10
W I L L I h 3 I R. JICJIILL.iS A S D HVGH J. MCDOSALD
T--\POR PRESSGRE O F THE T E R S 1 R Y SI-STElI LICETIC -4CIDBESZESE-C'hRBOS TETR.-ICHLORIDE WILLIAM R . lIclIILL.iS1
AXD
HCGH J . lIcDOS.1LD
D e p a r t m e n t of Chetnistl.!/. IIIi/jois I / i s t i t : i t c of Tech t l n l o y y , C h i c a g o . I/liuoi.s
R e c e i w l J r i l y 10, 1944 Rerised c o p : r c c e i i d September f 8 , f -9.f.$
In continuation of the program of this laboratory in the study of liquid mistures, the vapor pressure of the system acetic acid-benzene-carbon tetrachloride vas investigated. The analytical data on the materials used in this study and the details of analysis hare been discussed in a previous paper (1). 1PP.IRAITTB .1SD P R O C E D U R E
The apparatus used is .shown in figure 1. -1250-cc. boiling flask jras fitted with a side arm for a thermometer. Standard-taper ground-glass fittings irere used. An ice-jacketed condenser gave efficient reflux, as shown by t,he fact that after several hours of use with many samples, only about 0.5 ml. was caught in the vapor trap. -1hydrochloric acid-ice bat'h kept this trap at about' - 16°C. The manometer was carefully made and heated so as t'o expel any air vhich might be dissolved in the mercury or adsorbed on the surface of the glass. -\ir n-as admitted to the system by means of a regular stopcock. L% calciuni chloride tube extracted the greater part of the moisture from the air before it reached the pump. ICenco Hyvac (n-ith a slight change in design) n-as used for lowering the pressure in the system. Because of the large yolunie of air being pumped through the oil, some of it n-as splashed onto the under side of t'he plat'e covering the pump mechanism and x i s blown out in the form of a fine spray. To remedy this, a neTT plate was constructed n-ith n &in. length of $-in. pipe in the center and flush n-ith the under side of the plate. This outlet was large and long enough to prevent oil spray or bubbles from being blon-n out into t'he air. large test tube inverted over the pipe prevented foreign matter from falling into the pump mechanism. The use of a stopcock allowed the pressure to lie set at the desired point u-ith ease. A1ftera few seconds, equilibrium was attained b e t w e n the boiling liquid and its yapor. After a fen- minutes, the readings of presrure and temperature were made. The manometer 11.3s,shut off and the temperature of the boiling liquid read simultaneously. The pressure could t.hen he read at leisure n-ith the cat hetometer. Superheating \vas aI-oided by the use of boiling chip-:. -1slow leak immer.sed in the boiling liquid also prel-ented superheating hut cnrried over so much vapor that it n-as abandoned. The effects of superheating l~ecnmenoticeable at pressures lon-er t'han one-third of :in atmosphere. The apparatus and esperiniental technique u-ere tested by determining the hiling points of carbon tetrachloride at several different pressures. The x-aporA \
1
Present address: IIine Safety .ippliaiicee Co., Pittsburgh. Peniisylvania.
STBTE?J .LCETIC .\CID-BESZESE-CARBOS
TETR i CHLORIDE
11
pressure values so obtained checked the licit T-alues reported in the literature within :ibout 0.3 per cent, and Tvere reproducible. In the case of the threecomponc~nt$:\.stein the accuracy as limited. not l y the pre.-iure meawremen; n-hich, in fact, \vas measured to a greater dcgree of accurcicy than justified, hut L)y the temperature measurement, \vhich n-as read t o somen-hat better than one-tenth of a degree. The boiling point of each sample I R I ~determined t h e e t iines under different prtwures. One determination m i . : made :it n b o u ~atmospheric pressure, one a t
FIG.1. Apparatus for determining boiling points under reduced pressure
a pressure about 10 cm. lon-er, and one at a pressure about 20 or 30 em. lon-er. Three points were plotted for each sample, pressure against teniperat.ure. The smooth curyes dran-n through t,he experiment a1 points n-ere estrapolated graphically so as t,o intersect t!ie line representing 760 iiini. pressure and the line representing a temperature of GO.OcC. In the Srst. case, the boiling points of the system under normal atmo;pheric pressure Twre obtained. I n the second c c i s ~ ,the T-apor pressures at G O T . n-ere obtained. These n-ere piot'ted as isotlierms rind as isobars on the three-component tliqrarn (see figure 2 and figure 3 ) . I n the graphical extrapolation the accuracy niust necessarily have been reduced somei.i-hat,, from 0.3 to about @.4per cent. The xormal lioiling points and the vapor pressures at' 60°C. are: therefore. not to lie interpreted as lleing more
Carbon t 8 t raohlor i d e
Acetic aoid
Benzena
FIG. 2 . Lines of constant-boiling point under armospheric pressure for the terfiary system,
Carbon t e t raohlo ride
Aoeth
Benzene
aold FIG.3. Lines of constant vapor pressure at 60'C; for the ternary system. Pressures are given in millimeters of mercury.
SYSTEM l C E T I C .\CID-BESZENE-CARBOS
13
TETRlCHLORIDE
T.4BLE 1 S'apor p r e s s u r e of the ternarg system h,acetic acid; B. benzene; C, carbon tetrachloride BOILISG TEMIPERXTTRE
WEICIIT P E R CENT OF PREI~LRE
A
B
0
0
100.
10
90.
C
~
IC.
nim. H J
72.0 59.5 36.0 77.2* 60.0*
643.20 398.85 170.95 760.00 415.00
74.0 60.5 43.0 76.8 60.0
677.10 413.30 213.35 760.00 410.00
11.6
79.0 60.5 38.5 80.1 60.0
724.65 3i6.40 161.20 760.00 370.00
22.0
80.6 66.6 42.4 82.9 60.0
68s. 90 424.30 171.65 760.00 338.00
31.6
74.5 64.0 54.0 76.4 60.0
i03.35 480.75 336.80 760.00 417.00
0
78.0 70.0 54.0 80.2 60.0
717.70 5 4 i . 05 306.95 760.00 398.00
20.5
82.5 72.5 60.0 83.5 60.0
534.00 528.10 338.45 760.00 338.45
35.0
88.0 77.0 56.0 90.4 60.0
704.50 488.80 229.20 760.00 273.00
3.0
1.4
TVILLI.131 E . .If c'JIILL.IS A S D HUGH J. McDOSALD
TABLE l - - C l ~ n t i / ~ ~ ~ d '
S.4:dPLL
WEIGHT PEP. CENT OF
BOILISG IEVPLRATrRE
-~
PRESXRL
B
.i
.. .
'i
9
ll!!l:,
71.6 65.5 5i.0 I I .3
--
60.0 10
1
s1 60 59 83 60
~
1
2 1 8 7 0
1
59 6 60 0
'
1
65 25 10 00 00
20.0
C
(5-1 6
64.2 91 2 bo 0
715 7 5 -1% 40 2b2 95 760 00 255 00
13
76.8 69.6 58.8 78.7 60.0
7lb.25 575.20 388.70 760.00 410.00
0
14
81 . ?
732.30 539.20 304.25 760.00 353.00
31 . 0
71.8 61.0 82.6 60.0
15
54.5 76.6 59.8 86 0 ti9.0
727.10 563.50 314.05 760.00 318.00
44.6
16
Sb.5 70.5 61.0 89.7 60.0
731.80 394.95 386.55 760.00 277. 00
58.5
12
.io 0
81.0
80.0
34 0
1'3
S7 0 ia 5 61 0
,
i
707 50 505 05 286 50 760.00 270 00
11
c
I
693.95 512.75 377.05 760.00 423.00 713 499 316 760 351
--
iig
I
5
1
1 29.4
70.6
SYSTEM ACETIC .~CID-BESZESE--C.iE90S
13
TETR.\CHLQRIDE
TABLE 1-Continued I g,~PLE
I,
SC.
17
-i0.s 69.4 59.5 78.0 60.0
1s
8;
0
724.93
3S.S
510. SO 307. 45 760.00
330.00 721.20 423.70 235.15 760.00
51.6
265.00
60.0
730.TO 613.15 424.80 i60,OO 402.00
25
79.2 73.7 53.5 81.2 60.0
716.50 603.95 291.40 760.00 376 .OO
21.4
33
81 .O il.4 5i.O 84.1 60.0
706.25
36.0
21
24
7i.0 72.0 61.5 78.0
N.0 i3.5 60.5 86.6 60.0
60.0
760.00 413.00
72.0 5S.5
s5.0
1
40-L . i0
S"1
60.4 60.0 S6.S 60.0
40.0
570.03
27.0
83.4 60.0 20
)tjl%'.
769. 30
721. s5 523 . 00 353.45 760.00 3G5.00
79.0 70.0 59.0 80.6
60.0 19
Xi'LIGSY F E B CEXI qF
BOILING TEJIPER.ATCRE
0
511.90
295.65 i60.00 335.00 701.25 493.55 303.85 760.00 2%. 00
53.0
49.0
51.0
16
WILLIAM R . MChlILLAN -4SD HUGH J. MCDOSALD
TABLE 1-Continued WEIGHT PER CENT OF
BOILING TEMPERATURE
PRESSURE
"C.
?nm. Hg
25
78.0 72.2 58.8 79.0 60.0
26
SAhIPLE
A
B
C
732.95 595.60 376.40 760.00 393.00
0
59.5
40.5
79.8 71.0 55.5 80.8 60.0
734.20 550.30 308.90 760.00 360.00
19.6
27
85.0 71.0 59.5 86.6 60.0
733.10 488.50 307.80 760.00 315.00
43.2
28
86.7 70.0 59.0 86.8 60.0
730.05 415.65 281.65 760.00 295.00
53.0
29
79.0 72.0 58.9 80.0 60.0
731.10 579.30
0
70.0
30.0
30
80.0 71.3 58.0 81.0 60.0
734.10 556.90 337.05 760.00 369.00
15.7
31
83.0 72.1 61.0 84.0 60.0
736.15 504.10 340.60 760.00 330.00
36.5
32
86.0 71.8 59.0 87.0 60.0
736.90 458.85 280.55 760.00 295.00
52.0
760.00
I
SYSTEM ACETIC 1CID-BESZEh-E-C.kRBOS
17
TETR-ACHLORIDE
TABLE 1-Continued I
"lJPLE
1
EOILINC TEXPERATURE
WEIGHT PER C E S T OF PBESSURE
.i
B
0
7i.5
32.5
89.5
10.5
:i.
mm.l i s
79.3 70.0 5s.o 80.4 60.0
735.05 537.30 353.75
34
81.3 71.O 59.2 82.1 60.0
736.35 524.90 347.10 i60.00 358.00
22.7
3.5
s2.s 70.0 60.0 83.5 60.0
736.30 471.40 323.70 760.00 323.70
37.6
36
86.6 71.5 60.0 8i.5 60.0
736.45 434..55 286.60 760.00 286.60
53.0
37
79.4 70.0 60.5 80.3 60.0
732.65 522.65 373.35 760.00 368.00
0
38
80.9 70.1 58.5 E1.S 60.0
736.50 521 .a5 336.10 760.00 388.00
16.5
39
84.8 i0.9 57.5 85.4 60.0
i37.65 464.55 274.35 760.00 309.00
42.6
40
86.0 72.5 59.5 86.8 60.0
737.00 446.05 266.25 760.00 2i5.00
51.0
3:3
C
760.00
380.00
18
K I L L I A J I R. MCJIILLAN AXD HUGH J. R.ICDON.1LD
TABLE 1 (Continued) BQILISG TESIPEKATUKE
SAUPLE
"C.
PKESSURL
I
17?111.
.I
B
0
100.0
C
IIg ~
41
79.0 68.5 41.5 80.4 60.0
4'2 ~
'
80.0 71.5 43.0 82.5 60.0
723.90 507.75
1
I
I
1so.70
I
760.00 382.00
1
,
I
I
0
!
I
696.65 53-1.35 181.15 760.00 360.00
1
26 3 I
I I
~
I
43
,
1
82.5 76.0 57.4 85.0 60.0
84.8
44
73.0 59.4 87.4 60.0 107.5 91.5 79.0 118.5 60.0
45
46
602.95 564.50 279,10 760.00 316.00
~
45s
I
~
58.5
680.00 463.75 ?SO.40
~
I
i60.00 288.00
552
so
312.75 103.45 760 00 89.00
,
I
100 0
0
69.4
30.6
0
40.3
0
49.5
0
i
'
91.0 79.0 66.6 91.6 60.0
711 15 488 85 322.35 760.00 281.00
88 4 72.4 61.5 s9.3 60 0
735 65 129.40 294.50 760.00 279.00
59 7
56.2
739.00
50.5
I I
I
17
, ~
~
4s
l
.- I ELI
h\
A C E T I C A C I D - R E S Z C S C - C l R U O S TETRSCHLORIDE
1
1
60.5 85.4
70 8 58 6 s3.3 60 0
I
245 45 760 00 13s 00
100.6 60 0
‘
19
I
I
1
311.25 760 00
4% 326 760 344
65 15 00 00
I
~
The last tn-o of the fire values of temperature and pressure, for every sample, n‘ere obt niiied by extrapolation. ic
accurate than about 0.4 per cent. It is believed, however, that such data are of sufficient interest to be included in the tabulation of data. I n table 1 the last two readings of temperature and pressure Jyere obtained by extrapolation. The solutions to be tested n-ere made up in the folloning manner: Solutions were niade of the binary system carbon tetrachloride and benzene a t the approxmate 10 per cent divisions. These solutions were then each treated in the same manner. First the vapor pressures a t three different temperatures were determined, and a small sample 71-ithdrann for analysis by refractive index. Acid n-as added tn-o more times, and the same routine follon-ed each time. To clarify the method of preparing and recording the saniples of a given composition, conRider
