Miscibility phase diagram

Veatch SL, Keller SL. Miscibility phase diagrams of giant vesicles containing sphingomyelin. Phys. Rev. Lett. 2005 94 1481011— 1481014. 

Fig. 20 Miscibility phase diagram (wt%) as a function of temperature (°C) between A/,A/-bis-(D-mannitolyl)dodecylamide (A) and octadecanoyl D-galactocerebroside (B).

Figure 25.13 The isotherms of pressure p versus molar volume V for carbon dioxide. The broken line is the phase diagram. Like a miscibility phase diagram, this is concave downward, and has a critical point at the top. Inside the dashed region, the system is boiling. Source A) Walton, Three Phases of Matter, Oxford University Press, New York, 1983. 

A polymier molecule is much larger than a typical small solvent molecule, often by more than a thousandfold. This difference in size has important consequences for the thermodynamics of pol>mier solutions. First, the coUigative attraction of a polymer solution for soWent small-molecule molecules is much higher than would be expected on the basis of the mole fractions. Rather the attraction is proportional to the volume fraction. Second, polymers are typically not miscible with other pol miers because of small mixing entropies. Third, the size as>Tnmetry between a polymer and a small-molecule solvent translates into an asymmetry in miscibility phase diagrams. 

Sodium is miscible with many metals in liquid phase and forms alloys or compounds. Important examples ate hsted in Table 9 phase diagrams ate available... 

Tellurium Sulfide. In the hquid state, teUurium is completely miscible with sulfur. The Te—S phase diagram shows a eutectic at 105—110°C when the sulfur content is 98—99 atom % (94—98 wt %). TeUurium—sulfur aUoys have semiconductor properties (see Semiconductors). Bands attributed to teUurium sulfide [16608-21 -2] TeS, molecules have been observed. 

Carbon disulfide is completely miscible with many hydrocarbons, alcohols, and chlorinated hydrocarbons (9,13). Phosphoms (14) and sulfur are very soluble in carbon disulfide. Sulfur reaches a maximum solubiUty of 63% S at the 60°C atmospheric boiling point of the solution (15). SolubiUty data for carbon disulfide in Hquid sulfur at a CS2 partial pressure of 101 kPa (1 atm) and a phase diagram for the sulfur—carbon disulfide system have been published (16). Vapor—Hquid equiHbrium and freezing point data ate available for several binary mixtures containing carbon disulfide (9). 

Fig. 6. Boiling point (a) and phase diagram (b) for the heterogeneous a2eotropic system, water/ 1-butanol at atmospheric pressure, yi, B and C, D are representative equiUbrium points Z is the a2eotropic point M and N are Hquid miscibility limits.

The Pb-Sn system has a eutectic. Look at the Pb-Sn phase diagram (Fig. AT. 26). Above i27°C., liquid lead and liquid tin are completely miscible, that is, the one dissolves in the other completely. On cooling, solid first starts to appear when the lines (or boundaries) which limit the bottom of the liquid field are reached. 

HF is miscible with water in all proportions and the phase diagram (Fig. 17.4a) shows the presence of three compounds H2O.HF (mp — 35.5°), H2O.2HF (mp-75.5°) and H2O.4HF (mp — 100.4°, i.e. 17° below the mp of pure HF). Recent X-ray studies have confirmed earlier conjectures that these compounds are best formulated as H-bonded oxonium salts [HsOJF, [H30][HF2], and [H30][H3F4] with three very strong H bonds per oxonium ion and average O - - F distances of 246.7, 250.2... 

Of course, LC is not often carried out with neat mobile-phase fluids. As we blend solvents we must pay attention to the phase behavior of the mixtures we produce. This adds complexity to the picture, but the same basic concepts still hold we need to define the region in the phase diagram where we have continuous behavior and only one fluid state. For a two-component mixture, the complete phase diagram requires three dimensions, as shown in Figure 7.2. This figure represents a Type I mixture, meaning the two components are miscible as liquids. There are numerous other mixture types (21), many with miscibility gaps between the components, but for our purposes the Type I mixture is Sufficient. 

We have recently shown that the hydrophobic hexafluorophosphate ILs can in fact be made totally miscible with water by addition of alcohols [47, 48] the ternary phase diagram for [BMIM][PF(3]/water/ethanol (left part of Figure 3.3-7) shows the... 

Figure 10.7 The phase diagram (a) and the glass transition temperatures (b) of a PSC/PVME mixture obtained, respectively, by light scattering and differential scanning calorimetry (DSC). Irradiation experiments were performed in the miscible region at 127 C indicated by (X) in the figure of trans-cinnamic acid-labeled polystyrene/poly(vinyl methyl ether) blends.

Liquid-Fluid Equilibria Nearly all binary liquid-fluid phase diagrams can be conveniently placed in one of six classes (Prausnitz, Licntenthaler, and de Azevedo, Molecular Thermodynamics of Fluid Phase Blquilibria, 3d ed., Prentice-Hall, Upper Saddle River, N.J., 1998). Two-phase regions are represented by an area and three-phase regions by a line. In class I, the two components are completely miscible, and a single critical mixture curve connects their criticsu points. Other classes may include intersections between three phase lines and critical curves. For a ternary wstem, the slopes of the tie lines (distribution coefficients) and the size of the two-phase region can vary significantly with pressure as well as temperature due to the compressibility of the solvent. 

The phase diagram for aluminum/silicon (Fig. 4.5) is a typical example of a system of two components that form neither solid solutions (except for very low concentrations) nor a compound with one another, but are miscible in the liquid state. As a special feature an acute minimum is observed in the diagram, the eutectic point. It marks the melting point of the eutectic mixture, which is the mixture which has a lower melting point than either of the pure components or any other mixture. The eutectic line is the horizontal line that passes through the eutectic point. The area underneath is a region in which both components coexist as solids, i.e. in two phases. 

Figure 10.4 Idealized phase diagram for pairs of polymers that form miscible biends at intermediate temperatures...

A convenient starting point is to consult the phase diagrams in Hansen s Constitution of Binary Alloys (10) and supplementary volumes (11,12), but information may also be needed on miscibility at the temperatures normally employed for film preparation and catalytic reaction. Therefore, some consideration must be given to the thermodynamic properties of the... 

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