ANALYTICAL CHEMISTRY
1204 the use of dibenaoylmethane for the colorimetric determination of uranium. All the salts were nitrates. Table I1 summarizes the results. LITERATURE CITED
(1) Crouthamel, C. E., and Johnson, C. E., ANAL.CHEM.,24, 1780 (1 952). (2) Dufraisse, C , and Gillet, A . , Ann. chim., 6,295 (1926). (3) Feigl, F., and Backer, E., Monatsh ,49,401(1928). (4)Furman, N.H., private communication, Aug. 4,1952. (5) Furman, N.H., Mundy, R. J., and Morrison, G. H., U. S. Atomic Energy Commission, Doc. 2861 (declassified June 21, 1950). (6) Job, P.,Ann. chim. (lo),9,113 (1928). (7) Kolthoff, I. M., and Lingane, J. J., J . Am. Chem. SOC.,55, 1871 (1933). (8) Muller, Chem-Ztg.,43,739 (1919).
(9) Rodden, C.J., editor, ”Analytical Chemistry of the Manhattan Project,” New York, McGraw-Hill Book Co ,1950. (10) Sandell, E. B., “Colorimetric Determination of Traces of Metals,” 2nd ed., New York, Interscience Publishers, 1950. (11) Scott, T.R.,Analyst, 74,486(1949). (12) Vosburgh, W. C., and Cooper, G. R., J . Am. Chem. SOC.,63, 437 (1941). (13) Ware, E., U. S. Atomic Energy Commission, Doc. MDDC1432 (declassifiedNov. 7,1947). (14) Yoe, J. H., rand Jones, A. L., IND. ENG.CHEW,ANAL.ED.,16, 111 (1944). (15) Zebroski, E.L., and Tolbert, B. M., U. S.Atomic Energy Commission, Doc. 1884 (declassified March 16,1948). RECEIVED for review March 27,1953. Accepted May 19,1953. Abstracted from a dissertation presented by Fritz Will, 111, to the Graduate Faculty of the University of Virginia in partial fulfillment of the requirements for the degree of doctor of philosophy, January 1953.
Ternary Methanol-Ethanol-Acetone and Three Related Binary Solutions Refractive Indices and Bubble Points H. H. AMER’
AND
R . R. PAXTON, Stanford University, Stanford, Calif.
MATTHEW VAN WINKLE, University of Texas, Austin, Tex. Refractive indices, n g , and bubble points at 760 mm. were determined for methanol-ethanol, acetone-ethanol, and acetone-methanol solutions and for 91 ternary methanol-ethanol-acetone solutions. A triangular analytical diagram hearing lines of constant refractive index and constant bubble point makes it possible to find the composition of any methanol-ethanol-acetone ternary solution for which the refractive index and bubble point are known.
HE purpose of this investigation was to obtain data useful ethanol, and T f o r analyzing ternary solutions of acetone, and also the three binary solutions of this system.
for variations in the atmospheric pressure from 760 mm. by means of a modified Clausius-ClaPeyron equation. The Corrections rarely exceed 0.3” C. The apparatus was occasionally checked using water. The bubble point of water waB
PURITY OF COMPONENTS
Table I compares the specific gravities, refractive indices, and bubble points of the components used in this investigation with those reported by earlier workers. The specific gravities were determined on samples maintained a t 25’ C. A Kestphal balance was used, and the uncertainty in the reported values is believed to be less than &0.0003 unit.
A precision Bausch & Lomb refractometer with a sodium D line light sourcc. was used to determine the refractive indices. Cooling water maintained a t 20.00” =t0.05’ C. was circulated around thp prisms of the refractometer. The refractive index readings were reproducible to &0.00002 unit and are believed accurate t o within &0.00005 unit. Most of the bubble points herein reported were obtained with a Cottrell ebulliometer similar to that described by Griswold, Sndres, and Klein ( 3 ) . The thermometer used was compared against a Bureau of Standards thermometer, The observed bubble points were corrected 1 Present Egypt.
address,
12
Talaat
St.,
Cairo,
: =
1.326
1.334
1.342 1.350 REFRACTIVE INDEX, ns’
1.358
1.366
Figure 1. Chart for Analysis of Acetone-Methanol and Methanol-Ethanol Solutions Mole fraction of acetone in acetone-methanol solutions, 33.62 (ma: - 1.32904) Mole fraction of methanol in methanol-ethanol solutions, 30.79 (1.36152 m
-
- &AM y) f
AME
V O L U M E 25, NO. 8, A U G U S T 1 9 5 3
1205
78
Table I.
74
9 70 J U
Properties of Pure Compounds Literature Values
Experimental Values
Coiiipound
Property
Methanol (h1.W. = 32.04)
Spec. gr., d:5 Ref. index, n22 Boiling pt., C.
0.7866 (6) 0.7865 1.3290 (6) 1.32904 64.65 ( 8 ) 64.6
Ethanol (M.W. = 46.07)
Spec. gr.. d:5 Ref. index, n2,0 Boiling pt., C.
0.78505 (2) 0.7850 1.36155 (2) 1.36152 78.27 ( 2 ) 78.3
Acetone (3I.W. = 58.08)
Spec. gr., d:5 Ref. index, n y Boiling pt., C.
0.78508 ( 2 ) 0.7840 1,35880 ( 2 ) 1.35878 56.20 (2) 56.1
366
G
Table 11. Refractive Indices of Binary Solutions of Sj-stem -Methanol-Ethanol-Acetone
w
a
5
62
I-
58
I
1
0 60
0 EO
54
0.20
0.40
1
I 00
IOLE FRACTION MORE VOLATILE COMPONENT Figure 2. Bubble Points of Methanol-Ethanol, Acetone-Ethanol, and Acetone-Methanol Solutions at 760-Mm. Pressure MethanolDetermined by Ethanol Cottrell ebulliometer 0 Equilibrium still e Griswold and Buford (4)
Acetone Ethanol
AcetoneMethanol
C
A 0
X
always found to be 100.00" i 0.10" C. corrected to 760 mni. of mercury. PROCEDURE AND RESULTS
At intervals as needed small batches of the components were purified by redistillation. The physical properties of the various batches always agreed with those cited in Table I within the ex-
ACETONE
90
Figure 3.
Methanol-Ethanol Mole fr. JIeOH n2D" 0 1.36152 1.38756 0.1378 1.35406 0.2644 1.35073 0.3813 0.4894 1 34750 1.34426 0.5898 1.34114 0 . 6832 1.33810 0.7704 1.33607 0.8519 1,33208 0.9283 1.32904 1.0000
Acetone-Methanol Jlole fr. acetone nz: 0 1,32904 1,33240 0.0678 0.1212 1.33600 1.33949 0.1912 0.2689 1 31280 1 34601 0 3555 1.34907 0.4528 1.35198 0.5628 1.35447 0.6881 0.8324 1 35672 1.35878 1.0000
Acetone-Ethanol Nole fr. acetone nz2 1.36152 0 1.36188 0.0810 1,36159 0 1655 1.36143 0.2537 1.36122 0.3459 1.36097 0.4423 1.36061 0.5434 1,36022 0.6492 1,35980 0.7604 1.38927 0.8771 1.0000 1.36878
perimental limits mentioned. Particular pains were observed in storing and mixing to keep the materials anhydrous. BINARY SOLUTIONS
Refractive Indices. Table I1 reports refractive indices of methanol-ethanol, acetone-methanol, and acetone-ethanol solutions. Inasmuch as these results are most likely to be of interest to those dealing with distillation and vapor-liquid equilibria, t h e concentrations are reported as mole fractions. These same data computed as mass fractions are available elsewhere (1). The consistency of these data can be tested by plotting refractive index against mole fraction. A more sensitive test of them can be made by plotting the deviation of the refractive indexconcentration curve from a straight line. Figure 1 is a curve of this type plotting A in mole fraction units against refractive index of the solution. The term A is defined by the following equaions: Bcetone-methanol.
Mole fr. acetone = 33.62 (n2,0 - 1.32904) - AAM Methanol-ethanol. Mole fr. methanol = 30.79 (1.36152 - nz;) -I-AMI
The refractive indices of acetone and ethanol are so close together that this method of analysis is not suitable for that solution. Bubble Points. Bubble points corrected to a pressure of 760 inm. are reported in Table 111 for methanol-ethanol, acetonemethanol, and acetone-ethanol solutions. For the first two solutions, data taken in a modified Colburn ( 7 )equilibrium still are also included. In this apparatus, the thermocouple used to measure bubble points was in a closed well 1 cm. below the surface of the boiling liquid. When the equilibrium still was used, the composition of the boiling liquid was determined by refractive index relations. The bubble point curves (Figure 2) indicate no measurable difference between these methods. Griswold and Buford ( 4 )have reported bubble point-composition data for acetone-methano1 solutions. Their acetone had a boiling point of 56.5' C., compared with 56.1' C. for the acetone used in this study. Their data were not used in Lines of Constant Refractive Index and Constant Bubble Point for Methanol-Ethanol-Acetone Solutions drawing the bubble point curve shown in Figure 2.
1206
ANALYTICAL CHEMISTRY
Table 111. Bubble Points at 760-Mm. Pressure of Binary Solutions of System Methanol-Ethanol-Acetone Methanol-Ethanol Acetone-Methanol Mole Bubble Mole Bubble frartion point, fraction point, O C. O C. acetone MeOH n 0 78.3 64.6 78.0 63.5 0.029 6.036a 77.4 62.8 0.058 0.084 76.6 62.2 0.081a 0.134'= 76.6 61.1 0.138 75.0 59.6 0.242" 74.6 59.4 0.264 73.6 58.4 0 . 320" 72.6 58.1 0.381 72.3 57.3 0.401" 71.7 56.9 0.435O 70.9 56.5 0.489 70.0 56.2 0.542" 69.4 56.0 0.590 68.6 55.9 0.652" 68.2 55.8 0.683 67.7 55.8 0.728" 67.1 55.8 0.770 66.9 55.8 0.790" 0.814n 66.6 55.8 0.852 66.1 55.8 55.8 0.873" 65.8 56.1 0.910' 65.6 0.928 65.3 64.6 1.OOO Determined in equilibrium still.
Acetone-Ethanol Mole Bubble fraction point, acetone C. 0 78.3 73.8 0.081 70.1 0.166 67.3 0.254 64.9 0,346 62.8 0,442 61.1 0.543 59.6 0,649 58.2 0.760 57.1 0,877 56.1 1.000
LITERATURE CITED
(1) Amer, H. H., Ph.D. thesis, Stanford University, 1952. (2) Dreisbach, R. R., and Martin, R. A,, Ind. Eng. Chem., 41, 2875
(1949). (3) Griswold, John, Andres, D., and Klein, V. A., Trans. Am. Inst. Chem. EngTs., 39, 237 (1943). (4) Griswold, John, and Buford, C. B., Ind. Eng. Chem., 41, 2347 (1949). ( 5 ) "International Critical Tables," Vol. 3, p. 27, New York, McGrawHill Book Co., 1928.
TERNARY SOLUTIONS
Measured amounts of the three compounds were carefully mixed. A portion of this mixture was set aside for refractive index measurements, and another portion was charged to the Cottrell bubble point apparatus. In all, 91 ternary mixtures were made up. The results are reported in Table IV. Table IV.
@)
'01*
7p
p.
( 7 ) Jones, C. A., Schoenborn, E. >I., and Colburn, A. P., Ind. Eng. C h m . , 35, 666 (1943). (8) Timmermans, J., and Hennault-Roland, J . chim. p h y s . , 27,
401 (1930). RECEIVED for re\-iew iMarch 16, 1953. .4ccepted May 25, 1953.
Analytical Data for Ternary Solution Methanol-Ethanol-.-icetone n' g 1.35924 1.35772 1.35620 1.35463 1.35293
Bubble point, a t 760 Xlm., C. 75.1 74.2 73.2 72.1 71.3
Refractive Composition, Mole Fraction Methanol Ethanol Acetone 0.070 0.891 0.039 0 139 0.823 0.038 0,205 0.758 0.037 0.267 0.696 0.037 0.637 0.036 0.327
These data, together with the binary data, were then plotted on a triangular diagram and lines of constant refractive index and constant bubble point were carefully drawn. Figure 3 shows that the lines of constant refractive index cross each line of constant bubble point once. Thus there is only one solution concentration that will satisfy a given refractive index and a given bubble point reading. As the lines cross a t nearly right angles all over the plot, their intersection is well defined, and the concentration of the solution is determined with a relatively high degree of precision. Bubble point determinations rather than refractive indices were the limiting factor in constructing this analytical diagram. It is believed that this diagram when used with the true bubble point and refractive index will permit the determination of the concentration of the three components within 0.005 mole fraction unit.
Index,
Composition, Mole Fraction Methanol Ethanol Acetone 0.713 0 124 0.163 0.081 0.160 0,759 0.040 0.157 0.803 0.076 0.633 0.292 0.148 0.566 0.286
Refractive Index, n go 1.34243 1.34102 1,33939 1.38949 1.35817
a t 7fO Mm., C. 61.6 61.1 60.7 65.5 64.8
0.385 0.441 0 495 0 545 0.595
0.580 0.525 0.471 0.421 0.372
0.035 0.034 0.034 0.034 0.033
1.35154 1.34969 1.34805 1.34643 1.34486
70.6 69.9 69.2 68.6 68.0
0.217 0.284 0.347 0.408 0.466
0.504 0.443 0.386 0 330 0.278
0.279 0.273 0.267 0.262 0.256
1.38671 1.35514 1.38362 1.35205 1.35064
64.0 63 4 62 8 62 2 61 6
0 643 0.689 0 734 0.777 0.818
0.326 0.280 0.236 0.193 0.152
0,032 0.031 0.031 0.030 0.030
1.34328 1.34143 1.33996 1.33854 1,33713
67.4 66.8 66.3 65 8 65.3
0.522 0.576 0.627 0.678 0.726
0.227 0.178 0.131 0.086 0.042
0.251 0.246 0.242 0.236 0.232
1.34998 (?) 1.34751 1.34602 1.34451 1.34287
61.1 60.6 60.2 59 8 59 4
0.858 0.898 0 935 0,073 0.142
0.112 0.073 0.036 0,808 0.741
0.030 0.029 0,029 0.120 0.117
1,33568 1.33399 1.33228 1.35949 1.35800
64.7 64.4 64.1 71.2 70.3
0,209 0.273 0.334 0.392 0.449
0.677 0.615 0.556 0.500 0.446
0.114 0.112 0.110 0.108 0.105
1.35659 1.35490 1.35331 1.35166 1.35014
69.6 69.0 68.2 67.5 66.9
0.503 0.566 0.606 0.654 0.701
0.393 0.343 0.295 0.248 0.203
0.104 0.101 0.099 0.098 0.096
1.34847 1.34713 1.34540 1.34385 1.34227
66.2 65.4 65.0 64.5 64.0
0.746 0.790 0.832 0.872 0.074
0.160 0.118 0.077 0.038 0.722
0.094 0.092 0.091 0.090 0.204
1,34073 1.33906 1.33745 1.33583 1.35968
63.5 63.0 62.6 62.2 68.1
0.145 0.213 0.278 0.340 0.400
0.656 0.592 0.531 0.473 0.417
0.199 0.195 0.191 0.187 0.183
1.35814 1.35662 1.35495 1.35366 1.35201
67.3 66.7 66.0 65.4 64.6
0.539 0.474 0.411 0.352 0.296 0.241 0.189 0.139 0,090 0.044 0.441 0,377 0.316 0.257 0.201 0.148 0.096 0.047 0.339 0.276 0.215 0.157 0.103 0,050 0.231 0.169
0.458 0.513 0.566 0.616 0 666
0.363 0.311 0.262 0.214 0.168
0.179 0.176 0.172 0.170 0.166
1,35052 1.34882 1.34719 1,34585 1.34425
64.1 63.5 62.9 62.4 62.0
0.077 0.152 0,222 0.290 0.354 0.416 0.475 0.532 0.587 0,639 0,079 0.155 0.227 0.296 0.362 0.425 0.485 0.543 0.081 0.158 0.232 0.303 0.369 0.434 0.083 0.162 0.238 0.309 0.085 0.166 0.087
0.383 0.374 0.367 0.388 0.350 0.343 0.336 0,329 0.323 0.317 0.480 0.468 0.457 0,447 0.437 0.427 0.419 0.410 0.580 0.566 0.553 0.540 0.528 0.516 0.686 0,669 0.652 0.637 0.797 0.776 0 853
1.35949 1.35795 1.36648 1,35607 1.38369 1.36205 1.35052 1.34892 1.34751 1.34605 1.35918 1.35753 1.35637 1.35502 1.35344 1.35202 1.35058 1.34899 1.35899 1,35253 1.35614 1.35481 1.35331 1.35198 1.35867 1.35734 1.35602 1,35457 1.35822 1.35690 1.35797
63.2 62.6 61.9 61.2 60.6 60.0 59.5 59.1 58.7 58.2 61.5 60 7 59 9 59 4 58 7 58.2 57.7 57,3 59.6 59.0 58,2 57.6 57.1 56 6 58 1 57.4 56 7 56 0 56 8 56 0 56 4
0.110
0.054 0.118 0.058 0.061
