Concentration-temperature diagram mixture

Concentration-Temperature Diagram.—In this diagram the temperatures are taken as the abscissae, and the composition of the solution, expressed in atoms of chlorine to one atom of iodine, is represented by the ordinates. In the diagram, A represents the melting-point of pure iodine, 114°. If chlorine is added to the system, a solution of chlorine in liquid iodine is obtained, and the temperature at which solid iodine is in equilibrium with the liquid solution will be all the lower the greater the concentration of the chlorine. We therefore obtain the curve ABF, which represents the composition of the solution with which solid iodine is in equilibrium at different temperatures. This curve can be followed down to 0°, but at temperatures below 7 9 (B) it represents metastable equilibria. At B iodine monochloride can be formed, and if present the system becomes invariant B is therefore a quadruple point at which the four phases, iodine, iodine monochloride, solution, and vapour, can co-exist. Continued withdrawal of heat at this point will therefore lead to the complete solidification of the solution to a mixture or conglomerate of iodine and iodine monochloride, while the temperature remains constant during the process. B is the eutectic point for iodine and iodine monochloride. 

Fig. 4 Concentration-Temperature diagram of mixture of two LCs (PAA-PAP), reproduced from E.C. HSU and J.F. Johnson, Mol. Cryst Liq. Cryst 20.177-183 (1973) (with permission Gordon and Breach).

Mixtures of soap in water exhibit a rich variety of phase stmctures, depending on temperature and concentration of the mixture (2). Phase diagrams chart the phase... 

Figure 4.7a shows the temperature-concentration phase diagram for the system naphthalene-/ -naphthol, which forms a continuous series of solid solutions. The melting points of pure naphthalene and -naphthol are 80 and 120 °C, respectively. The upper curve is the liquidus or freezing point curve, the lower the solidus or melting point curve. Any system represented by a point above the liquidus is completely molten, and any point below the solidus represents a completely solidified mass. A point within the area enclosed by the liquidus and solidus curves indicates an equilibrium mixture of liquid and solid solution. Point X, for instance, denotes a liquid of composition L in equilibrium with a solid solution of composition S, and point Y a liquid F in equilibrium with a solid S. ... 

Figure 4 Schematic diagram showing the pressure-temperature behavior for a carbon dioxide / solvent / polymer mixture as a function of carbon dioxide concentration. The diagram shows both the low-temperature (UCST) and the high-temperature (LCST) regions of liquid-liquid immiscibility.

Figure 4.13. Phase diagram as a function of temperature (T) and Marlowet EM50 ethoxylated alcohol surfactant concentration (y) in mixtures of water and decane plus soybean oil. The overall oil-to-water ratio is fixed (a = 0.5), while the ratio of soybean oil to decane is systematically varied from = 0 (100% decane, fi.sh on left side of phase diagram) to = 1 (100% soybean oil fish on upper right side of phase diagram). The path of X(r, y) is shown by squares and the dashed line (from Lade (73))...

Materials can change their phase as a function of a variety of different thermodynamic variables, such as temperature, pressure, volume, or concentration in a mixture. A diagram of this phase behavior, or phase diagram, can be constructed by plotting the parameter ranges over... 

So far we have considered only a single component. However, reservoir fluids contain a mixture of hundreds of components, which adds to the complexity of the phase behaviour. Now consider the impact of adding one component to the ethane, say n-heptane (C7H.,g). We are now discussing a binary (two component) mixture, and will concentrate on the pressure-temperature phase diagram. 

Figure A3.3.2 A schematic phase diagram for a typical binary mixture showmg stable, unstable and metastable regions according to a van der Waals mean field description. The coexistence curve (outer curve) and the spinodal curve (iimer curve) meet at the (upper) critical pomt. A critical quench corresponds to a sudden decrease in temperature along a constant order parameter (concentration) path passing through the critical point. Other constant order parameter paths ending within tire coexistence curve are called off-critical quenches.

Glassification of Phase Boundaries for Binary Systems. Six classes of binary diagrams have been identified. These are shown schematically in Figure 6. Classifications are typically based on pressure—temperature (P T) projections of mixture critical curves and three-phase equiHbria lines (1,5,22,23). Experimental data are usually obtained by a simple synthetic method in which the pressure and temperature of a homogeneous solution of known concentration are manipulated to precipitate a visually observed phase. 

Solubility. Sohd—Hquid equihbrium, or the solubiHty of a chemical compound in a solvent, refers to the amount of solute that can be dissolved at constant temperature, pressure, and system composition in other words, the maximum concentration of the solute in the solvent at static conditions. In a system consisting of a solute and a solvent, specifying system temperature and pressure fixes ah. other intensive variables. In particular, the composition of each of the two phases is fixed, and solubiHty diagrams of the type shown for a hypothetical mixture of R and S in Figure 2 can be constmcted. Such a system is said to form an eutectic, ie, there is a condition at which both R and S crystallize into a soHd phase at a fixed ratio that is identical to their ratio in solution. Consequently, there is no change in the composition of residual Hquor as a result of crystallization. 

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