Temperature scaling, equilibrium phase diagrams

Phase diagram of water (not to scale). The curves and line represent the temperatures and pressures at which phases are in equilibrium. The triple point is at 0.0rC, 4.56 mm Hg the critical point is at 374°C. 

Fig. 2. Logarithmic activity diagram depicting equilibrium phase relations among aluminosilicates and sea water in an idealized nine-component model of tire ocean system at the noted temperatures, one atmosphere total pressure, and unit activity of H20. The shaded area represents (lie composition range of sea water at the specified temperature, and the dot-dash lines indicate the composition of sea water saturated with quartz, amotphous silica, and sepiolite, respectively. The scale to the left of the diagram refers to calcite saturation foi different fugacities of CO2. The dashed contours designate the composition (in % illite) of a mixed-layer illitcmontmorillonitc solid solution phase in equilibrium with sea water (from Helgesun, H, C. and Mackenzie, F T.. 1970. Silicate-sea water equilibria in the ocean system Deep Sea Res.).

For simplicity, we consider here only a binary mixtures (A, B) and do not discuss the complications posed by extensions to multicomponent systems. Figure 1 shows a schematic phase diagram in the plane of variables temperature T and concentration c of species B. Kinetics of phase separation in bulk fluid mixtures is triggered by a rapid quench (at time t = 0) from the one-phase region into the miscibility gap. The initial equilibrium state (f < 0) is spatially homogeneous, apart from small-scale concentration inhomogeneities. The final equilibrium state towards which the system ultimately evolves (t oo) consists of... 

Another important projection of the PvT-diagram is the PT-graph (see Figure 2.5). In this projection, the dew-point line coincides with the boiling point in the vapor pressure curve. Similarly, solidus and liquidus curve coincide in the melting curve. The phase transition between the solid state and the gaseous state is described by the sublimation curve. Vapor pressure curve, melting curve, and sublimation curve meet at the triple point, where the three phases vapor, liquid, and solid coexist in equilibrium. The triple point of water is very well known and can be reproduced in a so-called triple point cell. It is used as a fix point of the International Temperature Scale ITS-90 [4] (Tt, = 273.16 K or = 0.01"C, Ptr = 611.657 0.01 Pa). The vapor pressure curve ends at the critical point no liquid exists above the critical temperature T. ... 

FIG. 7 The unary C12MG phase diagram manifold. The temperature scale is to the left (outside the diagram). Each arm corresponds to a particular crystal structure the left arm is the equilibrium diagram. The transformations that occur among polymorphs are indicated by dashed arrows. 

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