Thermodynamic Anomalies of a van der Waals Helium–Nitrogen Solution at the Critical Point of Pure Nitrogen

1969 ◽  
Vol 51 (7) ◽  
pp. 2920-2924
Author(s):  
B. J. Dalton ◽  
Robert E. Barieau
Keyword(s):  
Critical Point ◽  
Van Der Waals ◽  
Pure Nitrogen ◽  
Thermodynamic Anomalies

Critical Point of Metals from the van der Waals Model

1971 ◽  
Vol 3 (1) ◽  
pp. 364-371 ◽  
Author(s):  
David A. Young ◽  
Berni J. Alder
Keyword(s):  
Critical Point ◽  
Van Der Waals ◽  
Van Der Waals Model

THE BAROMETRIC FORMULA FOR REAL GASES AND ITS APPLICATION NEAR THE CRITICAL POINT

1933 ◽  
Vol 9 (6) ◽  
pp. 637-640 ◽  
Author(s):  
R. Ruedy
Keyword(s):  
Molecular Weight ◽  
Critical Temperature ◽  
Temperature Gradient ◽  
Critical Point ◽  
Van Der Waals ◽  
Critical Value ◽  
Uniform Density ◽  
Van Der Waals Equation ◽  
Other Substances ◽  
Separation Of Isotopes

According to the theory of the continuity of liquid and gaseous states, as expressed for instance in van der Waals' equation, pronounced density differences may exist in a short column of fluid maintained, throughout its length, at the critical temperature. The point in the tube at which the density of the contents has decreased a given percentage from the critical value is the higher the larger the ratio of the critical temperature to molecular weight. For substances like neon the variations are so large that a measurable separation of isotopes may be expected at or near the critical point; for other substances the computed results are at least of the magnitude found by experiment. Also, according to the theory, in order to obtain, at or near the critical point, a column of gas of uniform density a temperature gradient must be allowed to exist along the column.

scholarly journals The isotherms of CO 2 in the neighbourhood of the critical point and round the coexistence line

1937 ◽  
Vol 160 (902) ◽  
pp. 358-375 ◽  
Keyword(s):  
Critical Point ◽  
Steel Tube ◽  
Pure Nitrogen ◽  
Steel Vessel ◽  
Critical Data ◽  
Diagrammatic Sketch ◽  
New Apparatus ◽  
Coexistence Line ◽  
The One

The isotherms of CO 2 between 0 and 150°C. and up to 3000 atm. have been previously published by two of the authors (Michels, A. and C. 1935). The method used for these measurements was not suitable, however, for determinations in the neighbourhood of the critical point and the coexistence line. A second method has therefore been developed by which both the critical data and the coexistence line can be determined. This method and the results obtained are described in the present paper. The Method and Apparatus The method was based on the one developed by Michels and Nederbragt (1934) for the determination of the condensation points of a binary mixture. While, however, for the measurements of condensation points, it was not necessary to know the quantity of gas in the apparatus, this knowledge is essential for the determination of isotherms. A new apparatus was therefore constructed in which this quantity could be determined. A diagrammatic sketch showing the principle employed is given in fig. 1. In a steel vessel A , a glass bell B is suspended which is connected through the steel valve H and the capillary J to a cylinder containing a supply of the gas to be examined. A steel capillary C connects A with a second steel vessel D , placed on one scale pan of a balance. Inside D a steel tube E , which is coupled to C , reaches to the bottom. The capillary F is connected to the top of D and leads to a cylinder of pure nitrogen and to an apparatus for measuring the gas pressure. The capillaries C and F are flexible, and are supported at G at such a distance from the scale pan that the variations in the forces acting on the latter during the swinging can be neglected. Before starting the measurements, the vessels A , the glass bell B and the tube C are completely, and the vessel D is partly filled with mercury. The valve H is then opened and CO 2 gas admitted to the glass bell, driving mercury out of A into D . The pressure in D is balanced by nitrogen introduced through F . When sufficient CO 2 has entered the glass bell, the valve H is shut. As the filling operation is carried out at a temperature and pressure at which the isotherms of CO 2 are known, the amount of gas in B can be calculated from a knowledge of the volume.

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