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The excess volumes for triethylamine + water
M-9580 J. Chem. Thermodynamics1979, 11,905-906
Notes The excess volumes
for triethylamine
+ water
T. M. LETCHER and W. SPITERI Departmentof Chemistry,University of the Witwatersrand, Johannesburg,South Africa (Received22 August 1978)
As part of our work in determining excess volumes for xC,H,,N+ (1 -x)H,O at temperatures very close to the critical temperature and in the region of the critical composition we have also measured the excess volumes over the whole composition range at three temperatures below the critical temperature. Triethylamine was twice distilled over NaOH in a 2 m distillation column under an atmosphere of nitrogen. The middle fractions of each distillation were collected and mixed together because different batches, although considered identical, were found to give slightly different excess-volume curves. Finally, the triethylamine was distilled using a spinning-band distillation apparatus. Again the middle fractions were collected together before degassing and mixing. The triethylamine was always kept under an atmosphere of nitrogen and in contact with mercury. Batches of 30 cm3 samples were degassed by successive freezing, evacuation, and thawing. In all cases identical degassing procedures were followed as we felt that differences in procedures led to variations in excess volume. The triethylamine was then sealed in tubes fitted with Rotaflow stopcocks. Freshly distilled mercury was added to equalize the pressures inside and outside the tubes, which were then stored. De-ionized and distilled water was degassed and stored before use in the same way as the triethylamine. The dilatometer, water bath, and temperature measuring equipment have been described.(l) Temperature control was improved and the temperature was constant to within +O.OOl K for the duration of a run. The density of triethylamine was determined in the range 274 K to 294 K using pyknometers. (‘) These results, together with reliable results for water, were fitted to the polynomials : P(C~H~~N, T)/g cme3 = 0.74606-0.922 x 10e3(T/K-273.15), p(HzO, 7)/g cme3 = 1.00033-8.35 x 10-6(7’/K-273.15) -4.90 x lO+(T/K-273.15)‘. 0021-9614/79/090905-l-02 $01.00/O 0 1979 Academic PressInc.
(1) (2) (London)
Ltd.
NOTES
906 TABLE
1. Molar excess volumes Vi for xCBH16N + (1 - x)HaO at various temperatures and the deviations 6 Vg calculated from equation (3) and table 2
v:
x
cm” mol-1
0.0295 0.0811 0.1425 0.1681 0.2004 0.2855 0.3178
-0.4594 -1.0820 -1.6099 - 1.7748 -1.9515 -2.2677 -2.3567
0.0415 0.0962 0.1519 0.1835 0.2506 0.3154
-0.6621 -1.3148 -1.7864 -1.9882 -2.3047 -2.5029
0.0593 0.1156 0.1632 0.2446 0.3157 0.3670
-0.9346 -1.5621 -1.9489 -2.3900 -2.6279 - 2.7284
104sv: cm3 mol-l -12 f33 +
+3
+1 f5 -10 +7 -31 $31
x
0.3884 0.4517 0.4944 0.5406 0.6158 0.6215 0.6734 0.3619 0.4567 0.4833 0.5115 0.5614 0.6042 0.4152 0.4438 0.4742 0.5122 0.5367 0.5841
E cm”mol-l 291.15 K -2.4766 -2.5380 -2.5380 -2.5197 -2.3946 -2.3879 -2.2247 283.15 K -2.5988 -2.6932 -2.6971 -2.6880 -2.6426 -2.5608 275.07 K -2.7952 -2.8083 -2.8196 -2.8026 -2.7862 -2.7083
ro*svg cm3 mol-1
+I6 -48 $14 -46 +14 -54 f29 -3
-i-2 -4 -2 +19 -28 +33 -16
+26
-24 +26
x
v: cm3 molpl
lO%VE, cm3 mole1
0.7255 0.7714 0.8362 0.9036 0.9265 0.9551
-2.0100 -1.7698 -1.3426 -0.8231 - 0.6243 -0.3878
+15 -10 +33 -15
0.7008 0.7615 0.8015 0.9093 0.9447
-2.2465 - 1.9308 -1.6736 -0.8262 -0.5064
-28
0.6215 0.6950 0.7732 0.8515 0.9122 0.9386
-2.6246 -2.3523 -1.9344 -1.3576 -0.8355 -0.5858
+52 -30
-t*;: -15 -l-4 -25 -f-5 -35
4-24
-27 +13
The excessvolumes are reproduced in table 1. Also given in this table are the deviations SV’Z from the smoothing equation: Vz/cm3molW1=
x(1-~)$JA,(1-2x)‘: (3) r=O The coefficients A, are given in table 2 together with the standard deviation o(Va. TABLE
2. Parameters for equation (3) for xC~H~~N + (1 - x)HzO at various temperatures 2’
291.15 283.15 275.07
-10.1528 - 10.7726 -11.2478
-0.4990 -0.6838 -0.9019
-2.5429 -2.7726 -2.8508
de3
As
- mol-l cm3
-3.7548 -3.7761 -3.6479
0.004 0.002 0.003
The- only other excess volumes for this system were measured by Campbell and Lamc3) at 290.15 K by pyknometry. Our interpolated results at this temperature agree, in the worst case, to within 0.04 cm3 mol-I. The authors wish to thank the CSIR (S. Africa) and AECI for financial aid. REFERENCES 1. Letcher, T. M. J. Chem. Thermodynamics 1977,9, 661. 2, Letcher, T. M. J. Chem. Thermodynamics 1972,4, 159. 3. Campbell, A. N.; Lam, S. Y. Can. J. Chem. 1973,51,4005.
Notes The excess volumes
for triethylamine
+ water
T. M. LETCHER and W. SPITERI Departmentof Chemistry,University of the Witwatersrand, Johannesburg,South Africa (Received22 August 1978)
As part of our work in determining excess volumes for xC,H,,N+ (1 -x)H,O at temperatures very close to the critical temperature and in the region of the critical composition we have also measured the excess volumes over the whole composition range at three temperatures below the critical temperature. Triethylamine was twice distilled over NaOH in a 2 m distillation column under an atmosphere of nitrogen. The middle fractions of each distillation were collected and mixed together because different batches, although considered identical, were found to give slightly different excess-volume curves. Finally, the triethylamine was distilled using a spinning-band distillation apparatus. Again the middle fractions were collected together before degassing and mixing. The triethylamine was always kept under an atmosphere of nitrogen and in contact with mercury. Batches of 30 cm3 samples were degassed by successive freezing, evacuation, and thawing. In all cases identical degassing procedures were followed as we felt that differences in procedures led to variations in excess volume. The triethylamine was then sealed in tubes fitted with Rotaflow stopcocks. Freshly distilled mercury was added to equalize the pressures inside and outside the tubes, which were then stored. De-ionized and distilled water was degassed and stored before use in the same way as the triethylamine. The dilatometer, water bath, and temperature measuring equipment have been described.(l) Temperature control was improved and the temperature was constant to within +O.OOl K for the duration of a run. The density of triethylamine was determined in the range 274 K to 294 K using pyknometers. (‘) These results, together with reliable results for water, were fitted to the polynomials : P(C~H~~N, T)/g cme3 = 0.74606-0.922 x 10e3(T/K-273.15), p(HzO, 7)/g cme3 = 1.00033-8.35 x 10-6(7’/K-273.15) -4.90 x lO+(T/K-273.15)‘. 0021-9614/79/090905-l-02 $01.00/O 0 1979 Academic PressInc.
(1) (2) (London)
Ltd.
NOTES
906 TABLE
1. Molar excess volumes Vi for xCBH16N + (1 - x)HaO at various temperatures and the deviations 6 Vg calculated from equation (3) and table 2
v:
x
cm” mol-1
0.0295 0.0811 0.1425 0.1681 0.2004 0.2855 0.3178
-0.4594 -1.0820 -1.6099 - 1.7748 -1.9515 -2.2677 -2.3567
0.0415 0.0962 0.1519 0.1835 0.2506 0.3154
-0.6621 -1.3148 -1.7864 -1.9882 -2.3047 -2.5029
0.0593 0.1156 0.1632 0.2446 0.3157 0.3670
-0.9346 -1.5621 -1.9489 -2.3900 -2.6279 - 2.7284
104sv: cm3 mol-l -12 f33 +
+3
+1 f5 -10 +7 -31 $31
x
0.3884 0.4517 0.4944 0.5406 0.6158 0.6215 0.6734 0.3619 0.4567 0.4833 0.5115 0.5614 0.6042 0.4152 0.4438 0.4742 0.5122 0.5367 0.5841
E cm”mol-l 291.15 K -2.4766 -2.5380 -2.5380 -2.5197 -2.3946 -2.3879 -2.2247 283.15 K -2.5988 -2.6932 -2.6971 -2.6880 -2.6426 -2.5608 275.07 K -2.7952 -2.8083 -2.8196 -2.8026 -2.7862 -2.7083
ro*svg cm3 mol-1
+I6 -48 $14 -46 +14 -54 f29 -3
-i-2 -4 -2 +19 -28 +33 -16
+26
-24 +26
x
v: cm3 molpl
lO%VE, cm3 mole1
0.7255 0.7714 0.8362 0.9036 0.9265 0.9551
-2.0100 -1.7698 -1.3426 -0.8231 - 0.6243 -0.3878
+15 -10 +33 -15
0.7008 0.7615 0.8015 0.9093 0.9447
-2.2465 - 1.9308 -1.6736 -0.8262 -0.5064
-28
0.6215 0.6950 0.7732 0.8515 0.9122 0.9386
-2.6246 -2.3523 -1.9344 -1.3576 -0.8355 -0.5858
+52 -30
-t*;: -15 -l-4 -25 -f-5 -35
4-24
-27 +13
The excessvolumes are reproduced in table 1. Also given in this table are the deviations SV’Z from the smoothing equation: Vz/cm3molW1=
x(1-~)$JA,(1-2x)‘: (3) r=O The coefficients A, are given in table 2 together with the standard deviation o(Va. TABLE
2. Parameters for equation (3) for xC~H~~N + (1 - x)HzO at various temperatures 2’
291.15 283.15 275.07
-10.1528 - 10.7726 -11.2478
-0.4990 -0.6838 -0.9019
-2.5429 -2.7726 -2.8508
de3
As
- mol-l cm3
-3.7548 -3.7761 -3.6479
0.004 0.002 0.003
The- only other excess volumes for this system were measured by Campbell and Lamc3) at 290.15 K by pyknometry. Our interpolated results at this temperature agree, in the worst case, to within 0.04 cm3 mol-I. The authors wish to thank the CSIR (S. Africa) and AECI for financial aid. REFERENCES 1. Letcher, T. M. J. Chem. Thermodynamics 1977,9, 661. 2, Letcher, T. M. J. Chem. Thermodynamics 1972,4, 159. 3. Campbell, A. N.; Lam, S. Y. Can. J. Chem. 1973,51,4005.