838
ANALYTICAL CHEMISTRY
conductance. Similar wsultR were found for the tetrahydrofuran-water-potassium chloride system. It is noted that the concentration of potassium chloride in each solution could be determined from c u r v c relating concentration of potassium chloride to low-frequency conductance a t each dielectric constant value. These data :ire not included in the present report. I n general, the method appears t o be satisfactory for the determination of the dielectric constant of a solvent mixture in which the components of the mlvmt and the nature of the electrolyte are knoivn. When the result,< for the dior:ine-i~:~ter-potassiurii chloi~ide system are compared with results for which either the components of the solvent or the nature of the electrolyte are altered, a number of interesting observations may be made. Typical data for such comparisons :ire shown in Tahle 11. Substitution of sodium chloride for potassium chloride in any solution produced negligible change for the value of the dielectric constant of the solvent as determined by this method. Substitution of ,solutes having bivalent. ions aln-:iy,* yielded dielectric constant values which were too high; the error inrreawl regularly Kith increasing concentrat,ion of electrolyttn. This is illustrated by the data for 33.8y0dioxane-m.ater-col,l,(.I' sulfate of Table 11. These differences are greater for niisturc- of low dielectric constant than for pure water. For exiiniplr, :it a specific conductance of 150 X 10-5, a solution of magntsiuni sulfate i n \rater yields a dielectric constant which is only nhout 0.6 unit too high. The conclusion of Blaedel, Malmst,adt, I'etitjciin, nncl Anderson (g), of Hall ( 6 ) , and of Reilley and ?*IcCurtly ( 8 ) that for any given solvent tho tranRfcr plot is a uniqur function of the ordinary conductance appears to be valid only :I* an uppro\;iniation, being most nearly correct in water solution. With data thus far available it is not possible to tlctcrniinc the relative importance of the various factors which contribute to these differences. The concentration of electrolyte required to produce a given conductance increases as the solvcnt dielectric constant decreases and this should have an effect on the over-all dielectric constant of the solution. I n addition, the differences in the conductance of the solution a t 1000 cycles :ind a t 20 mcgacycles may be significant, though a t present it is believed t,httt these effecte are responsible for only a small part of the total error. For dctermination of the dielectric constant of the solvent' by
the method described here, where other solvent systems are compared with dioxane-water, the precision is good for solvent dielectric constants greater than 50. For such solutions the results of Table I1 show that the accuracy is about the same as for solutions in which the solvent being determined has the same components as the solvent upon which the calibration curves were based. As 6he dielectric constant is lowered below 50 (as a nonaqueous system is approached), the calculated dielectric constants show an increasing deviation which also increases regularly with concentration, but the algebraic sign of the deviation appears to depend upon the particular solvent system chosen. Thus pure methanol and a methanol-dioxane mixture show dielectric constants which are too low while mixtures rich in tertbutyl alcohol and tetrahydrofuran yield dielectric constants which are t'oo high. The precise analysis of such systems requires calibration curves based upon the same solvent components. ACKNOWLEDGMENT
This work was a joint undertaking of the Department of Chemistry of West Virginia University and the Office of Ordnance Research, U. S. Army. The tetrahydrofuran used was furnished by the Electrochemicals Department, E. I . du Pont de Nemours & Co. LITERATURE CITED (1) Blaedel,
W.J., Burkhalter, T. S., Flom, D. G., Hare, G., and
Jensen, F. W., ANAL. CHEM.,24, 198 (1952). (2) Blaedel, W. J., Malmstadt, W.V.,Petitjean, D. L., and Anderson, W.K., Ibid., 24,1241 (1952). (3) Critchfield, F. E., Gibson, J. A , , Jr., and Hall, J. L., J . Am. Chem. Soc., 75, 1991 (1953). (4) Ibid., p. 6044. (5) Fischer, R. B., ANAL.CHExi., 19,835 (1947). (6) Hall, J . L., Ibid., 24, 1236 (1952). (7) Hall, J. L., and Gibson, J. Ai., Jr., I b i d . , 23, 966 (1951) (8) Reilley, C. N., and hIcCurdy, W. H., Ibid., 25, 86 (1953). (9) Sinelair, D. B., Proc. I m t . Radio Engrs., 28, 310 (1940). (10) West, P. W., Burkhalter, T. S., and Broussard, L., ANAL.CHE 22,469 (1950). (11) West, P. W., Robichaux, T., and Burkhalter, T. S., I b i d . , 23, 1625 (1951). (12) West, P. W., Senise. P., and Burkhalter, T. S., Ibid., 24, 1250 (1952). RECEIVED for reriew September 22, 1953. Accepted February 16, 1954. Presented before the Division of Analytical Chemistry a t the 124th hleetin!: of the ERICA AN CHEMICAL SOCIET.;,Chicago, 111.
Analysis Data for the Ternary System Isopropyl Alcohol-Isopropyl Ether-Water WALLACE S. BREY, JR.' St. Joseph's College, Philadelphia, Pa. '1.0 permit anal>-siao f the products of isopropyl alcohol
dehydration, values of the refractive index, density, and viscosit:- hal-e been measured at 25" C. for isopropyl alcohol-isopropyl etherw-ater solutions. Numerical results are presented for mixtures at 5% composition intervals throtrghou t the r e g i o n of nliscibility, and, where possible, these are compared with data from the literature. The ranges of composition oyer which various combinations of the physical properties are best suited for analytical purposes are indicated. .Analysis of synthetic mixtures with uncertainties of 0.10 to 0.25 weight 70 water, 0.23 to 0.65 weight 70 alcohol, and 0.15 to 0.50 weight o/o ether is possible. Analyses of reaction products carried out by the method appear to be correct within 0.5 to 1.0 weight Yc.
I
Tu' ORDER to facilitate the analysis by physical methods of
isopropyl alcohol-isopropyl ether-water mixtures which were produced during an investigation of alumina-catalyzed dehydration reactions, the refractive indices, densities, and viscosities of binary and ternary solutions of known composition have been measured a t 25' C. Data previously reported for this system have been fragmentary and often inconsistent. EXPERIMENTAL
Materials, Distilled 1~ater was redistilled from acid permanganate. Eimer and Amend C.P. isopropyl alcohol was further purified by refluxing over calcium oxide followed by distillation through a 16-plate Snyder column. As extreme care is 1
Piesent address, Uni\ ersity of Florida, Gainesvdle, Fla
V O L U M E 2 6 , NO. 5, M A Y 1 9 5 4
839
necessary to eliminate absorption by the alcohol of water from the air ( I d ) , it was more convenient to correct the compositions of mixtures for the water content of the alcohol, as determined by Karl Fischer titration, than to prepare absolutely anhydrous material. The alcohol as used contained 0.04 to 0.30% water, and boiled between 82.0" and 82.2" C. The isopropyl ether was Eastman Kodak White Label reagent; refluxing over calcium oxide followed by distillation made no measurable difference in the physical properties and most of the ether was used as received. Procedure. Each mixture was made up by running the desired volumes of liquids from burets into a tared 50-ml. glassstoppered volumetric flask in the order water, alcohol, ether. The flask and contents were weighed after each addition. For determination of densities, specific gravity bottles of approximately 25-ml. capacity were employed. The bottles were provided with ground-in thermometers and capillary side arms. A pycnometer and contents were brought to temperature in a water bath a t 25" =!= 0.02" C. the excess liquid was wiped from the capillary opening, and the pycnometer was removed from the bath, quickly dried, and immediately weighed. Water was used for calibration of the pycnometers, and the calculated densities were corrected to vacuum. Indices of refraction for the sodium D line were measured a t 25" =k 0.1' C. on a Bausch & Lomb Bbbe refractometer, which had been standardized with a glass prism of known index of refraction and which was checked regularly with freshly redistilled water. Viscosities were measured either in an Ostwald tube, in which the time of flow for water was 45.7 seconds, or in a CannonFenske Series 50 tube, for which the time of water flow was 221.7 seconds; the tubes were suspended in a water bath a t 25" =!= 0.02" C. Calibration was carried out with methyl
Table I. Alcohol, Weight
%
0 5 10 15 20 25 30 35 40 35 45 40 50 45 40 55 50 45 60 55 50 45 65 60 55 50 45 70 65 60 55 50 75 70 65 60 55 50 80 75 70 65 60 55 50 45 85 80 75 70 65 60 55 50 45 90
85 80
alcohol (e), with ethyl alcohol ( d ) , and with aqueous sucrose solutions (1) as standards. For solutions with an ether content exceeding 75$& the viscosity is quite low and also rather insensitive to composition. Thus in this range i t was not considered worth while t o attempt calibration or correction for the kinetic energy errors which are relatively large for solutions of low flow time. RESULTS
I n Table I are presented data for mixtures a t 5% weight intervals of composition over the region of miscibility as well as for 14 other mixtures with compositions near the region of immiscibility. For each composition entry in the table a t least one and generally two or more mixtures falling within 0.201, of the indicated composition were made up and measured. When necessary, the results were then recalculated to the round percentages tabulated. The density values given in the table are relative to the density of water a t 4" C. Measured for independently prepared mixtures of the same composition, the densities were reproducible within 0.0001 unit; density values are thought to be known with an error not greater than this. Since the instrumental uncertainty in refractive index is 0.0001 unit, some of the observed values were smoothed by corrections of 0.0001 to obtain the tabulated values. Viscosity results were found to be reproducible within 2 parts per thousand except for a few obviously erratic results such as are occasionally encountered in this type of measurement. I n addition to the absolute viscosity in centipoises there is given also
Refractive Index, Density, and Viscosity of Mixtures of Isopropyl Alcohol, Isopropyl Ether, and Water Ether, Weight
Refractive Index, n
2z
Density,
0 0 0 0 0 0 0 0 0 5 0 5 0
1.3325 1.3368 1.3413 1 ,3458 1.3503 1.3541 1 3574 1 ,3601 1 ,3626 1.3621 1.3649 1.3643 1 ,3669 1.3665 1.3659 1 ,3685 1.3683 1.3678 1,3700 1 ,3699 1.3696 1.3690 1.3715 1.3713 1.3711 1 ,3707 1.3700 1 ,3729 1 ,3726 1 ,3724 1,3721 1.3718 1,3739 1.3737 1.3735 1.3733 1 ,3731 1,3727 1 ,3747 1.3746 1.3745 1.3743 1.3740 1.3737 1.3734 1 ,3729 1 ,3753 1.3751 1 ,3750 1.3749 1.3747 1.3744 1.3741 1.3738 1 ,3735 1 ,3756 1 ,3753 1.3752
0.99707 0.9884 0,9810 0.9740 0.9666 0.9580 0.9478 0.9369 0.9256 0.9212 0.9140 0.9102 0,9022 0.8986 0.8941 0.8904 0.8870 0.8834 0.8786 0.8754 0.8719 0.8682 0.8668 0.8639 0.8606 0,8572 0.8529 0.8549 0.8522 0.8492 0.8460 0.8426 0,8430 0.8403 0 8375 0,8346 0.8314 0.8281 0.8310 0,8284 0.8257 0.8230 0,8200 0.8167 0.8136 0.8100 0.8189 0.8164 0.8138 0,8111 0.8084 0.8054 0.8024 0.7994 0.7964 0.8067 0.8042 0.8016
70
5 10 0 5
10 0
5 10 15 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 25 0 5
10 15 20 25 30 35 0 5 10 15 20 25 30 35 40 0 5
10
di5
Viscosity CentiCentistokes poises 0.894 1.132 1.424 1.773 2.130 2.453 2.730 2.964 3.151 3.085 3.290 3.207 3.391 3,295 3.269 3.444 3.330 3.236 3.452 3.320 3.189 3.101 3.411 3.280 3.126 2.987 2.902 3.331 3.174 3.020 2.869 2.716 3.213 3.052 2.889 2.724 2.565 2.416 3,062 2.896 2.729 2.553 2.394 2,237 2.084 1.940 2.899 2.714 2.531 2.364 2.204 2.048 1.898 1.764 1.629 2.732 2.532 2.350
Alcohol, Weight
%
Ether, Weight
Density,
7c
Refractive Index, n '2
15 20 25 30 35 40 45 50 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 1 2 4 8 14 17 24 29 41 47 54 60 75 85
1 ,3751 1 ,3750 1,3748 1,3746 1,3743 1,3740 1.3736 1.3731 1 ,3757 1,3755 1.3753 1.3751 1 ,3749 1.3747 1.3744 1.3741 1,3738 1.3734 1 ,3730 1,3726 1.3721 1.3716 1.3711 1.3751 1.3749 1.3747 1.3744 1,3741 1.3738 1 ,3734 1.3730 1 ,3726 1,3722 1.3717 1.3712 1 ,3707 1,3702 1.3696 1.3690 1.3684 1.3677 1.3670 1.3663 1.3666 1 ,3469 1,3553 1,3591 1.3631 1.3671 1.3687 1,3712 1.3721 1,3731 1.3728 1 ,3727 1.3721 1.3703 1.3688
0.7990 0.7964 0.7935 0.7906 0.7878 0.7848 0.7819 0.7784 0.7942 0.7916 0.7891 0.7866 0.7838 0.7810 0.7782 0.7754 0.7725 0.7696 0.7667 0.7636 0.7606 0.7575 0.7543 0.7808 0.7782 0.7756 0.7730 0.7702 0.7673 0.7644 0.7614 0,7585 0.7556 0.7526 0,7495 0.7464 0.7433 0.7402 0.7371 0.7339 0.7306 0.7271 0.7234 0.7192 0,9724 0.9524 0.9354 0.9113 0.8793 0.8660 0.8394 0.8250 0.7974 0.7872 0.7757 0.7676 0.7485 0.7366
d:'
Viscosity CentiCentistokes poises 2.171 1.735 1.595 2.003 1.846 1.465 1.703 1.346 1,237 1.570 1.438 1.129 1.332 1,041 1.229 0.957 2.068 2.604 2.386 1.889 1.719 2.178 1.981 1.558 1.809 1.418 1.647 1.286 1,169 1.502 1.370 1.062 1.254 0.969 1.153 0.887 0.811 1.058 0.968 0,739 0.893 0.679 0.625 0.825 0.575 0.762 2.639 2,061 2.327 1.811 2.059 1.597 1.414 1.829 1.624 1.251 1.448 1.111 1.296 0,991 1.168 0.889 0.799 1.054 0.953 0.720 0.865 0.651 0.790 0.592 0.723 0,540 0.669 0.497 0.623 0.461 0.428 0.581 0.400 0,545 0.513 0.375 0.486 0.353 0.462 0.334 0.439 0.316 1.829 1.779 2.519 2.399 2.868 2.683 3.269 2.979 3.313 2.913 2.715 3.135 2.622 2,201 2,293 1 .a92 1.631 1.301 1.389 1.093 1.144 0.887 0.751 0.979 0.687 0.514 0.415 0.563
A N A L Y T I C A L CHEMISTRY the kinematic viscosity in centistokes, which, aside from possible end and kinetic energy effects, is proportional to the actual time of flow and is therefore of more direct application in analysis. COMPARISON WITH THE LITERATURE
Densities of alcohol-watei mivtuies have also been determined a t other temperatures. The most careful work is that of Langdon and Keyes (12)a t 35" C. If their results, those of the present work a t 25" C., and those reported for 15' C. (10) are compared, the density-composition curves have very nearly the same shape, with an almost linear variation of density with temperature for any given composition. The densities quoted by reference books for 20" C. ( I O , 18)are based on interpolation from measurements of 10 scattered compositions (IS), and, because of the nonlinear density-composition relation, some of the values cited for mistures of high water contents are substantially in error and cannot he used for interpolation a t intermediate temperatures, The densities of binary mixtures of alcohol and ether given here agree for the most part exactly with those found by Miller and Bliss ( 1 4 ) , although several values of these workers show appaiently random scattering. Frere ( 9 ) reported densities of saturated solutions of the thrre components; the values obtained in this laboratory are consibtent with his data, differing by not over 0.0002 unit and usually by 0.0001 unit or less. The variation of density with composition exhibits a rather sharp change as the solubility limit i- a i r proached. Viscosities. The viscosity of \3ater at 25" C. was taken as 0.891 centipoises which corresponds to the recently adopted National Bureau of Standards value of 1.002 cp at 20" C. The measured viscosity of isopropyl alcohol is 2 001 cp., intermediate between the values of 2.048 cp. of Parks anti Kelley (17 ) and 2.08 cp. of Olsen and Washburn (16). .4ssuniing a linear variation of log viscosity with reciprocal of absolute temperature, a value for 25" C. interpolated from the viscosities of Timmernians and Dclacourt ( 2 1 ) for 15' and 30" C is 2.062 cp Other values in the literature range from 2.01 c'p. ( 2 2 )to 2.18 vp. ( 2 5 ) . Viscosities of water-alcohol mixtures have been measured by Whitman and Hurt ( 2 5 ) and by Olsen and Washburn (16). Below 20% alcohol results of both coincide nith those of the present work. Above 20% alcohol ing divergence there is increasamong
Refractive Indices. The refractive index of isopropyl alcohol is found to be 1.3751 as compared with previous values of 1.3747 (5), 1.3749 (24), 1.3750 ( 1 7 ) , and 1.37538 (2.2). For isopropyl ether, Driesbach and hIartin (8) reported n g as 1.36618, in rontrast with the present value of 1.3656. They stated that their ether was 99.36 mole % pure with a density of 0.7230 a t 25" C. This density does not seem to he in agreement with the results of most workers for ether of this purity. If the values given by Driesbach and Martin for the refractive index and the density a t 20" C., 1.36888 and 0.72813, respectively, are compared with the corresponding figures given for 20" C. by Vogel (M), which are 1.36823 and 0.7257, the values cited by the former are both seen to be slightly high; it appears that the same may be true of their values for 25' C. Earlier, Snyder and Gilbert (20) found n z to be 1.3660 for the ether. The refractive indices determined for water-isopropyl alcohol mixtures show a variation with composition which closely resembles in form the variation previously found a t 15" C. (7), including a maximum a t about 94% alcohol. Two sets of data have been reported for 20' C.; one of these lacks precision (191, and the other apparently diverges widely from the correct variation with composition (S). Densities. The density of isopropyl alcohol has been given variously as 0.7803 ( I n ) , 0.7807 (25), 0.7808 (5, 11, 24), 0.7809 (16, f ; ) , 0.7810 (14, 21), 0.7811 (22), and 0.7812 (16). Values of 0 7811 to 0.7812 were obtained in the present work for alcohol which had been in contact with air if only for a short time; this material was found by the Karl Fiecher method to contain water. Several measurements of density on alcohols containing from 0.30 down to 0.04% water were made; extrapolation of the results of these determinations yields 0.7808 for the density of the anhydrous alcohol. Miller and Bliss ( 1 4 )found densities of isopropyl ether varying from 0.7187 to 0.7195 and used 0.7191. Frere (9) reported 0.7210 for 0.5 weight % water in ether, which indicates for pure ether a density coinciding with the present result, 0.7192. The the three sets of values: higher densities obtained by Driesbach and Martin have been those of Khitman and discussed above. For binary mixtures of alcohol and \vater, densities a t 25" C. have been determined by a number of workers. Batscha and Reznek ( X ) gave results for solutions containing less than 25 volume % isopropyl alcohol. Recalculation of their compositions to weight per cent gives values of density which deviate from the present results by 0.0001 unit or less for mixtures I-ontaining up to 15% alcohol, but are as much as 0.0010 unit larger at 20% alcohol. Wilson and Simons (86) have recently measured densities in this binary system a t intervals of approximately 10 mole %. Their remlts were found to fall, on a large scale plot, within 0.0001 unit or less of the best curve drawn through the present density values. However, only one of the mixtures measured by Wilson and Simons contained less than 45 weight % alcohol. Earlier values for the same system (16, 26) are for the WEIGHT PER CENT ETHER moRt part 0.0002 to 0.0005 unit higher Figure 1. Refractive Index of System Isopropyl Alcohol-Isopropyl Ether-Water than those here obtained. at 25" C.
ho
V O L U M E 26, NO. 5, M A Y 1 9 5 4
841
resulting from possible variation in the ether-alcohol ratio, of not over 0.2%. When the ether content exceeds io'%, the lines of constant refractive index, constant density, and constant viscosity are practically parallel, and measurement of these properties gives analytical results of limited accuracy-i.e., alcohol content to no better than 2 or 3% Refractive index variation is so small when the water content is less than 20% that lit'tle information is obiainable in this region. There are some combinations of density and viscosity which occur for two different compositions in the vicinity of the saturation curve and 40% water. These mistureu must be distinguished by the values of refractive index. For several representative niistures there are listed in Table I1 magnitudes of the uncertainty i n analytical rcsrilts \Then the most suitable pair of properties is eniployed to estimate the composition. I n calculating these valuen of possible analytical variation, the uncertainty in density x a s taken as 0.0002 unit, that in refractivr 2c index as 0.0002 unit, and that in viscosity as 2 parts pry 0 10 20 30 40 50 60 70 80 thousand. The possible deviation WEIGHT PER CENT ETHER of the composition estimate deFigure 2. Density and Viscosity of System Isopropyl Alcohol-Isopropyl E t h e r pends not only upon the esWater at 25" C. perimental error in measurements - - - _. Denaity. Values are given inside triangular grid -. Viscosity. Values are given a t edge of diagram of the individual propertirs but also upon the angle a t which lines representing constant values of the greater than those reported herein over most of the range, properties mutually intersect. while those of 01-n and Washburn are from 0.01 to 0.06 rp. In Table I11 are included some results for the liquid products greater. of dehydration of isopropyl alcohol over aluminum oxide. For some mixturps there are given for purposes of comparison the water contents as determined by the Karl Fischer method In addition, the self-consistency of the analyses for samples for n hich Table 11. Calculated Cticertainty in Composition of all three properties were measured is indicated by comparison of Typical Mixtures the compositions estimated from diff erent pairs of propertieApproximate Composition, -4nalytical Uncertainty, Weight % Weight % The possible appearance of reaction by-products in the mixtures Water Alcohol Ether Kater Alcohol Ether made it desirable to have an independent check on the annlvses, GO
0.20a 0.25 0.15 5 0.15 3 5 0.10 50 10 0.20' 10 10 0.10 ;3 3 15 0.15 20 20 0.15 20 0.15 35 0.10 J 55 0.20 Based on density and refractive Index. Other 50 40 24
j
and \-iscosity.
5 5 5
0 . 3sn 0.65 0.30 0.35 0.25 0 . 60D 0.35 0.45 0.35 0.40 0.35 0.55
0 , 4.5'l 0.30 0.20 0.25 0.15
0.45a
0.25 0.30 0.25 0.30 0.25 0 40 values based on density
Table 111. Analyses of Reaction Products Veasured Properties -~ KineCompositions. Derived matic viscosity, Weight % n% d: cs. Water Alcohol Ether 1.3745 1.3704
1 ,3713
0.8213 0.8668 0.8406 0.8168 0.7954 0.7982 0.8138 0.7927 0.8564
2:900 2.614 2.185 2,378 2.547 2.394 3.083
1 ,3694
0.8748
3.256
1.3668
0.9016
3.314
1.3732
0.8338
2.815
1.3728
0,8444
2.886
... , . .
ARALYTICAL APPLICATIONS
In Figure 1 are plotted lines of constant index of refraction and in Figure 2, lines of constant density and constant kinematic viscosity, for most of the composition range covered. The curves of limiting solubility in thew figures are taken from the \vork of Frere (9). For mixtures containing is% water or more, it is apparent that all three properties are principally sensitive to water content and do not give useful information about the ether-alcohol ratio. Measurement of either density or viscosity in this region permits calculation of water content with an uncertainty, including that
...
... ,..
, . .
19.0s 37.5a 26.7 15.9 8.1 8.1 14.9 5.5 33.5 33.6a 40.5 40.8a 50.7 50.4" 23.4 25.4a 28.8 28.P
67,4" 53.2a 62.0 75.5 79.1 84.5 75.7 89.5 55.9 55.2a
52.Oa 51.1 45.8 46.6" 67.0 6 0 . Oa 57.8 58 20
a Based on density and refractive index. based on density and viscosity.
13.tja 9.3a 11.3 8.6 12.8 7.4 9.4 5.0 10.6 11.20 7.5 8.la 3.5 3.0a 9,6 14.6a 13.4 13.0"
Water. by Karl Fischer Titration.
%
19.3 37.7 27.2 17.0 8.06 8.85 15.8 5,73
...
... ,..
... 28.9
Other derived values are
842
ANALYTICAL CHEMISTRY
as by the Karl Fischer titration or by a materials balance on the reaction. Complete cross-comparisons for each of several mixtures by all the available methods showed that when by-products appeared discrepancies were evident on application of any one of the single check methods represented in Table 111. ACKNOWLEDGMENT
The support of a generous grant from the Research Corp. is gratefully acknowledged. Appreciation is due George J. Stockburger, who made some of the experimental measurements. LITERATURE CITED
(1) Bates, F. J., Natl. Bur. Standards, Circ. C440, 671 (1942). (2) Batscha, J., and Reanek, S., J . Assoc. Ofic. Agr. Chemists, 20, 107 (1937). (3) Bennett, C. T., and Garratt, D. C., Perfumery and Essentl. Oil Record, 16,18 (1925); International Critical Tables, Vol,. VII, p. 68, New York, McGraw-Hill Book Co., 1930. (4) Bingham, E. C., and Jackson, R. E., B u r . Standards Bull., 14, 59 (1919). (5) Brunel, R. F., J . Am. Chem. SOC.,45, 1334 (1923). (6) Carr, C., and Riddick, J. A., I n d . Eng. Chem., 43, 692 (1951). (7) Dorosaewskii, A. G., and Dworsancayk. S. V., Tables annuelles
internationales de constantes e t donnkes nurneriques, Vol. 11, p. 756, Paris, 1913; International Critical Tables, Val. VII. p. 68, New York, McGraw-Hill Book Co., 1930. (8) Driesbach, R. R., and Nartin, R. A,, I n d . Eng. Chem., 41, 2875 (1949).
(9) Frere, F. J., Ibid., p. 2365. (10) International Critical Tables, Vol. 111, p. 120, New York, McGraw-Hill Book Co., 1930. (11) Kretschmer, C. B., and Wiebe, R., J . Am. Chem. Soc., 74, 1276 (1952). (12) Langdon, W. M., and Keyes, D. B., I d . Eng. Chem., 35, 459 (1943). (13) Lebo, R. B., J . Am. Chem. SOC.,43, 1005 (1921). (14) -Miller, H. C., and Bliss, H., I n d . E n g . Chem., 32, 123 (1940). (15) Olsen, A. L., and Washburn, E. R., J . Am. Chem. SOC.,57, 303 (1935). (16) Olsen, A. L., and Washburn, E. R., J . Phys. Chem., 42, 275 (1938). (17) Parks, G. S., and Kelley, K. K., Ibid., 29, 727 (1925). (18) Perry, J. H., “Chemical Engineers’ Handbook,” 3rd ed., p. 191, New York, McGraw-Hill Book Co., 1950. (19) Schurnacher, J. E., and Hunt, H., I n d . Eng. Chern., 34, 701 (1942). (20) Snyder, H. B., and Gilbert, E. C., Ibid., 34, 1519 (1942). (21) Timmermans, J., and Delacourt, Y., J . chim. phys., 31, 105 (1934). (22) Trew, V. C. G., and Watkins, G. M. C., Trans. Faraday Soc., 29, 1310 (1933). (23) Vogel, A. I., J . Chem. Soc., 1948, 616. (24) Washburn, E. R., Brockway, C. E., Graham, C. L., and Deming. P., J . Am. Chem. Soc., 64, 1886 (1942). (25) Whitman, J. L., and Hurt, D. M., Ibid., 52, 4762 (1930). (26) Wilson, A., and Simons, E. L., I n d . Eng. Chem., 44, 2214 (1952). RECEIVED for review November 16, 1953.
Accepted February 3, 1954.
Distribution of Strontium within Barium Sulfate Precipitated from Homogeneous Solution LOUIS GORDON, CARL C. REIMER’, and BENJAMIN P. BURTT Department of Chemistry, Syracuse University, Syracuse 70,
The coprecipitation of strontium with barium sulfate is reported. Fractions of the carrier were precipitated from homogeneous solution by the hydrolysis of methyl sulfate in methanol-water medium. Residual barium was determined by a complexometric titration procedure using tetrasodium ethylenediamine tetraacetate as titrant. Strontium measurements were made using an equilibrium mixture of strontium-90 and daughter yttrium-90; Kirby’s equation was used for the interpretation of all counting rates. Evidence is presented for the existence of a supersaturated condition during the initial stages of the precipitation. A comparison of the conventional precipitation procedure with the homogeneous method indicates that the latter more nearly approaches equilibrium formation of the carrier compound. Over initial barium to strontium concentration ratios of 1.3 to 2700, strontium appears to be heterogeneouslydistributed throughout the solid phase; the heterogeneous distribution coefficient, A, in the Doerner-Hoskins equation was found to be 0.030 0.004 at 83”. This investigation emphasizes the problems involved in obtaining results in studies of this type of derichment system.
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N. Y.
I n 1926, Hahn (1.2)pointed out that “an element will only be precipitated from dilute solutions with a crystalline precipitate if it is bound with the crystal structure of the precipitate so that mixed crystals can form.” Later Hahn (11) classified carrying processes under several general headings including coprecipitation via isomorphous or isodimorphous replacement, adsorption, and internal adsorption. The distribution of a trace ion incorporated into host lattices usually conforms to either of two limiting laws. The first, describing the homogeneous distribution of a tracer ion within the solid carrier compound, is the familiar Berthelot-Kernst distribution law for the equilibrium partition of a solute between two immiscible phases. This law has been expressed by Henderson and Kracek ( I S )in a related form ( 3 )which permits the direct use of measured quantities of the tracer and carrier materials:
(?er) =D(%) carrier carrier solid
solution
This distribution law is assumed to be valid for the case where the ions in solution are in equilibrium with all of the ions in the entire solid phase. A heterogeneous distribution law was derived by Doerner and Hoskins ( 5 )for use in a study of the coprecipitation of radium in barium sulfate:
W
H E N an ion is separated from solution in the form of an insoluble salt, foreign ions are invariably removed as well. The term “coprecipitation” is used here to represent the simultaneous deposition of normally soluble foreign substances with a precipitate. 1
Present address, E. I. du Pont de Nemours & Co., Waynesboro, Va.
Doerner and Hoskins expected that this logarithmic distribution law would hold for any isomorphic salts formed by two similar elements with a common ion under experimental conditions
