Equilibrios de fase de vapor-líquido: constantes y coeficientes de actividad, Apuntes de Desarrollo Humano

¡Descarga Equilibrios de fase de vapor-líquido: constantes y coeficientes de actividad y más Apuntes en PDF de Desarrollo Humano solo en Docsity! 13-20 DISTILLATION Tam 1 + > a o Experimental data for toluene and n- heptane, respectively Regular solution theory — Regular solution theory with Flory- Huggins correction Liquid-phase activity cocfficient 0 0.2 0.4 06 0.8 1.0 Mole fraction of n-heptane FIG, 13-19 Liquid-phase activity cocfficients for an n-heptane- tem at 101.3 kPa (1 atm). [Henley and Seader, Equilib tage Separation Operations in Chemical Engineering, Wiley, New York, 1981; data of Yerazunis etal., Am. Inst. Chem, Eng. ol. 10, 860 (1964),) TABLE 13-2 Binary-Interaction Parameters* exceed values of approximately 7.5, the van Laar equation erro- neously predicts phase splitting; Tables 13-1, 13-2, and 13-4 include data on formic acid and acetic acid, two substances that tend to dimerize in the vapor phase accord- ing to the chemical-equilibrium expression Ko =Pp/Pi = 101=97 (13-5) where Kp is the chemical.equilibrium constant for dimerization, Po and Py are partial pressures of dimer and monomer respectively in torr, and Tis in K Values of A and B for the first four normal aliphiatic acids are A B Formic acid 10.743 3083 Acetic acid 10421 3166 n-Propionic acid 10.543 3316 n-Butyric acid -10.100 3040 As shown by Marek and Standart (Collect. Czech. Chem. Commun., 19, 1074 (1954)), itis preferable to correlate and utilizo liquid-phase activity cocfficients for the dimerizing component by considering sp: arately the partial pressures of the monomer and dimer. For example for a binary system of components 1 and 2, when only compound 1 dimerizes in the vapor phase, the following equations apply iFanideal gas is assumed: —Pp+ Py (13-6) ya (Pay + 2Pp)1P. (13-7) These equations when combined with Eq. (13-5) lead to the following equations for liquid-phase activity cocfficients in terms of measurable quantities: ” Py [ 14 (14 4KpP/99% -) 135) Pix LU + [1 + 4K0P (2 y] py (regla yl ) 13.9) Pétxo (2 — 1 + [1 + 4K Py r(2 131%) Detailed procedures, including computer programs for evaluating binary-interaction parameters from experimental data and then wtiliz- Margules van Laar n (cal/mol) System. Ay As As An (as — 2) Acetone (1), chloroform (2) 0.8404 0.5610 0.8643. 0.5899 116.1171 -506.8519 Acetone (1), methanol (2) 0.6184 0.5788 0.6184 0.5797 -114.4047 5452942 Acetone (1), water (2) 2.0400 1,5461 2.1041 344.3346 14822133 Carbon tetrachloride (1), benzene (2) 0.0948 0.0951 7.0459 59.6233 Chloroform (1), methanol (2) 0. 8320 0.9356 -361.7944 1694.0241 Ethanol (1), benzene (2) 1.8570 4.4318 2 118 Ethanol (1), water (2) 1.6798 953.2792 Ethyl acetate (1), ethanol (2) 0.8552 570.0439 n-Hexane (1), ethanol (2) 19398 1.9195 2189.2896 Methanol (1), benzene (2) 2.1411 2.1623 Methanol (1), ethyl acetate (2) 1.0016 1.0017 Methanol (1), water (2) 0.7923 0.5434 0.8041 0.5619 82.9876 Í5 Methyl acetate (1), methanol (2) 0.9605 2 0.9614 1.0126 -93.8900 2 A34S. 1-Propanol (1), water (2) 2.7070 2.9095 1.15 906.5256 1396.6398 2-Propanol (1), water (2) 2.3319 2.4702 1.0938 1230.2080 Tetralydrol ran (1), water (2) 2.8258 3.0216 1.9436 18447926 Water (1), acetic acid (2) 04178 0.4973 111.6579 Water (1), 1-butanol (2) 0.8608 1.0996 20502569 Water (1), formic acid (2) 0.2966 0.2715 0.2935 -310.1060 1180.5040 *Abstracted from Gmehling and Onken, Vapor-Liquid Equilibrium Data Collection, DECHEMA Chemistry Data ser, vol. 1 (parts 1-10), Frankfurt, 1977. Copyright O 1999 by The McGraw-Hill Companies, Inc. All rights reserved. Use of this product is subject to the terms of its license agreement. Click here to view.