J. C M . EW. Dei% 1991, 36, 137-140
accuracy, 5-lo%, given by Reid et ai. (72)for this conelatbn.
T,,T,
”‘
conciurlon
Qt 2
New binary diffusion coefficients for the halocarbons CC12F2 and C2C12F,, with H2, N2,and He, are presented together with the corresponding temperature dependence coefficients in the 298-343 K region. The arrested-flow method is easy to implement with a reasonable accuracy using simple equipment. The discrepancy observed between experimental and predicted values shows the necessity of experimental measurements to obtain reliable data. binary diffusion coefficient, cm2/s axial diffusion coefficient, cm2/s experimental flow rate and flow rate corrected to column conditions, cm3/mln exponent of the temperaturedependent equation for Dm vapor pressure of water at ambient temperature, mm Hg spatial variance, m2 cross-sectionalarea of the chromatogaphii column,
m2 time period corresponding to the flow arrest time, s time period during convection of solute pulse to column midregion, s time period during convection of solute pulse out of the column, s
A
137
ambient and column temperature, K linear velocity of the carrier gas, cm/min standard deviation, s2 width at half-helght of a chromatographic peak,
s
Reglatry No. R12,75-71-8 R114,76-14-2; H,, 1333-74-0; N,, 772737-9;
He, 7440-59-7.
Literature Cited Fuller, E. N.; Ensky, K.; CaMn. J. G. J. phys. Chem. 1968, 73, 3679. Maynard, V. R.; Qrushka, E. In Advances in ctnwnntogephy; Glb dings, J. C.; Grushka, E., Kdler, R. A., Cazes, J., E&.; Ddtker: New York, 1975; Vol. XII, p 99. Choudhary, R. J . Clvomtop.. 1974. 98, 491. Ashraf, S. M.; Srivastava, R.; Hussaln, A. J . chem.Eng. Dam 1886, 31, 100. McCoy, D. J.; Moffat, A. J . Chem. €ng. Commun. 1986, 47, 219. Knox, J. H.; McLaren, L. Ana/. Chem. 1864, 36,1477. Katsenos, N. A.; Karaiskakls, 0. J . Chromatop.. 1989, 254, 15. Amowoux, J.; Sanchez, 8.; Saht Yrlex, A. Bul. Soc. Chh. Fr. 1978, 1 1 , 462. Katsanos, N. A.; Karalskakis, G.; Vattls, A.; LycoughloHs, A. Chromaroaephia 1881, 14, 695. Hlrschfelder,J. D.; C d s . C. F.; Bird, R. hMscu/t?rlheory of gases and Ilqulds; Wky: New York, 1964. Bottomley, 0.; Nalrn, D. 8. Aust. J . Chem 1977. 30, 1645. Reid, R. C.; Prausnitz, J. M.; SheFWood,T. K. Thepropertles ofgases and/iqu&is;McOlawHUI: New York, 1977; p 560. Glddlngs, J. C.; Seeger, S. L. J . chem.phys. 1960, 33, 1579, T. C.; 13. Yang, F. P.; Hang, C. H.; Kw, C. H. J . C / ” t o g r . Hung, 1972, 70,
Recelved for review July 20. 1969. Revised April 13, 1990. Accepted Octcber 29. 1990.
Vapor-Liquid Equilibrium for the 2-Propanol-Methyl Acetate-Dichloromethane System at 298.15 Kt In68 L. Acevedo, Graclela C. Pedrora, Eleuterlo L. Arancibia, and Mlguel Katz’ Citedva de Flslcoqdmica, Institute de Ingen& Qdmica, Facuttad de Cienclas Exactas y Tecnobgh, U.N. de Tucumh, A&. Independencle 7800, S.M. de Tucudn (4000), R. Argentina
Isothermal vapor-liquid equilibrium data were determined for the O-propaoi-methyi acetate-dkhbromethane system at 298.15 K, by udng a modified verdon of a BouMlk-Eonson stili. The data proved to be thermodynamlcaily consistent. Excess molar Gibbs energks Ge were calculated over the entlre range of composition. Mtferent expressions existing in the literature were used to predict Gc from the correspondlng Mnary data. The empMcal correlation of Clbuika resuited in being the best one for this system. Introduction Vapor-liquld equilibrium (VLE) data are necessary for the deslgn of distillation processes. No experimental data have been reported In the available literature for the ternary 2propanol methyl acetate dlchloromethane system at 298.15 K. I n previous papers we have published denstties and viscosities ( I ) , as well as molar excess Glbbs energies GEfor
+
+
tPresenied a? the XV J nadas sobre Investigaclh en ClenClaS de la Ingsnleria Quhr(ce y &lca Apllcada. Neuqh, Argentina, November 1989. 0021-9568/91/ 173&0137$02.50/0
the corresponding binary mixtures (2-4). From the experimental VLE data, for this ternary system, activity coefficients y,and GE can be calculated and compared with values predicted from different expressions in terms of the binary data (5-77).
Experlmental Section The methods used in our laboratory have already been described ( 7-4). Densities were determined with a digital densimeter AP, Model DMA 45. All weighings were made on an H315 Mettler balance. A thermostatically controlled bath (constant to 0.01 K) was used. Temperatures T were read from calibrated thermometers. Calibration was done with air and doubly distilled water. The accuracy in density p was 0.01 % . Equilibrium data, pressure P , and mole fractions x, In the liquid phase and y, in the vapor phase were determined by using a modified version of the still described by Boubllk and Benson (72). The still and a water ebulliometer were attached to a large vessel that could be maintained at the requked constant pressure. P was calculated from the boiling point of water in the ebulliometer. The later could be determined with an accuracy of 0.01 K with a Dlgitec digital thermometer. The t m perature in the still was also measured to 0.01 K with a call@ 1991 American Chemical Society
138 Journal of chemical and Engb~wlngData, Vol. 36,No. 2, 1997
Table I. Densities pi and Vapor Pressure Pi of Pure Components at 298.16 K ~ ~ / ( lkg 0 -m-3) ~ PJkPa compound this work lit. this work lit. 5.81 (18) 0.7807 (17) 5.81 2-propanol (1) 0.7800 methyl acetate (2) 0.9272 0.9274 (19) 28.86 28.86 (19) dichloromethane 1.3151 1.3168 (19) 57.85 58.29 (20) (3)
In y I =
brated thermometer. The analysis of the liquid and condensed vapor were carrled out by using a Perkh Elmer-type Sigma 300 gas chromatograph, equipped with a thermal conductivity detector. The current suppUed to the detector was 150 mA. The copper column was 180 cm long, supplied readypacked with 1.5% Carbowax 20M over graphitized carbon black 70/100. The Injector and detector temperatures were 120 and 150 O C , respectively. Hydrogen was used as the carrier gas. Calibration analyses were carried out with 15 samples of known compositions, three injections for each sample were made, and an LC1-100 integrator was used to calculate areas. The sam pie concentratlons were accurate to better than 0.5 mol %. The materials used for the experiments were purified as described previously (7-4). Mixtwes were prepared by mixing weighted amounts of the pure liquids. Caution was taken to prevent evaporation.
The values of the molar virial coefficients B#of the pure components and the cross virial coefficients for the binary mixtures are as follows: B,, = -2408 X 10" m3 mor'; B, = -1626 X lo-' m3mol-'; BS = -862 X 10" m3 mor'; B,, = -2381 X 10" m3 mol-'; B13 = -1638 X 10" m3 mor1; 6, = -1239 X 10" m3 mol-'. These values were estimated from the Hayden and O'Connell method (74). The molar volumes V, were calculated from the densities p, (Table I). The ternary data reported in Table I1 were found to be thermodynamically consistent, as tested by the McDermot-Ellis method (75), following Wisniak and Tamir (76). Two experimental points are considered thermodynamically consistent if the following condition are fullfilled:
where
D
