Critical constants and density dependence of the Lorenz–Lorentz coefficient for germane

1978 ◽  
Vol 56 (9) ◽  
pp. 1140-1141 ◽  
Author(s):  
P. Palffy-Muhoray ◽  
D. Balzarini
Keyword(s):  
Critical Temperature ◽  
Density Dependence ◽  
Experimental Error ◽  
Critical Density ◽  
Coexistence Curve ◽  
Index Of Refraction ◽  
Density Range ◽  
Temperature Range ◽  
Critical Constants

The index of refraction at 6328 Å has been measured for germane in the density range 0.15 to 0.9 g/cm3. The temperature and density ranges over which measurements are made are near the coexistence curve. The coefficient in the Lorenz–Lorentz expression, [Formula: see text], is constant to within 0.5% within experimental error for the temperature range and density range studied. The coefficient is slightly higher near the critical density. The critical density is measured to be 0.503 g/cm3. The critical temperature is measured to be 38.92 °C.

Lorentz–Lorenz Coefficient of Ethane

1974 ◽  
Vol 52 (20) ◽  
pp. 2011-2013 ◽  
Author(s):  
M. Burton ◽  
D. Balzarini
Keyword(s):  
Critical Density ◽  
Index Of Refraction ◽  
Density Range

The index of refraction of ethane at 6328 Å has been measured in the density range 0.02 to 0.36 g/cm3(1 to 200 amagats). The coefficient in the Lorentz–Lorenz expression [Formula: see text] is constant to within 0.5% for the temperature and density range studied. The coefficient [Formula: see text] increases with density reaching a maximum near the critical density and decreases with density for densities larger than the critical density. The critical density has been measured in the same experiment and is 0.2062 ± 0.0003 g/cm3.

Density Dependence of Lorentz–Lorenz Coefficient for Sulfur Hexafluoride

1974 ◽  
Vol 52 (20) ◽  
pp. 2007-2010 ◽  
Author(s):  
D. Balzarini ◽  
P. Palffy
Keyword(s):  
High Pressure ◽  
Refractive Index ◽  
Density Dependence ◽  
Sulfur Hexafluoride ◽  
Critical Density ◽  
Small Variation ◽  
Needle Valve ◽  
Density Range ◽  
High Pressure Cell ◽  
Precision Balance

The Lorentz–Lorenz coefficient for sulfur hexafluoride has been measured over the density range 0.1 g/cm3 to 1.3 g/cm3. The critical density has been measured and is 0.736 ± 0.001 g/cm3. Refractive index and density are both measured in the same experiment yielding values of the Lorentz–Lorenz coefficient accurate to 0.05% for densities near critical. The method utilizes a prism-shaped high pressure cell which can be removed from a temperature controlled holder and weighed on a precision balance. The cell is equipped with a needle valve which allows the high pressure gas to be bled out in steps. Refractive index is measured as a function of weight and hence density. Studies of sulfur hexafluoride indicate a small variation of less than 0.5% over the density range covered. A knowledge of the density dependence is necessary for interpretation and verification of the validity of recent experiments near the critical points of pure fluids.

AN INVESTIGATION OF THE HYDROGEN-CHLORIDE-PROPYLENE REACTION IN THE REGION OF THE CRITICAL TEMPERATURE

1938 ◽  
Vol 16b (12) ◽  
pp. 453-467 ◽  
Author(s):  
C. H. Holder ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Temperature Coefficient ◽  
Hydrogen Chloride ◽  
Liquid State ◽  
Critical Density ◽  
Positive Temperature ◽  
Gaseous State ◽  
Gaseous Mixtures ◽  
Reaction Velocity ◽  
Temperature Range

The reaction between hydrogen chloride and propylene has been studied in the gaseous state above the critical temperature and in the liquid state just below the critical temperature. Pressures were used such that the density of the gaseous mixtures could be made as great as the density of the liquid mixture at some temperature.The rate of reaction above the critical temperature increases slowly with increasing pressure until a certain critical density is attained, after which the rate increases rapidly. In the liquid state the reaction has a positive temperature coefficient except for a 25° temperature range just below the critical temperature. In this region there is a rapid decrease in density of the medium with rise in temperature and a negative temperature coefficient occurs.The density of the liquid reactants at a number of temperatures just below the critical temperature (here defined as the temperature where the visible meniscus disappears) has been reproduced above the critical temperature for a small temperature range. The reaction velocity data obtained under these conditions show a minimum in passing through the critical temperature region.The above results have been interpreted on the basis of a "structure" characteristic of the liquid state which favors higher reaction velocity and which may exist above the critical temperature at sufficiently high densities.

ISOTHERMS OF SULPHUR HEXAFLUORIDE IN THE CRITICAL TEMPERATURE REGION

1951 ◽  
Vol 29 (8) ◽  
pp. 699-714 ◽  
Author(s):  
K. E. MacCormack ◽  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Temperature Region ◽  
Critical Density ◽  
Sulphur Hexafluoride ◽  
Small Temperature ◽  
Liquid Meniscus ◽  
Temperature Range ◽  
Horizontal Portion ◽  
Theoretical Considerations ◽  
Finite Slope

Measurements of the P-V isotherms for sulphur hexafluoride in a small temperature range of approximately 1.5°C. in the critical region have been made to determine the validity of some theoretical considerations recently proposed. No evidence has been found to support the postulates of Mayer with respect to anomalous second order transitions over a finite temperature range above the temperature of disappearance of a liquid meniscus designated Tm. All isotherms above the latter are found to have a finite slope and it is not possible to conclude that the Tm isotherm has a finite horizontal portion or "flat top". These conclusions are borne out by the nature of the isometrics which have been plotted and discussed qualitatively in relation to the existing theories.The temperature of meniscus disappearance Tm is estimated to be 45.547 ± 0.003°C. and at the previously determined critical density (1) of 0.7517 gm./cm.3 the corresponding pressure is found to be 37.113 ± 0.003 atm. The critical density was found to be approximately 0.73 gm./cm.3

Density of Perfluorohexane Near the Evaporation Critical Point

2013 ◽  
Vol 8 (1) ◽  
pp. 73-77
Author(s):  
Sergey Stankus ◽  
Rashid Khairulin ◽  
Viktor Martynets ◽  
Yuri Molorodov
Keyword(s):  
Critical Temperature ◽  
Critical Exponent ◽  
Temperature Dependence ◽  
Critical Point ◽  
Gamma Ray ◽  
Coexistence Curve ◽  
Temperature Range ◽  
Gamma Ray Attenuation ◽  
Liquid And Vapor Phases

The density of n-perfluorohexane along the liquid-vapour coexistence curve has been studied by a gamma-ray attenuation technique over the temperature range from 293.83 to 449.18 K. The critical temperature 449.22  0.05 K, the density 613.8  2 kg/m3 , and the critical exponent of coexistence curve 0.349  0.005 were determined. The approximation equations of the temperature dependence of the liquid and vapor phases density were obtained. The results were compared with the data available in the literature. The influence of hydrostatic effect due to the high compressibility of the substance in the vicinity of the vaporization critical point was observed

Optical properties of the Vanadium dioxide

2015 ◽  
Vol 8 (2) ◽  
pp. 2148-2155 ◽  
Author(s):  
Abderrahim Benchaib ◽  
Abdesselam Mdaa ◽  
Izeddine Zorkani ◽  
Anouar Jorio
Keyword(s):  
Energy Efficiency ◽  
Optical Properties ◽  
Critical Temperature ◽  
Thin Layer ◽  
Dielectric Function ◽  
Vanadium Dioxide ◽  
Ultra Violet ◽  
Index Of Refraction ◽  
Practical Utility ◽  
Infra Red

The vanadium dioxide is a material thermo chromium which sees its optical properties changing at the time of the transition from the phase of semiconductor state ↔ metal, at a critical temperature of 68°C. The study of the optical properties of a thin layer of VO₂ thickness 82 nm, such as the dielectric function, the index of refraction, the coefficient ofextinction, the absorption’s coefficient, the reflectivity, the transmittivity, in the photonic spectrum of energy ω located inthe interval: 0.001242 ≤ ω (ev) ≤ 6, enables us to control well its practical utility in various applications, like the intelligentpanes, the photovoltaic, paintings for increasing energy efficiency in buildings, detectors of infra-red (I.R) or ultra-violet(U.V). We will make simulations with Maple and compare our results with those of the literature

Electrochemical studies of the Pb2+/Pb(Hg) system in aqueous and aqueous ethylene glycol solutions

1979 ◽  
Vol 57 (14) ◽  
pp. 1801-1803 ◽  
Author(s):  
Tibor Rabockai
Keyword(s):  
Aqueous Solution ◽  
Ethylene Glycol ◽  
Organic Solvent ◽  
Electrochemical Behavior ◽  
Experimental Error ◽  
Electrochemical Studies ◽  
Temperature Range ◽  
All Solutions ◽  
Aqueous Ethylene Glycol ◽  
Current Reversal

The electrochemical behavior of the Pb2+/Pb(Hg) system in aqueous and aqueous ethylene glycol solutions is studied in the temperature range of 20.0 to 50.0 °C by means of current reversal chronopotentiometry. It is shown that the reduction of Pb2+ ion is reversible and that kinetic or catalytic complications are not present. The value of dE1/2/dT is −0.6 mV/deg in the aqueous solution and −0.5 mV/deg in the solution with 56% (w/w) or higher concentrations of the organic solvent. In the above concentration range of ethylene glycol the activation energies of diffusion and viscosity vary from 4.3 × 103 to 7.2 × 103 cal mol−1 and from 3.7 × 103 to 6.7 × 103 cal mol−1, respectively. For all solutions the solvodynamic mean radius of the diffusing species remains constant within the experimental error, suggesting that the diffusing species is always the hydrated Pb2+ ion.

A STUDY OF THE COEXISTENCE OF THE LIQUID AND GASEOUS STATES OF AGGREGATION IN THE CRITICAL TEMPERATURE REGION. ETHYLENE

1940 ◽  
Vol 18b (4) ◽  
pp. 118-121 ◽  
Author(s):  
S. N. Naldrett ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Temperature Region ◽  
Previous Investigation ◽  
Coexistence Curve

The coexistence curve of ethylene has been determined in a manner similar to that described in a previous investigation on ethane (9). It is found to lie entirely within the coexistence curve determined by P-V-T methods by other investigators (6). This is considered to be evidence for the formation of a dispersion of liquid and vapour before the critical temperature is reached. The term "critical dispersion temperature" is suggested for the temperature at the apex of the coexistence curve determined by the disappearance of the meniscus in a bomb shaken in the manner described in this investigation. The apex of the curve determined by P-V-T methods is the true critical temperature, beyond which liquid is not stable. The classical critical temperature, determined by the disappearance of the meniscus in a stationary bomb, is an indefinite point between these two.

On the NaCl-H2O coexistence curve near the critical temperature of H2O

1989 ◽  
Vol 156 (4) ◽  
pp. 415-417 ◽  
Author(s):  
A.H. Harvey ◽  
J.M.H.Levelt Sengers
Keyword(s):  
Critical Temperature ◽  
Coexistence Curve
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