Pressure-temperature diagram Probability

Modern society probably depends more upon the combustion of hydrocarbons than upon any other chemical reaction. The various applications of hydrocarbon combustion were recently described [1] in terms of a typical temperature—pressure ignition diagram for a hydrocarbon + oxygen (or air) mixture, as shown in Fig. 1. 

Class B1 systems show closed loop vapour/liquid pressure/composition diagrams in the vapour liquid region at all temperatures between the solvent critical temperature and the critical temperature of the heavy component. The system ethane/methanol shows this behaviour. Carbon dioxide/w-hexadecane is probably also of this type (Figure 1.10 and 1.11). 

The same figure also shows the pressure—temperature history of a two-phase test run. This run is represented by the series of points J through P. The points are located as described in the preceding section, with the inlet and outlet of the test section being points L and N, respectively. The interesting feature of this diagram is that somewhere in the test section (between points LandN) the fluid flow became two-phase. This is represented as point M, which is the intersection of the saturation line and the arbitrary extension of line KL. As constructed, point M is arbitrarily located and would probably be better located by the intersection of the saturation line and a vertical line through point , as shown by point iW. The temperature decrease from M (or A/ ) is due to the evaporation of the liquid, where the latent heat of evaporation is used to cool the fluid. 

P. W. Bridgman, etc.—and J. Kendall and M. L. Landon obtained 146 9 +0 5°-P. W. Bridgman found that as in the case of potassium hydrosulphate, there are four modifications of the ammonium salt, and very probably yet a fifth form. The temperature-pressure diagram is illustrated in Fig. 59 and some data in Table XLIII. 

Several water compositions are plotted on the stability diagrams in Figure 8.2. It can be seen that at shallow Earth surface pressures and temperatures, seawater plots in the stability field of dolomite whereas solutions of average river water composition and most shallow groundwaters plot in the field of calcite. With burial of carbonate sediments and elevated P and T, the dolomite field shrinks, but subsurface fluid compositions evolve toward a composition in equilibrium with dolomite. This conclusion is probably one of the most important arguments for the formation of dolomite during deep burial diagenesis (see also Hardie, 1987). Thermodynamic considerations favor this reaction path, as well as the fact that... 

Figure 10. Phase diagram of the Cr-N system [10] with recent results on the homogeneity ranges of Cr2N and CrNi v The homogeneity range of the latter broadens substantially upon increasing temperature. The nitrogen-rich phase boundary of CrN c is for 30 bar N2 and extends most probably at least up to 50 at-% N at higher pressures.

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