INDUSTRIAL AND ENGINEERING CHEMISTRY
298
Vol. 38, No. 3
DISCUSSION OF RESULTS TABLE
PRESSURE, 11. TOTAL IN THE
PRESSURE, AND DENSITY SYSTEM SH4NOD-NH,-H~0AT 35 O C.
Compn. of S o h Wt. % NHa NHdNOs 5 47.4 71.3 10 0 22.4 44.9 67.6 0 l5 21.2 42.4 63.8 20 0 19.9 39.9 60.1 25 0 18.7 37.4 30 0 17.4
s"
in
G~~ phase, 1'01. % 79.1 87.0 78.2 83.7 90.0 93.8 86.6
90.3 94.3 96.9 91.4 94.0 96.6 98.6 94.6 96.4 98.0 96.8 98.1
PARTIAL
Vapor Pressure, Mm. HgPartial Partial Total of NH3 of H20 135 107 28 22 173 151 41 189 148 182 35 217 26 257 231 21 336 315 301 261 40 348 314 34 421 397 24 552 535 17 465 425 40 534 502 32 628 22 650 842 12 854 37 678 641 762 28 790 933 19 952 32 998 966 1128 1107 21
Density, G./Cc.
1.167 1.276 0.950 1.031 1.121 1.218 0.931 1.003 1.078
1,164
0.914 0.977 1.040 1.113 0.898 0.952 1.004 0.881 0.928
ture of the liquid phase was lowered to 10" C., and measurements of the total pressure and the composition of the vapor phase were made by a procedure analogous to that employed a t 35" C. I n the present work the total pressures were read from the manometer by means of a mirror scale. The readings invariably agreed within * 1.0 mm. with those obtained in previous, unpublishedwork inwhich the total pressures were read with a cathetometer. MEASUREMENT O F DENSITY
The apparatus for measuring the densities of the solutions consisted essentially of a pycnometric bulb of about 20 ml. capacity and a n expansion bulb of about 10 ml. capacity. The tT7-o bulbs were connected as shown in Figure 2. The solution under test was heated to 35" C. in the flask in which it had been prepared and was transferred directly to the tared density apparatus. The apparatus was filled to a point slightly above the central stopcock (Figure 2 ) . For solutions having a vapor pressure greater than the atmospheric pressure, the upper stopcock was manipulated to maintain a positive pressure in the apparatus and thus prevent boiling of the solution. The temperature of the apparatus and its contents was brought t o 35" * 0.05" C. in a water bath, the central stopcock was closed, and the upper stopcock was removed. The solution that had expanded into the portion of the apparatus above the central stopcock was carefully removed, and the apparatus n-as reassembled and yeighed. From the net weight of solution and the known volume of the pycnometric bulb, the density of the solution was calculated.
TABLE 111. TOTAL AND PARTIAL PRESSURES IN XHJJO3-NH3-HzO AT 10" C. Corn n of SOln., % NHs NHiNOa 0 lo 22.4 44.9 15 0 21.2 42.4 20 0 19.9 39.9 25 0 18.7 37.4 30 0 17.4 34.9
kt.
NHa in Gas Phase, Vol. yo 89.4 92.0 94.2 94.0 95.5 96.8 96.4 97.4 98.2 98.0 98.6 99.1 99.0 99.4 99.7
THE
SYSTEM
A study of the results obtained by analysis of the vapor phase showed that the ratio of the lveight percentage, x, of ammonia in solution to the volume percentage, y, of ammonia in the vapor phase in equilibrium with the solution bore a straight-line relation to the \%-eightpercentage of ammonia in solution, both for the ternary compositions and for t,he ammonia-water solutions. Hence, by the method of least squares, it was possible to develop equations of the form, x/y = A
+ BX
by means of which the composition of the vapor phase could br interpolated from the measured values. Table I gives derived values for constants A and B. These equations fitted the experimental data with an accuracy of *0.60/, ammonia in t,he vapor phase. Tables I1 and 111 present interpolated values for the total vapor pressures and for the partial pressures of ammonia and water a t 10" and 35' C. The measurements of total pressures from which these data were derived were made with a prccision of =t1 mm. The tabulated data for the partial pressures generally are rounded to three figures for ammonia and to two figures for watel. The total pressures in Tables I1 and 111 for the system ammonium nitrate-ammonia-water agree closely with the data of Kracek ( 4 ) and of Perman ( 6 ) for the binary system ammonia-ivater. The tabulated partial pressures of ammonia for the binary system arc within experimental error of the values obtained by Perman ( 7 ) a t 10" C. At 35' C. Perman's partial pressures for ammonia generally are higher than t,hose obtained in the present work. Perman's values for total pressures by addition of the two partial pressures generally were higher, however, than the corresponding values he obtained by- an independent method. Densities of the solutions a t 35" C. are given in the last column of Table 11. The measurements from which the data for the ternary system were interpolated were made with a precision of +0.001 gram per cc. The densities given for the system ammonia-water were extrapolated from data of International Critical Tables (5)and of Nittasch, Kuss, and Schlueter ( 5 ) . The tabulated densities for the ternary system are in good agreement with values interpolated from the data of Adams and Gibson ( 1 ) and of Arbo-Hoeg ( 2 ) for ammonium nitrate-u.ater solutions. LITERATURE CITED
(1) Adams, L. H., and Gibson, R. E., J . A m . Chem. Soc., 54, 4520-
36 (1932). ( 2 ) Arbo-Hoeg, F. M., 2. anal. Chem., 81, 114-16 (1930). (3) International Critical Tables, Vol. 111,p. 59 (1928). (4) Kracek, F. C., J . Phys. Chem., 34,499-521 (1930). ( 5 ) Mittasch, A., Kuss, E., and Schlueter, H., 2. anorg. allgem Chem., 159, 1-36 (1926). (6) Perman, E. P., J . Chem. Soc., 79, 718-29 (1901). (7) Ibid., 83, 1168-83 (1903). (8) Porter, F., Bardwell, D. C., and Lind, S. C., IND.EN@. CHEM..
18, 1086-7 (1926). (9) U. S. Army Specification 50-11-59D, Feb. 6, 1942.
Vapor Pressure, Mm. H g Partial Partial of NHa of He0
Total 54.5 68.5 82.0 92.5 112 137 150 173 215 230 264 321 349 388 446
48.7 63.0 77.0 87.0 107 133 145 169 211 225 260 318 345 386 445
5.8 5.5 4.8 5.5 5.0 4.4 5.4 4.5 3.9 4.6 3.7 2.9 3.5 2.3 1.3
Pure Hydrocarbons from PetroleumCorrection I n the January, 1946, issue, this paper by Griswold, Andres, Van Berg, and Kasch had an unfortunate error in the Literature Cited on page 70. Authorship of four articles (11) from a symposium on aaeotropic and extractive distillation is erroneously ascribed t o Happel, Correll, Eastman, Fowle, Porter, and Schutte. The writers of the papers in question are R. R. White, H. G. Drickamer, G. G. Brown, H. H. Hummel, C. L. Dunn, R. W. LIiller, G. J. Pierotti, R. X. Shiras, and M o t t Souders, Jr.
