
Pure Substances ◽  
Grand Canonical ◽  
Very High

Abstract Hydrogen sulphide removal from simple gas mixtures using a highly polar zeolite was studied by molecular simulation. The equilibrium adsorption properties of hydrogen sulphide, hydrogen, methane and their mixtures on dehydrated zeolite NaA were computed by Grand Canonical Monte Carlo simulations. Existing all-atom intermolecular potential models were optimized to reproduce the adsorption isotherms of the pure substances. The adsorption results of the mixture, also confirmed by IAST calculations, showed very high selectivities of hydrogen sulphide to the investigated non-polar gases, predicting an outstanding performance of zeolite NaA in technological applications that target hydrogen sulphide capture.

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