THE PHYSICAL PROPERTIES OF THE TERNARY SYSTEM ETHYL ALCOHOL-GLYCERIN-WATER1 R. C. ERNST, C. H. WATKINS, AND H. H. RUWE Chemical Engineering Laboratories, University of Louisville, Louisville, Kentucky Received January 2, 1936 INTRODUCTION
This and a previous investigation (10) were undertaken to obtain data to be used in the study of distillation of ternary mixtures. The densities, surface tensions, viscosities, refractive indices, and specific heats for the ternary system ethyl alcohol-glycerin-water are reported in this paper. A later paper will contain latent heats, boiling points, vapor pressures, and liquid-vapor composition data for the two ternary systems. Densities (4),specific heats (13), refractive indices (ll), and viscosities (19) of the binary system glycerin-water have been determined previously by various experimenters. The binary system ethyl alcohol-water has been investigated by Bose (6), who determined specific heats, and by Winkler (22) for density. This investigation includes the determination of densities, surface tensions, viscosities, refractive indices, and specific heats of the ternary system ethyl alcohol-glycerin-water. EXPERIMENTAL
Materials. Glycerin of the C.P. grade was purified by repeated distillation under reduced pressure. C.P. ethyl alcohol was treated successively with metallic calcium, sodium hydroxide, and finally with metallic sodium, and distilled after each addition. The water was treated with potassium permanganate and distilled ; then treated with barium hydroxide and distilled repeatedly. The physical constants of the purified materials are given in table 1. Preparation of samples. The samples were prepared on a weight per cent basis in increments of 10 per cent. The composition of these samples is shown in table 2. Apparatus. Densities were determined by using a Geissler pycnometer. An Ostwald-Poiseuille viscosimeter (23) was employed for the determination of viscosities. The surface tension was measured by means of the 1 Presented before the Division of Physical and Inorganio Chemistry at the Mid-West Regional Meeting of the American Chemical Society, October 31 to November 2, 1935.
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rise in a capillary tube (21). An Abbe refractometer (1) was used in obtaining refractive indices. Specific heats (17) were determined by introducing a measured quantity of electricity into the liquid and recording the temperature rise. ii portable watt-second meter (Sangamo Electric Co.) and a thermometer with 0.1" graduations were used to determine these values. A carbon resistor was used as a heating element. This apparatus was inclosed in a silver-plated glass tube surrounded by an evacuated jacket. TABLE 1
Physical constants o j purijed materials MATERIAL
DENSITY
I
VISCOSITY
SURFACE TENSION
1
REFRACTIVE INDEX
SPECIFIC H E A T
Ethyl alcohol
0.7851* 0.78506 (14)t 0.78510 (22)
1.10+ 1.101 (9)
22.0* 22.03 (3)
1.3596* 1.35941 (2)
0.536* 0.54 (16)
Glycerin
1,2580* 1.2580 (4) 1,25802 (5)
934* 945 (19)
62.5* 63.0 (8)
1.4729* 1.4730 (11)
0.555*
0.99707 0.99707 (20) 0.99707 (7)
0,893 0.894 (12) 0.893 (18)
72'0 72.0 (16)
1.3332* 1.3325 (15) 1.3333 (10)
1.oo
Water
* Author's
1
0.541 (13) 0.589 (13)
experimental values.
t The numbers in parentheses refer t o the bibliography. DISCUSSION
Theresultsof theexperimentalworkareshownin table 3. From the data obtained, both binoidal and triangular diagrams have been drawn for each physical property. The binoidal curves are plotted with the composition of the sample on the abscksa versus the particular property under consideration as the ordinate. The constant property lines on the triangular diagrams were prepared from the binoidal curves. Relative density. Figure 1 is a binoidal graph of the relative densities against composition. The line representing the densities of the ethyl alcohol-water system curves upward, indicating a decrease in volume upon mixing. These values agree with those of Winkler (22). The densities of the ethyl alcohol-glycerin system lie between the values €or alcohol and glycerin, but likewise show a decrease in volume upon mixing. The water-glycerin curve slopes downward, denoting a slight increase in volume when mixed, agreeing with Bosart and Snoddy (4). The constant per cent glycerin curves and the constant per cent ethyl alcohol curves show a curvature similar to the ethyl alcohol-water and the
TERNARY SYSTEM ETHYL ALCOHOL-GLYCERIN-WATER
629
glycerin-water curves, respectively. The characteristic curvature of the lines on the triangular diagram (figure 2) is to be expected because of the change in volume when the different components are mixed.
TABLE 2 Composition of the samples SAMPLE NUMBER
WEIGHT
PER CENT 3LYCERlN
,EIGHT PEE DNT ETHYL ALCOHOL
HEIGHT PER ENT WATER
SAMPLE NUMBER
WEIGHT PER CENT GLYCERIN
VEIQHT PEE ENT ETHYI ALCOHOL
50 40 30 20 10 70 60
10 10
WEIGHT PER CBNT WATER
~~
1 2 3 4 5 6 7 8 9
100
100 10 20 30 40 50 60
10
70
11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
80 90
100 90 80
70 60 50 40 30 20 10
90
10
80
20 30 40 50 60 70 80 90
70 60 50 40 30 20 10
10 20 30 40 50
60 70 80 90 80
70 60
90 80 70 60 50 40 30 20 10 10 10 10
10 20 30
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 E4
55 56 57 58 59 60 61 62 63 64 65 66
50
40 30 20 10 60 50 40 30 20 10 50 40 30 20 10 40 30 20 10 30 20 10 20 10 10
10
10 10 20 20 20 20 20 20 20 30 30 30 30 30 30 40 40 40 40 40 50 50 50 50
60 60 60 70 70 80
40 50 60 70 80 10 20 30 40 50 60 70 10
20 30 40 50 60 10
20 30 40 50 10 20 30 40 10
20 30 10 20 10
Surface tension. The curve (figure 3) representing the binary system ethyl alcohol-glycerin is smooth but rises abruptly from the 80 per cent glycerin composition. The constant per cent water lines have the same characteristic curvature. The surface tensions of the water-glycerin mixtures are between the
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TABLE 3 Physical properties SAMPLE NUMBE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
DENSITY
YISCOSITY
0.7851 1 .2627 1.oooo 0.9833 0.9692 0.9535 0.9342 0.9125 0.8895 0.8659 0.8415 0.8160 1.2356 1,2089 1,1819 1,1545 1.1272 1.1003 1.0738 1 0484 1.0237 0.8199 0.8566 0.8947 0.9368 0.9806 1.0288 1,0797 1.1366 1.1932 1,1724 1.1484 1.1212 1.IO04 1.0776 1.0514 1,0270 1.0025 1.1165 1.0988 1,0753 1.0525 1.0318 1.0101 0.9882 1.0618
1.10 934.0 0.893 1.33 1.76 2.13 2.34 2.33 2.24 2.04 1.72 1.41 155.6 55.8 18.5 9.38 5.34 3.18 2.14 1.54 1.09 1.52 2.23 3.49 5.83 10.4 20.6 45.3 103.3 254.0 74.6 26.2 14.1 7.42 4.75 3.13 2.22 1.69 41.1 16.9 9.29 5.91 4.04 2.92 2.20 19.50
SURFACE TENSION
REFRACTIVE INDEX
22.0 62.5 72.0 46.6 37.7 32.3 29.6 28.3 26.9 26.1 25.2 24.4 64.5 65.7 66.5 66.9 67.4 67.9 68.5 69.5 70.5 22.9 23.9 24.2 25.4 26.1 27.7 29.6 32.7 38.9 40.4 39.9 40.4 41.3 42.7
1.3596 1.4729 1,3332 1,3399 1,3453 1.3510 1,3552 1,3587 1.3610 1.3628 1.3630 1,3624 1,3472 1.4435 1.4281 1.4145 1.3992 1.3858 1.3708 1.3582 1,3451 1,3701 1.3799 1,3898 1.4005 1.4109 1.4226 1.4344 1,4470 1,4597 1,4462 1.4321 1.4193 1.4063 1.3917 1,3769 1,3639 1.3511 1.4343 1.4220 1.4096 1.3961 1,3827 1.3705 1.3573 1.4235
44.0 45.4 46.4 32.7 33.5 34.6 34.9 35.1 35.9 37.0 30.4
SPECIFIC HEAT
0.537 0.555 1.Ooo 1.036 1.040 0.995 0.964 0.915 0.859 0.784 0.700 0.618 0,579 0.610 0.665 0.715 0.770 0.810 0,870 0.930 0.967 0.550 0.550 0.549 0.548 0.550 0.549 0.549 0.551 0.552
0.581 0.622 0.675 0.741 0.790 0.856 0.921 0.966 0.588 0.635 0.681 0.735 0.810 0.885 0.953 0.591
63 1
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TABLE 3-Concluded SAMPLE N U Y B E U
47 48 49 50
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
1
DENSITY
1.0460 1 ,0273 1.oO90 0.9888 0.9690 1.0149 0.9984 0.9821 0.9655 0.9486 0.9670 0.9553 0.9430 0.9272 0.9282 0.9143 0.9016 0.8889 0.8796 0,8505
1
VIBCOSITY
10.80 6.63 4.60 3.47 2.69 12.3 7.04 4.73 3.57 2.84 6.63 4.59 3.52 2.78 4.26 3.26 2.59 2.88 2.36 2.00
SURFACE TBNSION
30.1 31.3 31.6 32.0 32.8 28.8 28.9 28.9 29.6 29.9 27.2 28.0
27.5 28.3 26.3 26.3 27.0 24.5 25.6 24.6
REFRACTIVE INDEX
SPECIFIC EDAT
1.4112 1.3990 1.3871 1.3749 1.3631 1.4120 1.4006 1.3900 1.3787 1.3672 1.4011 1.3907 1 .3810 1.3700 1.3911 1.3817 1.3717 1.3812 1 ,3721 1.3720
AQLYCLRINE
WElOHT PERCENT WATER
FIQ.1 FIQ.2 FIQ.1. Relative density glycerin-ethyl alcohol-water a t 25°C. FIG.2. Relative density glycerin-ethyl alcohol-water a t 25'C'
0.644 0.690 0.754 0.831 0.910 0.592 0.642 0.702 0.775 0.860 0.591 0.648 0.720 0.809 0.582 0.660 0.741 0.610 0.677 0.616
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R. C . ERNST, C . H. WATKINS, AND H. H. RUWE
68
t 60 /XOLYCERINE
0:
2 52 u)
Y
E
44
13s w
2 28
f
20' 100
I I I i 80 60 40 20 0 WEIGHT PERCENT GLYCERINE
WATER
ETHYL ALCOHOL
FIQ.3 FIQ.4 FIG.3. Surface tension glycerin-ethyl alcohol-water a t 25°C. FIG.4. Surface tension glycerin-ethyl alcohol-water a t 25°C.
WEIGHT PERCENT ETHYL ALCOHOL
WATER
ETHYL ALCOHOL
FIG.5 FIQ.6 FIG,5. Refractive index glycerin-ethyl alcohol-water a t 25'C. FIG.6. Refractive index glycerin-ethyl alcohol-water a t 25°C.
TERNARY SYSTEM ETHYL ALCOHOL-GLYCERIN-WATER
633
A
OLYCERINE
WEIQHT
PERCENT
E T W L ALCOHOL
WATER
ETHYL ALCOHOL
FIQ.7 FIQ.8 FIG.7. Viscosity glycerin-ethyl alcohol-water a t 25'C. FIG.8. Viscosity glycerin-ethyl alcohol-water at 25'C.
FIQ.9 FIG.10 FIQ.9. Specific heat glycerin-ethyl alcohol-water a t 2 5 T . FIG.10. Specific heat glycerin-ethyl alcohol-water at 25°C.
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R . C. ERKST, C. H. WATKINS, AND H. H. RUWE
values for the pure components; they lie on a smooth curve but not in a straight line. In figure 4 the line representing compositions having a surface tension of 34.0 is a straight line. The lines on either side are convex with respect to this constant property line. Refractive indez. The refractive indices are shown graphically in figure 5 and figure 6. The values of the alcohol-water mixtures lie on a smooth curve reaching a maximum a t 80 per cent alcohol. The constant per cent glycerin lines show similar maximum points. The glycerin-water values curve slightly but are intermediate between the refractive indices of the pure components. The constant per cent water lines have the same curvature as the glycerin-alcohol curve. The constant property lines in figure 6 show a similar curvature throughout. Viscosity. Because of the high viscosity of glycerin, namely 945 centipoises (19), when compared to that of alcohol and water, the curves showing viscosities include only those samples whose glycerin percentages are below 40 per cent. I n figure 7 the alcohol-water mixtures have maximum viscosity at 50 per cent alcohol. The constant per cent glycerin curves show similar maximum points. These maxima explain the shape of the lines in figure 8. Specific heat. Figure 9 shows the specific heat of the system plotted against composition. The specific heat of the water-alcohol system reaches a maximum at 80 per cent water and drops on a smooth curve to pure alcohol. The glycerin-alcohol line is almost straight. The constant per cent glycerin lines show similar curvature, but approach straight lines a t 60 per cent glycerin. The slopes of the lines on the ternary diagram (figure 10) are explained by the constant per cent glycerin lines reaching a maximum. CONCLUSION
Densities, surface tensions, viscosities, refractive indices, and specific heats for the ternary system glycerin-ethyl alcohol-water have been determined. Both binoidal curves and ternary diagrams have been prepared for each property and are included in this paper. REFERESCES
(1) A B B ~E.: , Cads Repertarium der Physik 15, 643 (1879). (2) ANDREWS:J. Am. Chem. Sac. 30,353 (1905). (3) BIRCUMSHAW: J. Chem. Sac. 121, 887 (1922). (4) BOSART AND SNODDY: Ind. Eng. Chem. 19, 506 (1927). (5) BOSARTAND SNODDY: Ind. Eng. Chem. 20, 1377 (1928). (6) BOSE:Z. physik. Chem. 58, 585 (1907). (7) CHAPPIUS:Travaux et memoirs du bureau international des poids e t memure8 13: D 40 (1907).
TERNARY SYSTEM ETHYL ALCOHOL-QLYCERIN-WATER
635
(8) DRUCKER: 2. physik. Chem., Stoiohiometrie und Verwandtschaftslehre 62, 041 (1905). (9) DUNSTAN AND THALE: J. Chem. Soo. 96, 1556 (1909). ' (10) ERNST,LITKENHOUS, AND SPANYER: J. Phys. Chem. 36,842 (1932). (11) IYERAND USHER:J. Chem. Soo. 127,841 (1925). (12) JAYNER:J. Chem. SOC.121, 1511 (1922). (13) MAGIE:Phys. Rev. 16, 381 (1903). (14) OSBORNE, MCKELYY, AND BEARCE: Bur. Standards Bull. 9, 327 (1913). Ann. Physik 44,774 (1891). (15) QUINCKE: AND CARVER: J. Am. Chem. SOC. 43, 827 (1921). (16) RICHARDS AND GUCKER: J. Am. Chem. Soo. 47, 1876 (1925). (17) RICHARDS Ind. Eng. Chem. 24, 1061 (1932). (18) SHEELY: (19) SHEELY:Ind. Eng. Chem. 24, 1063 (1932). (20) THEISSEN, SCHEEL, AND DIESSELHORBT: Wiss. Abhandl. physik. tech. Reichsanstalt 2, 68 (1900). (21) Trans. Chem. SOC.63, 1089 (1873). Ber. S8, 3612 (1905). (22) WINKLER: (23) Wiss. Abhandl. physik. tech. Reiohsanstalt 4,241 (1901).
