COEXISTENCE PHENOMENA IN THE CRITICAL REGION: III. COMPRESSIBILITY OF ETHYLENE AND XENON FROM LIGHT SCATTERING

1955 ◽  
Vol 33 (9) ◽  
pp. 1399-1407 ◽  
Author(s):  
F. E. Murray ◽  
S. G. Mason
Keyword(s):  
Critical Temperature ◽  
Light Scattering ◽  
Critical Region ◽  
Variable Function

Turbidity measurements in the region immediately above the critical temperature are used to calculate values of (∂p/∂ν)T These results show that (∂p/∂ν)T is a continuously variable function of the density to within 0.02 °C. above the critical temperature. The experiments indicate that there exists no region above Tc throughout which (∂p/∂ν)T = 0 in ethylene or xenon.

Hard-to-soft transition of transparent shape memory gels and the first observation of their critical temperature studied with scanning microscopic light scattering

2013 ◽  
Vol 108 ◽  
pp. 239-242 ◽  
Author(s):  
M. Hasnat Kabir ◽  
Jin Gong ◽  
Yosuke Watanabe ◽  
Masato Makino ◽  
Hidemitsu Furukawa
Keyword(s):  
Critical Temperature ◽  
Light Scattering ◽  
Shape Memory

ON THE LIQUID–VAPOR COEXISTENCE CURVE OF XENON IN THE REGION OF THE CRITICAL TEMPERATURE

1952 ◽  
Vol 30 (5) ◽  
pp. 422-437 ◽  
Author(s):  
M. A. Weinberger ◽  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Critical Region ◽  
Van Der Waals ◽  
Coexistence Curve ◽  
Packing Materials ◽  
Critical Data ◽  
Van Der Waals Theory ◽  
Liquid Vapor

The liquid–vapor coexistence curves of very pure xenon have been determined in bombs of vertical lengths 1.2 cm. and 19 cm. The longer bomb yielded a flat-topped coexistence curve, the shorter a more rounded curve. The classical van der Waals theory is capable of explaining a large portion of the flat top if effects of gravity are taken into account. Details of the theoretical variation of the width of the flat top with vertical bomb lengths are given. The critical data obtained for xenon are ρc = 1.105 gm./cc., Tc = 16.590 ±.001 °C. The danger of contamination of gases in the critical region on contact with gasket or packing materials is stressed.

The measurements of coexistence curves and light scattering for {xC6H5CN+(1−x)CH3(CH2)10CH3} in the critical region

2008 ◽  
Vol 40 (3) ◽  
pp. 424-430 ◽  
Author(s):  
Chunfeng Mao ◽  
Nong Wang ◽  
Xuhong Peng ◽  
Xueqin An ◽  
Weiguo Shen
Keyword(s):  
Light Scattering ◽  
Critical Region

Light Scattering in the Critical Region. I. Ethylene

1950 ◽  
Vol 18 (5) ◽  
pp. 650-654 ◽  
Author(s):  
H. A. Cataldi ◽  
H. G. Drickamer
Keyword(s):  
Light Scattering ◽  
Critical Region ◽  
Region I

Light Scattering and Shear Viscosity Studies of the Binary System 2,6‐Lutidine‐Water in the Critical Region

1972 ◽  
Vol 56 (12) ◽  
pp. 6169-6179 ◽  
Author(s):  
Erdoḡan Gülari ◽  
A. F. Collings ◽  
R. L. Schmidt ◽  
C. J. Pings
Keyword(s):  
Light Scattering ◽  
Binary System ◽  
Shear Viscosity ◽  
Critical Region

THE VISCOSITY OF CARBON DIOXIDE IN THE CRITICAL REGION

1940 ◽  
Vol 18b (10) ◽  
pp. 322-332 ◽  
Author(s):  
S. N. Naldrett ◽  
O. Maass
Keyword(s):  
Carbon Dioxide ◽  
Critical Temperature ◽  
Lower Limit ◽  
Critical Region ◽  
Liquid State ◽  
Condensation Temperature ◽  
Constant Density ◽  
Time Lags ◽  
Great Precision ◽  
Temperature Time

Measurements of the viscosity of carbon dioxide in the critical region have been made with great precision by means of an oscillating disc viscosimeter. The variation of viscosity with temperature at constant density has been determined for 14 different densities. Isothermals have been evaluated from a plot of the isochores. One isothermal was determined directly and is in agreement with those determined indirectly.The form of the viscosity-temperature isochores is not the same as that found by Mason and Maass (12) for ethylene, in that there is no minimum at the critical temperature nor even up to 7 °C. above. For the region just above the condensation temperature, the viscosity is more dependent on density than on temperature; the isochores are almost flat and are well separated. However, the isothermals are spread between an upper and a lower limit of density, showing that viscosity is not entirely independent of temperature. Time lags were observed in the present investigation in the opposite direction to those observed by Geddes and Maass (9); this would appear to decrease the strength of their claims that the time lags that they observed are due to the formation of a structure in the liquid state.

Diffusion of a solute in dilute solution in a supercritical fluid

1991 ◽  
Vol 433 (1887) ◽  
pp. 63-79 ◽  
Keyword(s):  
Diffusion Coefficient ◽  
Critical Temperature ◽  
Equation Of State ◽  
Supercritical Fluid ◽  
Critical Region ◽  
Critical Density ◽  
Partial Molar Volumes ◽  
Dilute Solution ◽  
Binary Diffusion Coefficient ◽  
Binary Diffusion

The experimental evidence for the behaviour of the binary diffusion coefficient for a solute in dilute solution in a supercritical fluid (a fluid above its critical temperature and pressure) is reviewed. Measurements at very low dilution, particularly by the Taylor dispersion technique, indicate that, at constant temperature a few degrees above the critical temperature, the product of density and the diffusion coefficient exhibits a small, continuous and undramatic variation from zero density to well above the critical density. However, some measurements made at higher, but still very low concentrations (e.g. with mole fractions around 10 -3 ), show a lowering of the coefficient in the critical region. The equations, based on non-equilibrium thermodynamics, are put into a form in which the behaviour of the binary diffusion coefficient in the critical region, but not very close to the critical point, may be examined using an equation of state. Calculations for naphthalene in solution in carbon dioxide are carried out using the van der Waals equation of state for mixtures to indicate the form and order of magnitude of the ‘anomalous’ lowering of the coefficient, and especially its dependence on concentration. These indicate a substantial effect even at naphthalene mole fractions of 4.0 x 10 -4 or less and a temperatures 1, 3 and 9 K above the critical temperature of the pure solvent. In addition the flux of a solute in a supercritical fluid in the critical region with respect to space or cell-fixed coordinates is discussed. Because of the large and negative partial molar volumes of solutes like naphthalene in this region, the frames of reference, according to which the diffusion coefficients are defined, can be caused to move rapidly, commonly towards the source of concentration. Thus fluxes of solute with respect to space-fixed coordinates are further substantially reduced in the critical region. The combination of the lowering of the diffusion coefficient and barycentric motion can therefore cause a very significant reduction of solute mass transfer in the critical region and may be the explanation of the sometimes very large diffusion anomalies observed experimentally.

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