Ethanol with Benzene and Water (IUPAC SDS Volume 69)
Evaluator
Adam Skrzecz Institute of Physical Chemistry, Polish Academy of Sciences
Evaluation
A survey of reported compositions along the saturation curve and compositions of coexisting phases in equilibrium (eq.) and distribution of ethanol between phases (distr.) for the system ethanol-benzene-water is given in Table 17.

Saturation curve

The ternary system ethanol-benzene-water forms a miscibility gap of type 1. Data for the system were reported in 23 references over the temperature range 263-342 K. The system is evaluated on the basis of the original papers. Only one binary system, benzene-water, is partially miscible. The data for this system were compiled and critically evaluated in a previously published SDS volume, Ref. 24. These recommended values of mutual solubility at 293 K are x'2=0.00975; x"2=0.000 406; at 298 K- x'2=0.9970, x"2=0.000 409 and at 333 K-x'2=0.991 04, x"2=0.000 534. Only the paper of Barbaudy, Ref. 9 at 333.2 K reported mutual solubility of the binary system: x'2=0.9893 and x"2=0.0005. This is in agreement with the recommended values, Ref. 24. The results of Taylor,1 Lincon,2 Perrakis,7 Tarasenkov and Polozhentseva,13 and Letcher et al.23 aare not reported as compilation tables. The data of Taylor1 and Lincon2 at 298.2 K published at 1896 and 1899 were reported as volume ratios. These data were recalculated to mole fractions, and they were taken into account for this evaluation; they are in agreement with other data sets at the same temperature. Data of Perrakis7 at 294 K present a significantly larger miscibility gap than any other data at 293 K and therefore these data are rejected as are other alcohol-benzene-water systems presented in Ref. 7. Data of Tarsenkov and Polozhentseva13 were obtained for this evaluation from Tarasenkov and Paulsen.25 These data present a much smaller miscibility gap (at maximum ethanol concentration of about 0.03 mole fraction of C2H5OH) which is inconsistent with all other experimental data and an unreasonable large solubility of waer in benzene (solubility of benzene in water estimated on the basis of these data seems to reach value x"2=0.94). Therefore, this data set is rejected. All experimental data of Letcher et al.23 were presented in the paper in graphical form only and therefore were not compiled. The miscibility gap decreased with the increasing temperature. This behavior is observed in all studies at more than one temperature.5,6,9,17,19,22 Data reported by Brandani et al.22 show a slightly smaller miscibility gap than other data at 303.2 K (Wehmann, Ref. 6 and Sata and Kimura, Ref. 14) and at 313.2 K (Morachevskii and Belousov, Ref. 19). The reported data are consistent within each data set and for each study. All data on the saturation curve are treated as tentative. Characteristic points on the binodal curve at selected temperatures, reported or estimated for plait points and for maximum ethanol concentration, are presented in Table 18. At the point of maximum ethanol concentration the errors estimated by the evaluator are 0.005 and 0.015 mole fraction for ethanol and benzene, respectively.
The temperature of 298.2 K, a standard temperature in which various alcohol-hydrocarbon-water systems are presented, was chosen to present the behavior of the system. Saturation and equilibrium data of Refs. 1, 2, 5, 8, 9, 15, 16, and 18, water-rich and hydrocarbon-rich branches were descrbed together by the equation:
x1=0.541 21+0.062 76 ln(x2)-0.083 61x2-0.468 57x22.
The least-squares method was used and the standard error estimate was 0.0106. The proposed equation is not appropriate for the binodal curve at >0.98 mole fraction of benzene. The compositions on the saturation curve calculated by the proposed equation are presented in Table 19 for selected concentrations of benzene in the mixture. The results of the calculations (solid line) are also presented graphically in Figure 10 together with selected experimental data, Refs. 5, 8, 9, 15, 16, 18, reported at 298.2 K.

Phases in equilibrium
Compositions of coexisting phases in equilibrium for the ternary system ethanol-benzene-water were reported in 11 references over the temperature range 293-342 K as 20 data sets (mainly isotherms). The tie lines cover the full area of miscibility gap. Reported data are consistent within each data set. Only data of Tarasenkov and Polozhentseva13 were rejected; these tie lines were inconsistent with all others. Vapor-liquid-liquid equilibria or boiling points of two-phase mixtures are reported in the papers of Barbaudy11 at 101 kPa and of Morachevskii and Belousov19 at temperatures 308.2, 318.2, 328.2, and 337.2 K. These data sets are consistent with other equilibrium data at lower temperatures. Changes of tie line direction are observed with temperature. With increasing temperature the water concentration in benzene-poor phase decreases for similar composition of benzene-rich phase; at temperatures over 333 K the concentration (in mole fraction) of ethanol in both phases in equilibrium reaches nearly the same values. This may be observed in data sets reported in Refs. 9, 11, 19, and 22. The equilibrium compositions of both phases of Ross and Patterson at 293.2 K21 (referring also to density and surface tension of phases in equilibrium), are identical with those of Morachevskii and Belousov.19 The reported experimental plait points are presented in Table 17. All equilibrium data are treated as tentative. Selected experimental points at 298.2 K, both saturation and equilibrium data, are presented in Figure 10 .
TABLE 18. Characteristic points on the binodal curve of the system ethanol-benzene-water
C $T$ ($\pu{K}$) D $x_{1}$ D $x_{2}$
288.2 4.38 x 10-1 1.98 x 10-1
288.2 3.89 x 10-1 4.13 x 10-1
293.2 4.35 x 10-1 1.95 x 10-1
293.2 - - -
298.2 4.18 x 10-1 2.11 x 10-1
298.2 3.91 x 10-1 3.18 x 10-1
298.2 4.16 x 10-1 1.81 x 10-1
298.2 3.93 x 10-1 3.22 x 10-1
298.2 4.19 x 10-1 2.44 x 10-1
298.2 3.98 x 10-1 3.25 x 10-1
298.2 4.0 x 10-1 2.0 x 10-1
298.2 3.8 x 10-1 3.7 x 10-1
299.2 4.25 x 10-1 2.62 x 10-1
299.2 3.95 x 10-1 3.43 x 10-1
303.2 3.85 x 10-1 1.54 x 10-1
303.2 3.65 x 10-1 3.53 x 10-1
303.2 4.12 x 10-1 2.26 x 10-1
303.2 - - -
313.2 3.84 x 10-1 1.98 x 10-1
313.2 3.44 x 10-1 3.30 x 10-1
328.2 3.54 x 10-1 2.71 x 10-1
328.2 3.54 x 10-1 2.71 x 10-1
338.2 3.44 x 10-1 2.12 x 10-1
338.2 3.44 x 10-1 2.12 x 10-1

TABLE 19. Calculated compositions along the saturation curve at 298.2 K
C $T$ ($\pu{K}$) D $x_{1}$ D $x_{2}$
298.2 0.0 4.09 x 10-4
298.2 1.076 x 10-1 1.0 x 10-3
298.2 2.513 x 10-1 1.00 x 10-2
298.2 2.938 x 10-1 2.00 x 10-2
298.2 3.351 x 10-1 4.00 x 10-2
298.2 3.579 x 10-1 6.00 x 10-2
298.2 3.730 x 10-1 8.00 x 10-2
298.2 3.837 x 10-1 1.000 x 10-1
298.2 3.914 x 10-1 1.200 x 10-1
298.2 3.969 x 10-1 1.400 x 10-1
298.2 4.008 x 10-1 1.600 x 10-1
298.2 4.034 x 10-1 1.800 x 10-1
298.2 4.047 x 10-1 2.000 x 10-1
298.2 4.051 x 10-1 2.200 x 10-1
298.2 4.046 x 10-1 2.400 x 10-1
298.2 4.033 x 10-1 2.600 x 10-1
298.2 4.012 x 10-1 2.800 x 10-1
298.2 3.984 x 10-1 3.000 x 10-1
298.2 3.950 x 10-1 3.200 x 10-1
298.2 3.909 x 10-1 3.400 x 10-1
298.2 3.863 x 10-1 3.600 x 10-1
298.2 3.811 x 10-1 3.800 x 10-1
298.2 3.753 x 10-1 4.000 x 10-1
298.2 3.690 x 10-1 4.200 x 10-1
298.2 3.622 x 10-1 4.400 x 10-1
298.2 3.549 x 10-1 4.600 x 10-1
298.2 3.471 x 10-1 4.800 x 10-1
298.2 3.388 x 10-1 5.000 x 10-1
298.2 3.300 x 10-1 5.200 x 10-1
298.2 3.208 x 10-1 5.400 x 10-1
298.2 3.111 x 10-1 5.600 x 10-1
298.2 3.009 x 10-1 5.800 x 10-1
298.2 2.903 x 10-1 6.000 x 10-1
298.2 2.793 x 10-1 6.200 x 10-1
298.2 2.678 x 10-1 6.400 x 10-1
298.2 2.558 x 10-1 6.600 x 10-1
298.2 2.435 x 10-1 6.800 x 10-1
298.2 2.307 x 10-1 7.000 x 10-1
298.2 2.175 x 10-1 7.200 x 10-1
298.2 2.039 x 10-1 7.400 x 10-1
298.2 1.898 x 10-1 7.600 x 10-1
298.2 1.753 x 10-1 7.800 x 10-1
298.2 1.604 x 10-1 8.000 x 10-1
298.2 1.451 x 10-1 8.200 x 10-1
298.2 1.294 x 10-1 8.400 x 10-1
298.2 1.133 x 10-1 8.600 x 10-1
298.2 9.67 x 10-2 8.800 x 10-1
298.2 7.98 x 10-2 9.000 x 10-1
298.2 6.25 x 10-2 9.200 x 10-1
298.2 4.47 x 10-2 9.400 x 10-1
298.2 2.65 x 10-2 9.600 x 10-1
298.2 8.0 x 10-3 9.800 x 10-1
298.2 0.0 9.970 x 10-1

Figure
Solubility graph
Sources:

1 Taylor, S. F.; J. Phys. Chem. 1, 461 (1897).
3 Bonner, W. D.; J. Phys. Chem. 14, 738 (1909).
5 Sidgwick, N. V.; Spurrell, W. J.; J. Chem. Soc. 117, 1397 (1920).
8 Barbaudy, J.; C. R. Hebd. Seances Acad. Sci. 182, 1279 (1926).
15 Varteressian, K. A.; Fenske, M. R.; Ind. Eng. Chem. 28, 928 (1936).
17 Staveley, L. A. K.; Johns, R. G. S.; Moore, B. C.; J. Chem. Soc. 1951, 2516-23.
18 Chang, Y. C.; Moulton, R. W.; Ind. Eng. Chem. 45, 2350 (1953).
19 Morachevski, A. G.; Belousov, V. P.; Vestn. Leningr. Univ.; Ser. 4: Fiz.; 4, 117 (1958).
2 Lincoln, A. T.; J. Phys. Chem. 4, 161 (1899).
13 Tarasenkov, D. N.; Polozhentseva, E. N.; Zh. Obshch. Khim. 2, 84 (1932).
12 Washburn, E. R.; Hnizda, V.; Vold, R.; J. Am. Chem. Soc. 53, 3237 (1931).
6 Wehrmann, F.; Z. Elektrochem. 27, 379 (1921).
11 Barbaudy, J.; J. Chim. Phys. 1927, 24, 1.
20 Mertslin, R. V.; Nikurashina, N. I.; Kamaevskaya, L. A.; Zh. Fiz. Khim. 35, 2628 (1961).
21 Ross, S.; Patterson, R. E.; J. Chem. Eng. Data. 24, 111 (1979).
22 Brandani, V.; Chianese, A.; Rossi, M.; J. Chem. Eng. Data 30, 27 (1985).
23 Letcher, T. M.; Sewry, J.; Radloff, S.; S. Afr. J. Chem. 43, 56 (1990).
24 Shaw, D. G.; 'Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7' IUPAC Solubility Data Series, 1989, Vol. 37, Pergamon Press.
25 Tarasenkov, D. N.; Paulsen, I. A.; Acta Physicochim. URSS 11, 75 (1939).
9 Barbaudy, J.; Recl. Trav. Chim. Pays-Bas 45, 207 (1926).
4 Holmes, J.; J. Chem. Soc. 113, 263 (1918).
7 Perrakis, N.; J. Chim. Phys. 22, 280 (1925).
10 Wright, R.; J. Chem. Soc. 129, 1203 (1926).
14 Sata, N.; Kimura, O.; Bull. Chem. Soc. Jpn. 10, 409-20 (1935).