INDUSTRIAL AND ENGINEERING CHEMISTRY
1952
Roozeboom, H. W. B., “Die Heterogenen Gleichgewichte VOII Standpunkte der Phasenlehre,” Vol. 3, Vieweg und Sohn, Braunschweig, 1913. Sage, B. H., Budenholzer, R. A,, and Lacey, W. N., IND. ENG. CHEM.,32, 1262 (1940). Sage, B. H., Hicks, B. L., and Lacey, W. N., Ibid., 32, 1085 (1940). Sage, B. H., and Lacey, W. N., Trans. Am. Inst. Mining Met. Engrs., 174, 102 (1948).
1675
114) Sage, B. H., and Lacey, W. N., “Volumetric and Phase Behavior of Hydrocarbons,” Stanford University Press, 1940. (15) Sage, B. H., Lavender, H. M., and Lacey, W. N., IND. ENG. CHEM.,32, 743 (1940). (16) Winn, F. W., “Simplified Nomographic Presentation of Hydrocarbon Vapor-Liquid Equilibria,” Houston meeting of -4.I.Ch.E. (1950). Rx.cErvEr, for review December
11, 1951.
ACCEPTEDFebruary 19, 1959.
Vapor Pressure-Composition Measurements on Aqueous Hydrazine Solutions JEROME 6. BURTLE College of S t . Thomas, S t . Paul, M i n n .
T
HE investigation herein reported was carried out several yewh ago when it became necessary to acquire distillation data on aqueous hydrazine solutions. Search of the literature showed that vapor pressure data in the water-hydrazine system were singularly sparse (%-7), especially in the subatmospheric range. To supply these missing values, the following results are reported. APPARATUS AND PROCEDURE
The apparatus employed consisted of a cyclic still provided with a total condenser and so arranged that an equilibrium sample of both liquid and vapor could be taken. This type of equipment haa been described by Sameshima ( 1 1 ) and by Smyth and Engel ( 1 3 ) . I n the equipment used in this work pressures were observed on a conventional mercury-in-glass U-tube, closed-end manometer, and were read by means of a cathetometer. Boiling temperatures were read on a thermometer suspended in the boiling liquid, Ail thermometers used were graduated in 0.1” C. intervals and were carefully calibrated against a Bureau of Standards thermometer and against pure compounds. The setup used in this investigation differed from that of Smyth and Engel in one important respect-the omission of the thermal stirrer. Since it has becn reported that hot metals catalyze the decomposlition of hydrazine (1) it was deemed advisable to eliminate the hot wire thermal stirring device of the Smyth and Engel apparatus. Instead, a glass wool ebullator was placed inside the boiling pot and, using a 5 ” t o 10” C. temperature differential between boiling pot and heating bath, smooth boiling without bumping was obtained.
TABLEI. EQUILIBRIUM PERIOD Temp.
C.’
50.1 50.1
Pressure, Mm. Hg 38.5 38.6
Boiling Time, Min. 60 30
was then continued for 30 minutes to allow the system to come to equilibrium. The equilibrium boiling period of 30 minutes was chosen when it was noted that duplicate samples showed no significant change in concentration on longer boiling. Results of a pair of typical experiments investigating the equilibrium period are shown in Table I. At the end of this period the liquid condensed in the vapor sample cup (approximately 5 grams) had the composition of the vapor in equilibrium with the liquid in the boiling pot. The pressures a8 indicated on the manometer and the boiling temperature were accurately recorded, all heaters ~~
TABLE11. VAPORPRESSURE-COMPOSITION DATAFOR HYDRAZINE SOLUTIONS AT CONSTANT PRESSURE Composition at Equilibrium
Preasure, Mm. Hg 124.8
281.8
411.2
Conen., G. NSHd100 G. Liquid Vapor 65.5 64.9 65.1 64.5
Stock solutions of concentrated hydrazine were appropriately diluted with distilled water and resulting samples (approximately 120 grams each) were placed in the vapor pressure equipment and a thermometer and the ebullator were introduced. The air in the apparatus was then replaced with nitrogen, the desired working pressure (as measured on the manometer) was attained by means of a vacuum pump and maintained constant by a manostat. When the conditions of pressure had become constant the heating of the sample in the boiling pot was started and continued until the pot contents had begun to boil. The mixture was allowed to distill until the vapor sample cup was filled. Heating
560.4
100.6
Boiling Temp., ’ C. 56.17 58.9 63.8 69.7 74.0 74.2 73.9 71.7 69.1 66.8 74.38 77.6 83.8 88.4 93.0 93.3 93.2 91.9 89.6 86.5 83.66 86.9 92.4 93 5 98.4 102.8 103.4 103.6 102.2 99 4 96.8 91.73 95.5 100.3 106.4 110.9 111.3 110.2 107.9 105.2 97.75 101.5 106.8 112.6 117.2 117.6 116 9 114.2 111.7
Vapor, Mole % Hz0 NzH4 100.00 ... 99.21 0.79 96.60 3.40 84.43 15.57 54.98 45.02 51.74 48.26 42.67 57.33 25.03 74.97 6.90 93.10 0.35 99.65 100.00 ... 99.21 0.79 94.00 5.94 86.79 13.21 60.54 39.46 54.05 45.95 42.67 57.33 22.74 77.26 10.69 89.31 0.54 99.46 100 IO0 99.15 0.85 95.41 4.59 94.61 5.39 85.21 14.79 62.16 37.84 50.88 49.12 55.92 44.08 24.75 75.25 90.30 9.70 1.40 98.60 100.00 98.98 1.02 95.22 4.78 83.86 16.14 42.11 57.89 45.23 54.77 78.12 21.88 90.63 9.37 1.40 98.60 100.00 99.60 .40 94.37 5.63 84.15 15.85 56.92 43.08 44,77 55.23 25.58 74.42 9.55 90.45 98.76 1.24 .
I
.
...
...
LI:q_uid, Mole % HzO NIHI 100.00 90.40 79.91 67.97 51.42 50.13 48.22 32.23 15.28 1.05 100.00 90.91 77.78 68.66 54.05 50.34 44.42 31.85 18.17 1.24 100.00 90.65 79.91 78.16 68.33 54.78 48,48 44.99 32.37 16.20 1.94 100.00 90.06 80.30 68.33 51.53 45.22 31.18 16.97 2.63 100.00 91.16 79.46 68.16 51.42 45.11 32.64 16.04 2.13
...
9.60 20 09 32.03 48.58 49.87 54.78 67.77 84.72 98.95
...
9.09 22.22 31.34 45.95 49.66 55.58 68.15 81.83 98.76
...
9.35 20.09 21.84 31.67 45.22 51.51 55.01 67.63 83.80 98.06
...
9.94 19.70 31.67 48.47 54.78 68.82 83.03 97.37
...
8.84 20.54 31.84 48.58 54.89 67.36 83.96 97.87
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
1676
Vol. 44, No. 7
/IO
4 /OS
P {OI?
P< 9 8
F fi
94
90 00
Of
Figure 2.
02
0.3 0 4 0 5 06 0 7 Mol Fraction Water
08
09
/O
Boiling Point-Composition Diagratn for Hydrazine Water S>stem
TABLE IV. ACCURACY OF EXPERIMENTS
Mol Fraction Water in Liquid
Figure 1.
Vapor-Liquid Equilibrium Data for HydrazineWater System
were then turned off, the maxlostnt was disconnected, anti nitrogt.11 was introduced into the apparatus until atmospheric pressure was restored. Contents of the boiling pot were cooled to,rooni temperature and sampled, as were the contents of the vapor sample cup. Both vapor and liquid samples were analyzed by titration with iodate (9, I O ) , amaranth being used as an internal indicator in the analysis of the very dilute solutions ( I O , 12). The concentrated stock solutions of hydrazine were provided by Western Cartridge Co. of East hlton, Ill., and were of two types. The first of these represented an aqueous solution analyzing a t approximately 97% hydrazine, mThile the second type was of higher concentration, 99.9+ %. The latter materials were used t o study the hydrazine-rich portions of the curves. RESC'LTS
The data obtained in thcse experiments are presented in Table I1 and graphically in Figures 1 and 2. All of the curves show the expected maxima associated with the hydrazine-water azeotrope. The 2-y diagrams a t all pressures are very similar in shape. The same thing is true of the vapor pressure-composition diagrams. Only one example of each type of curve is included to serve as a sample for the graphical presentation of the data. The composition of this azeotropic mixture remains fairly constant over the entire pressuw range a t a value in the neighborhood of 53 to 55 mole hydrazine (see Table 111).
r0
OF PRESSURE o s AZEOTROPIC COVPOSITIOS TABLE 111. EFFECT
Pressure, Mm. Hg 124.8 281.8 411.2 560.4 700.6
Composition, 31ole % ' Hydrazine 53 54 55.3 55 54
Extrapolation of the data obtained in this investigation indicates a boiling point of 113.8' C. for pure hydrazine a t 760 mm. pressure. This value is in agreement both with the 113.5' C. boiling temperature reported by Bjorlrman ( 2 ) and by Fresenius and Karweil ( 4 ) and with the value of 114.15' C. reported by Hiebner and Woerner (6). Very rough extrapolation of the data presented suggests that the boiling point of the azeotrope a t
Composition, Mole Obsvd. Boiling _____ % Ccl4 .___ Pressure, Standard Temp., C. Liquid Vapor Mm. Hg 12.8 Benzene50 0 15.3 274.5 27.3 CClr mix30.0 31.1 281.5 39.1 ture (14, 50.0 42.2 287.0 50.4 53.0 292.5 49.9 51.7 54.6 291.5 50.0 50.6 53.8 293.0 50.0
.. .. ..
..
60.3 116.0
240.5 245.0
Reported Pressure, Mm. Hg 278.5 284.7 294.7 298.5 299.9 298.7 60.54 116.38 239.8 244.9
Error,
% ' 1.4 1.1 2.6 2.0 2.8 1 9 0.1 0.3 0.3 0.01
760 nim. is approximately 120" C. This ia to be comparcd with the value of 120.1" C. reported by de Bruyn ( 3 ) and t,hitt of 119" C. reported by Bjorkman. The equipment used in this invest.igation \vas calibrated against pure compounds and against benzene-carbon tetrachloride mixtures. Results of these experiments shov-ed that the equipment is highly accurate over the composition ranges close to the pure compound regions. In the central portions of the curve, those dealing with mixtures, accuracy is not so great. Data obtained on benzene-carbon tet'rachloride mixtures show agreement within 1 to 3% of those of ZaTvidski ( 1 4 ) . Accuracy data are presented in Table IV. ACKNOWLEDGW ENT
The author wishes to express his appreciation t o \Vestern Cartridge Co., East Alton, Ill., for the research grant that made this work possible and for generously providing the hydrazine used in the investigation. Acknowledgment is also made to L. F. Audrieth, professor o f chemistry a t the University of Illinios, for his vduable advice and suggestions. LITERATURE CITED
Audrieth, L. F., and Ogg, B. A., "The Chemistry of Hydrazinc,," pp. 87, 96, 148, Sew York, John Wiley & Sons, 1951. ( 2 ) Bjorkman, A., Snensk Kern,, Tid., 59, 211 (1947). (3) de Bruyn, C. A. Lobry, and Dito, J. W., Proc. KoriinkZ. S e d e r land. Akad. Wetenschap., 5, 171 (1902). ( 4 ) Fresenius, W., and Karnreil, J., 2. p h y s i k . Chem., B44, 1 (1989). ( 5 ) Gmelins, "Handbuch der Anorganisohen Chemio," 8th etl., 1-01, 23, p. 548, Berlin, Verlag Chemie, 1936. (6) Hiebner, W., and Woerner, A , Z. EZektrochem., 40, 252 (1934). (7) Huffman, H. M., et al., J . Am. Chem. Soc., 71, 2293 (1949). (8) "International Critical Tables," 1st ed., Vol. 3 , p. 213, Xew York, McGraw-Hill Book Co., 1928. (9) Kolthoff, I. M., J . -4m. Chem. SOC.,46, 2009 (1924). (10) Penneman, R. A., and hudrieth, L. I?., A.naZ. C'hem., 20, 1058 (1)
(1948). (11) Sameshima, J., J . Am. Chem. Soc., 40, 1482 (1918). (12) Smith, G. F., and Wilcox, C. S.,ISD. ENG.CHEY., ANAL.ED., 14, 49 (1942). (13)
Smyth, C. P., and Engel, E. W., J . Am. Chem. SOC.,51, 2G4.B
(14)
Zawidski, J. V., Z.physik. C h e m , 35, 129
(1929).
RECEIVED for review July 13, 1961.
(1900).
ACCEPrED
March 10, 1952.
