Mixtures nitrogen-argon

In gas separation with membranes, a gas mixture at an elevated pressure is passed across the surface of a membrane that is selectively permeable to one component of the mixture. The basic process is illustrated in Figure 16.4. Major current applications of gas separation membranes include the separation of hydrogen from nitrogen, argon and methane in ammonia plants the production of nitrogen from ah and the separation of carbon dioxide from methane in natural gas operations. Membrane gas separation is an area of considerable research interest and the number of applications is expanding rapidly. 

At many plants, fluxes are added to the metal to reduce hydrogen contamination, remove oxides, and eliminate undesirable trace elements. Solid fluxes such as hexachloroethane, aluminum chloride, and anhydrous magnesium chloride may be used, but it is more common to bubble gases such as chlorine, nitrogen, argon, helium, and mixtures of chlorine and inert gases through the molten metal. 

The electron capture detector is another type of ionization detector. Specifically, it utilizes the beta emissions of a radioactive source, often nickel-63, to cause the ionization of the carrier gas molecules, thus generating electrons that constitute an electrical current. As an electrophilic component, such as a pesticide, from the separated mixture enters this detector, the electrons from the carrier gas ionization are captured, creating an alteration in the current flow in an external circuit. This alteration is the source of the electrical signal that is amplified and sent on to the recorder. A diagram of this detector is shown in Figure 12.13. The carrier gas for this detector is either pure nitrogen or a mixture of argon and methane. 

Measurements have so far been made on mixtures of steam + hydrogen, nitrogen, argon, methane, carbon-dioxide, n-hexane, n-heptane, benzene and cyclohexane. The measurements cover the range 373 to 698 K at pressures from 0.1 MPa to saturation or 12.5 MPa. The only exception to this is steam + carbon dioxide for which the measurements extend up to 5.5 MPa. The accuracy of the measurements is around 2 percent. 

Later studies showed the same phenomena in deuterium and deuterium-rare gas mixtures [335, 338, 305], and also in nitrogen and nitrogen-helium mixtures [336] in nitrogen-argon mixtures the feature is, however, not well developed. The intercollisional dip (as the feature is now commonly called) in the rototranslational spectra was identified many years later see Fig. 3.5 and related discussions. The phenomenon was explained by van Kranendonk [404] as a many-body process, in terms of the correlations of induced dipoles in consecutive collisions. In other words, at low densities, the dipole autocorrelation function has a significant negative tail of a characteristic decay time equal to the mean time between collisions see the theoretical developments in Chapter 5 for details. 

The first experimental evidence for the noble gases was obtained by Henry Cavendish in 1766. In a series of experiments on air, he was able to sequentially remove nitrogen (then known as phlogisticated air ), oxygen ( dephlogisticated air ), and carbon dioxide ( fixed air ) from air by chemical means, but a small residue, no more than one part in 120, resisted all attempts at reaction. The nature of Cavendish s unreactive fraction of air remained a mystery for more than a century. This fraction was, of course, eventually shown to be a mixture of argon and other noble gases. ... 

FIG. 2-5 Pressure-enthalpy diagram for dry air. Properties computed with the NIST REFPROP Database, Version 7.0 (Lemmon, E. W., McLinden, M. O., and Huber, M. L., 2002, NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties—REFPROP, Version 7.0, Standard Reference Data Program, National Institute of Standards and Technology), based on the equation of state of Lemmon, E. W., Jacobsen, R. T., Penoncello, S. G., and Friend, D. G., Thermodynamic Properties of Air and Mixtures of Nitrogen, Argon, and Oxygen from 60 to 2000 K at Pressures to 2000 MPa, /, Phys. Chem. Ref. Data 29 331-385, 2000. 

Measurements of the velocity and position of detonation of acetylene, hydrogen, and pentane with oxygen, nitrogen, argon, and carbon dioxide mixtures at initial pressures up to 6 atmospheres were also made.107 The presence of antiknock compounds was found not to atfect the position of detonation. Lead tetramethyl delayed the rate of combustion of pentane, however.lli8,48... 

A typical 100-watt light bulb contains a mixture of argon gas and nitrogen gas. In a light bulb with a total gas pressure of 111 kPa, enough argon is present to yield a partial pressure of 102 kPa. What is the partial pressure of the nitrogen gas ... 

---