Solubility of Hydrogen in Water at 25" C. from 25 to 1000 Atmospheres R. WIEBE, V. L. GADDY, AND CONRADHEIIVS, JH. Fertilizer and Fixed Nitrogen Investigations, Bureau of Chemistry and Soils, Washington, D. C. W O papers on the solubility Of gases at high
T
which indicate have appeared h e inrecently,pressures terest attached t o the subject. Goodman and Krase (6) measured thesolubilityof nitrogenin water u p to 300 a t m o s p h e r e s over a wide range of temperature, while Frolich and collaborators (6)obtained the solubility of hydrogen, nitrogen, and methane in water and other solvents at 250 c* to approxi-
atmospheres'
The
The solubility of hydrogen in water at 25" C. and from 125 to 1000 atmospheres has been measured in a simple bubbling-type apparatus. Equilibrium is approached from both sides. W h e n the pressure of hydrogen is 1000 atmospheres, water at 25" C. absorbs 15.20 CC. of gas (8. T. p.) per gramof as against 0.0178 cC. when the partial pressure of hydrogen is 1 atmosphere. The experimental accuracy is estimated to be about 0.5per cent except at the lower pressures. .4solubility apparatus, provided with a n externally driven stirrer used by Tremearne in some preliminary work, is also described.
knowledge of the solubility of hydrogen and nitrogen in water is valuable in the operations leading to the synthesis of ammonia and in other related high-pressure processes. With the exception of the work of Frolich and collaborators (j), all published work on hydrogen has been done at relatively low pressures. Tremearne, of this laboratory, using an apparatus to be described later, first attempted to rneasure the solubility of hydrogen in water up t o 1000 atmospheres (8). However, owing t o mechanical difficulties and to the time it would have required to establish equilibrium, his work was discontinued and the present method adopted. APPARATUSAND EXPERIMENTAL PROCEDIJRE The present apparatus and method are exceedingly simple. Figure 1 shows the steel cylinder in which the high-pressure saturation was effected. It is silver plated on the inside and has a capacity of 275 cc. of water, For initial saturation, hydrogen a t a pressure from 10 t o 60 per cent higher than that to be finally required mas passed into the cylinder a t A , bubbled through the water. and expanded to the atmosphere through C and D ( B and E b e i n g closed). After several hours, samples were taken t o insure saturation above the finally desired value. At each pressure two approaches to equi63 5 tm librium were t h e n made. I n the first, which will be called the high-pressure approach, the pressure was simply dropped to its final value and h y d r o g e n bubbled through to aid in esFIGURE1. HIGH-PRESSURE APPARATUS t a bli s h i ng equilibFOR MEASURING SOLUBILITY OF GAS rium. In the other, IN WATER the low-pressure ap-
-
r 1
mn
823
~
~
~
rium value, and h y d r o g e n wm ~ ~ ~ ~ long to insure a gas content lower
; : ;ObC
~h,i~n~~n~q~l\,'~,';'e studied. After this period of des a t u r a t i o n , the p r e s s u r e was brought up to the finally desired value and gas bubbled through as ~
,",5",e$,,~~,","a.~fl1~~ ~ ~ ~ d
~
to stand a t rest 3 to 48 hours before the sample was taken. Ordinarily 2 hours were ample to insure equilibriumconditions. Asshown by the results, no real difference was found between the two approaches.
Figure 2 shows the buret for the measurement of samples. The high-pressure valve is identical with valve E in Figure 1. In the sampling procedure the high-pressure valve was opened slightly and a mixture of gas and water appeared. The water was measured in the 30-cc. buret, the bulk of the gas in the bulb volumenometer, and any amount smaller than 35 cc. in the 50-cc. gas buret. Measurements were made after no visible bubbles escaped from the water. The size of water samples r a n g e d from 11 to 29 cc. The temperature of the buret was kept at 25' C. All burets had been carefully calibrated with water. The hydrogen used was 99.8 per cent pure according to combustion analyses, the impurity being nitrogen. Pres8 u r e measurements were made on two p i s t o n gages described by B a r t l e t t and co-workers ( 2 ) . The gages were connected directly to the top of the solubility apparatus (connection not shown in Figure 1) in o r d e r to prevent any pressure drop in this line during saturation.
DISCUSSION OF RESULTS T h e experimental results are presented in Table I and F i g u r e 3. The values for the two to e q u i l i b r i u m
~
FIGURE2. BURETSYSTEMFOR SOLUBILITY OF GASESIN WATER
,
a24
Vol. 24, No. 7
INDUSTRIAL AND ENGINEERING CHEMISTRY
possibility of supersaturation of the water while in the buret was investigated. A 100 per cent supersaturation of the water in the buret for the 100-atmosphere run would produce an error of 1 per cent. That this was not anywhere near the case has been quite definitely established by taking samples a t different partial pressures of hydrogen from 500 to 726 mm. in the buret, by evacuating the water initially in the buret and by varying the initial volume of water. The turbulence of the outcoming sample must effectively prevent supersaturation.
TABLE I. ABSORPTION COEFFICIENTS FOR WATERAT 25 * 0.1' C.
OF HYDROGEX AT VARIOUS FIGURE 3. SOLUBILITY PRESSURES
(In 00. of gas at 9. T. P. per gram of water) VALUES VALUES FOR LOWFOB HIQHPRES- PRESSURE PR E8BuR E SURE APPROACHAVERAGE APPROACH AVERAGE 25
=
0.674
d,f) -
50
of the average value. It will be noticed that the probable error so calculated is in some instances considerably smaller than the difference between the two average values, thus indicating the fact that reproducible values can be obtained a t any point in the neighborhood of the particular equilibrium value when the process of saturation is dependent solely on diffusion from the surface of the liquid. A practical coincidence of the two average values could be obtained if more time had been taken in the establishment of equilibrium. The error of the final values was calculated from the average of the two average values, and a consideration of a possible effect of pressure f l u c t u a t i o n a n d o t h e r experimental u n c e rtainties. T h e m a x i m u m possible error due to measurements of water and gas volumes, and due to pressure and temperature fluctuations is estimated to be about 2 per cent a t the lowest pressures and 1 per cent in the range from 200 to 1000 atmospheres. The e x p e r i m e n t a l r e s u l t s show that only in a few isolated cases was this possible maximum reached.' C o n s i d e r a t i o n was also given to the following points: During final saturation the p r e s s u r e of the gas on the FIGURE 4. TWINBOTTLE FOR s u r f a c e of the liquid was VAPOR-PRESSURE AND SOLUa BILITY WORK AT HIGH c t u a l l y 20 m m . of mercurv" higher PRESSURES - than indicated by the gage, owing to the column of water in the cylinder. Except a t the very lowest pressure, the correction for this is negligible, even if all the gas were assumed to remain in the liquid. The 1 I n a later paper it will be shown that a shaking method, devised by R. Wiebe and T. H. Tremearne, yields values which are in agreement, within 0.1per cent, with those obtained by means of the bubbling apparatus used here.
FINAL VALUES
Atm
are tabulated separately. The agreement between the two sets of measurements a t any pressure is satisfactory. In the average columns, the error stated is the probable error as given by equation
E
HYDROQEN IN
..
..
..
00
..
.. ..
.. ..
.. ..
.. 200
... ...
...
...
... 400
... I
.
.
... ... ... ... ... ... ... . .
. . ... ... ...
...
... ... ...
... ...
600
... ...
... ...
0.440 .... 0.431 .... .... 0.432 . . . 0.436 0.438 0.438 0.430 %O.OOl
0.440 0.433 0.432 0.436 0.432 0.438 ... .... 0.435 , . . .... 0.435 . . . . . 0.440 ... . . . 0.433 ... .... 0.437 0.872 0.869 0.864 0.868 0.873 0.866 0.865 0.863 0.872 0.870 0.860 0.860 0.868 0.862 .... 0.875 0.867 . . . 0.866 0.864 0.859 0.863 0.866 0.865 %O.OOl 0.876 0.869 ... 0.874 ... 1.728 1,729 1.729 1.723 1.733 1.730 1.731 .... 1.733 1.730 1.723 1.729 1.726'2 0.001 1.735 1.732 .... ... 1.728 . . 1.727 ... 1.726 . . 1.728 .., 1.730 ... 1.736 .... ... 1.732 . . . . ... 3.402 .... 3.386 3.393 3.381 3.401 3.380 3.399 3.373 3.400 3.378 3.377 3.399 3.396 3.390 3.414 3.401 3.397 .... 3.388 3.385 .... 3.389 3.410 3.387 3.382 3.386%0.002 3.408 3.397 3.404 3.400 6.56 6.55 .... 6.59 .... 6.58 6.58 6.57 .... 6.57 6.56 .... 6.56 .... 6.57 6.56 6.56 .... 6.57 6.56 6.56 6.57 ... . . . 6.56 ... .. , 6.56 . . .... . . .... 6.56 6.56 ... . . . 6.56 6.58 6.55 6.56 6.57 ... .... 6.60 ... .... 6.57 .... 6.56 ... .... 6.57 ... .... 6.56 ... .... 9.56 9.57 9.59 9.59 .... 9.57 9.57 .... 9.58 9.59 .... 9.58 9.56 .... I
.
.... . . . .... .... ....
....
.... .... 0.436 'i'0.001 0.436'2 0.008
.... ....
.... ....
....
....
....
.... .... .... ....
....
....
.... .... .... .... ....
0.868 'i'0.001 0.867 '20.012
.. .... .... ....
....
....
.... ....
.... ....
....
.... ....
....
....
.... ....
.... ....
1.730 '20.001 1.728 ' g 0 .017
....
....
. . . . .... . .
.... .... .... .... .... ....
. . ..
.... .... .... ....
....
....
. . .
3.399%0.002
.... ....
3.39'20.03
....
.... .... .... .... .... .... .... .... . . .
....
. . . .... . . . ....
.... ... .... ....
.
....
.... .... .... ....
....
....
6.57
6.57 2'0.04
.... .... .... ....
....
....
....
.... .... ....
July, 1932
INDUSTRIAL AND ENGINEERING CHEMISTRY
T A B LI.~ ABSORPTIONCOEFFICIENTS FOR HYDROGEN IN WATERAT 25 A 0.1 ’ C. (Continued) (In (10. of gaa at S. T. P. per gram of water) VALUES VALUES FOR HIGHPRES- PRESSURE PRESSURE BURE APPROACH AVERAGE APPROACH AVERAGE FOR LOW-
FINAL
Atm.
800
1000
9,58
9.59 9.55 9.58 9.59 12 46 12.48 12 44 12.48 12.45 12 46 .... 12.48 12 45 12.46 12 45 12 46 12.50 12.45 12.43 12.48 12.42 12.47 12.46 12.48 15.19 15 13 15.38 15 07 15.25 15 16 15.15 15 20 15.28 15 18 15.27 15.13 15.10 15 20 15.29 15 20 15.23 15 14 15.37 15 16 15 19 15 16 1 0 01 15.23 15.26 15.14 15.23 15.23 15.30 15.11 15.16 15.20 15.24 15.31 15.20 15.23 15.26 .... 15.18
9 60
9’58
9.58‘1’0.05
....
. . , . .. 12:47
12.46‘20.06
825
steel plate D, to which the stirrer blades were attached. The steel plate, D, was forced upward against the ball bearings as indicated. The packing, consisting of shredded lead and flax, was adjusted by means of gland G. Since the space between the shaft and the stirrer guide was filled with water, the gas did not come in direct contact with the packing, and thus the leakage was kept down greatly, though it was impossible to keep the pressure constant overnight, which necessitated resaturation and gave no time for internal adjustment. Another mechanical difficulty was the twisting off of the stirrer shaft at the steel plate. In all runs, equilibrium was approached only from the lower side, and saturation was attempted solely from the surface through stirring. The necessarily slow rate of stirring and the great depth of the liquid made saturation extremely slow. I n Table I1 a comparison is made between the results obtained by Tremearne (8)’those of Frolich and collaborators (S), the experimental values obtained in the present work, and the ones calculated from Equation 1. FROM SEVER.4L TABLE 11. COMPARISON OF RESULTS SOURCES
( I n cc. of gas at S. T. P. per gram of water)
FROLICH
PRESSURE Atm.
25 50 100
15.23‘1’0.01
15 .20 ‘GO.08
The increase of the volume of water due to solubility of hydrogen in water a t 1 atmosphere has been shown to be negligibly small by Angstrom (1) as far as the present work is concerned. A slight error might possibly arise from the fact that there was a concentration gradient in the water of the gas burets. This effect, which would have been most noticeable in the first sample taken, was not observed. Drucker and Moles (4) give as the average of the compilation of the “best” results for the Bunsen absorption coefficient 0.0178, which also agrees with the average obtained from the different K values in the International Critical Tables (7). Since the individual values for the Bunsen absorption coefficient a t 1 atmosphere vary from 0.0175 to 0.0182, the average value is rather uncertain. Roughly, the present results would seem to favor the lower value, 0.0175, which was obtained by Winkler (9). Cassuto ( 3 ) obtained 0.150 for the Bunsen coefficient a t 10 atmospheres. Since the value comparable to his obtained in the present work a t 25 atmospheres is 0.0174, Cassuto’s values must be too low, unless it is assumed that the solubility goes through a decided minimum below 25 atmospheres. The following equation:
TREXEARIE
AND WIEBE CO-WORKERS GADDY’,
(8)O
(6:b
HEIXS
CALCD. FROM
EQ. 1
......
0.436 ..... 0’66 0.867 0:876 1.64, 1.65; 1.67 .... 1:iz 1.68, 1.68, 1.53, 1.74 1.728 i:iii 200 .... 3.17, 3.24, 3.25 ... 3.39 3.13,3.24 3.3i 300 .... 4.50,4.94, 4.74,4.82,4.85 4.98 . . . 4.55,4.58,4.68 ... 400 .... 5.74,6.54 6.57 5.20,6.11, 6.08,6.54 6:56 .... 5 94 6.28,6.39, 6.21 .. ROO .... 9:Sl: 9.52,8.81,9.14,9.46 9.58 8.60,9.76 9:iY ... ... 8.50. 9.46 800 11.90, 12.28 10.97, 11.31, 11.75 12.46 12147 1000 13.86 13.28, 13.11, 14.22 .. 15:zO ii:ig Values given in this column were from consecutive runs of a series including the highest obtained. The runs were selected from a total of over 500. The other results either form a gradually ascending series or are irregular and for the most part considerably lower. At 1000 atmospheres the shaft twisted off several times, and final results could never be obtained. b These values can be only approximate since they were taken from a blueprint which Frolich had kindly sent the authors.
As shown by the results of the present work, Tremearne did not succeed in reaching saturation except for isolated values. It was therefore impossible to give average values, and the above form was adopted. ACKNOWLEDGMENT
The authors wish to express thanks to W. Edwards Deming, of this laboratory, who kindly derived Equation 1 for them, and to T. H. Tremearne who permitted them to include a discussion of his work. LITERATURE CITED
Tremearne’s apparatus, as shown in Figure 4, consisted of two internally connected cylinders drilled in one block.
(1) Angstrom, Ann. Physik Chem. (Wiedemann), 15, 297 (1882). (2) Bartlett, Cupples, a n d Tremearne, J . Am. Chem. SOC.,50, 1275 (1928). (3) Cassuto, Physik. Z.,5 , 2 3 3 (1904); International Critical Tables, Vol. 111, p. 256, McGraw-Hill, 1926. (4) Drucker a n d Moles, 2. physik. Chem., 75, 405 (1911). (5) Frolich, Tauch, Hogan, a n d Peer, IND.ENQ. CHEX, 23, 548 (1931). (6) Goodman and Krase. Ibid., 23,401 (1931). (7) International Critical Tables, Vol. 111, p. 256, McGraw-Hill, 1926. (8) Tremearne, T. H., Laboratory Rept. on “ T h e Solubility of Hydrogen in Water a t 25’ C. a n d a t Pressures from 100 t o 1000 Atmospheres,” Fertilizer and Fixed Nitrogen Investigations, Bur. Chem. a n d Soils, June, 1931. (9) Winkler, Ber., 24, 89 (1891).
Two externally driven stirrers provided agitation. The gas entered at A , and samples were taken at B. A hardened steel shaft, C, rotating in guide E , was at its lower end threaded into
RECEIYED January 26, 1932. Presented before the Division of Phyaioal and Inorganic Chemistry at the 82nd Meeting of the American Chemical Society, Buffalo, N. Y.,August 31 to September 4, 1931.
+
S = 0.0244 0.01712 p - 0.00000196 p 2 (1) = number of cc. of gas (S. T. P.)dissolved in 1 gram of water p = partial pressure of hydrogen
where S
fits the data from 50 to 1000 atmospheres within the estimated error but gives impossibly high values a t lower pressures.
METHODAKD RESULTS OF TREMEARNE
