Liquid diagram

The more components in a system, the more complex are the phase equilibria and it is more difficult to represent phases graphically. Descriptions of multi-component solid-liquid diagrams and their uses have been given by Mullin 3, Findlay and Campbell , Ricci , Null(10) and Nyvlt 11 1 and techniques for predicting multi-component solid-liquid phase equilibria have been presented by Hormeyer et alS12 Kusik el al.(n), and Sander et al.(U). 

The limiting linear behavior of the ideal P-xeq liquid diagram was previously described in Section 7.3.1. The corresponding P-xeap vapor curve can be added to give the full P-xB diagram for an ideal solution as follows ... 

To explain the very different behavior of real gases, the model must be modified. Suppose the molecular volume is small but not negligible. In stales of high compression, where the total molecular volume becomes of the order of the volume available 10 the gas. the free space available to the molecules is only a Traction of what it would be in a perfect gas. and thus the real gas is much harder to compress than Ihe perfect gas. This explains the low compressibility of dense gases and liquids (diagram). 

In practice, the presence of other aromatics signiheantiy affects the solid/liquid diagram of the mixture, but, as a first approximation, only the shape of the ME Iiquidus is modified Indeed as shown by the solubilit) cun es of the different isomers in the aromatic solution, considered to be ideal (Fig. 4.11), p-xylene is the compound that crystallizes first as the temperature is lowered... 

Figure 3.5. Data input for binary vapor-liquid diagram.

Figure 3.6. Ethanol-water vapor-liquid diagram for ideal thermodynamics.

Figure 6.7. Vapor-liquid diagram for acetone-water.

Construction of material balance lines on solid-liquid diagrams depends... 

We now describe the phase behavior exhibited by binary mixtures at modest pressures. The kinds of behavior observed in Nature include vapor-liquid equilibria (VLE, 9.3.1-9.3.3), azeotropes ( 9.3.4), critical points ( 9.3.5), liquid-liquid equilibria (LLE, 9.3.6), and vapor-liquid-liquid equilibria (VLLE, 9.3.7). When solid-fluid equilibria occur ( 9.4), many (but not all) of the resulting phase diagrams are analogous to their counterparts in fluid-fluid equilibria for example, many liquid-solid diagrams are analogous to vapor-liquid diagrams. 

Txy diagrams for vapor-liquid equilibria are equivalent to Txx diagrams for liquid-solid equilibria we merely relabel the lines and regions. When two structures are the same but have different labels, we say the structures are isomorphisms an example is shown in Figure 9.29. However, we caution that not all liquid-solid diagrams are isomorphic to vapor-liquid diagrams liquid-solid systems can also display phase behavior, such as peritectics, that rarely or never occurs in vapor-liquid systems. 

The assumption of equal molal overflow (acetone 7076 vs. water 9270 cal/mol) is not valid enough to use a standard vapour/liquid diagram for a McCabe-Thiele solution of acetone/water fractionation. Using corrected molecular weights as in Table 16.11 allows a graphical solution. 

Figure 3 Vapor-liquid diagram for a binary mixture of components P and O , illustrating the principles of distillation (see text for details).

The vapor-liquid diagram (Figure 3.3.6a) relates the composition of the vapor and the hquid phase for each boiling temperature. Thus we can deduce the vapor-hquid equflibrium plot (Figure 3.3.6b), which represents the molar fraction of benzene in the vapor phase (y) as a function of the molar content in the liquid mixture (x). This diagram can also be derived based on the relative volatility a, which is an... 

Design a distillation column to separate a mixture of ethanol and water into a water-rich stream (98 mol% water) and an ethanol-rich stream (80 mol% ethanol). The feed to the distillation colunm is a liquid-vapor mixture equilibrated such that Methanol = 0.443 and A ethanol = 0.10. Use the ethanol-water vapor-liquid diagram from Exercise 4.24 to determine... 

The curves given in Figs. 2-1 and 2-2 are termed the normal type. However, there are several other common types of curves. In Fig. 2-3 temperature-composition diagrams for constant total pressure are given for four different types of binary mixtures, and in Fig. 2-4 the corresponding vapor-liquid diagrams are given for the four same mixtures. 

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