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Excess molar enthalpies of (cis-9-octadecenoic acid + n-hexane or benzene or trichloroethene or tetrachloroethene) at 298.15 K
M-2385 J. Chem. Thermodynamics 1989, 21. 8 19-821
Excess molar enthalpies of (cis-S-octadecenoic acid + n-hexane benzene or trichloroethene or tetrachloroethene) at 298.15 K
or
C. YANES, P. PkREZ-TEJEDA, and A. MAESTRE Departamento de Quimica Fisica, Universidad de Sevilla, Prof: Garcia Gonzilez, s/n, 41012~Sevilla, Spain (Received 26 April 1989) The excessmolar enthalpies HE of {cis-9-octadecenoic (oleic) acid + n-hexane or benzene or tetrachloroethene or trichloroethene} have been determined as a function of mole fraction at atmospheric pressure and 298.15K. His are positive for the three first mixtures and negative for the last.
1. Introduction We have been interested in the study of the thermodynamic behaviour of vegetableoil components (fatty acids) in organic solvents. In a previous paper”’ the molar excessenthalpy HE of {cis-9-octadecenoic (oleic) acid + cyclohexane} at 298.15 K was presented. The present work extends the above studies to (oleic acid + n-hexane or benzene or trichloroethene or tetrachloroethene) at 298.15 K and atmospheric pressure. Some of these mixtures are of increasing scientific and practical interest because of their use in extraction processes.
2. Experimental The apparatus for the present study was essentially the same as that previously described.“’ The Calvet microcalorimeter was calibrated with (n-hexane + cyclohexane) at 298.15 under the same conditions as the mixtures to be studied and the calibration was checked by determining the excessmolar enthalpies of (benzene + cyclohexane). Our results differ by less than 1 per cent from those of the literature,(2m4’near x = 0.4. The calorimeter was thermostatted to +O.Ol K; mixing measurements were carried out at 298.15 K. The n-hexane was from Fluka (puriss., >99.5 moles per cent), and cyclohexane, benzene, trichloroethene, and tetrachloroethene were from Merck with purities of 99.5 moles per cent or greater. cis-9-Octadecenoic acid (oleic acid, C,,H,,O,) was CO21-9614/89/080819+03SO2.00/0
0 1989 Academic Press Limited
820
C. YANES,
P. PBREZ-TEJEDA,
TABLE [.u(cis-C,H,,CH:CHC,H,,CO,H)+(l
x
1. Excess molar enthaipy Hk for -.y)(C,H,, or C,H, or CCI,:CHCl
H"
HZ J.mol-’
j*i
’
AND A. MAESTRE
’
or CCl,:CCl,)1
Hi
A!L
J,mol-’
x
J.mol
’
at 298.15 K
Y
Hk J-mob ’
+(I -x)C,H,, 0.1403 0.2107 0.2641 0.2734
151 183 206 205
0.2786 0.2902 0.3061 0.3277
209 210 209 217
0.3470 0.3916 0.4087 0.4365
217 220 222 225
0.4652 0.473 1 0.5304 0.6225
218 221 215 187
0.7742 0.8646
126 85
0.1026 0.1372 0.1804 0.2286
177 239 297 352
0.2534 0.2904 0.3269 0.3361
381 393 392 395
+(l-x)C,H, 0.3624 0.3728 0.4127 0.4623
396 397 395 382
0.4901 0.5942 0.6569 0.7444
373 318 277 225
0.8217
154
0.0801 0.1083 0.1326 0.1532
-76 -116 - 123 - 127
0.2037 0.2690 0.2992 0.3634
- 141 -129 -115 -117
0.6050 0.7226 0.765 1 0.8464
0.0775 0.0984 0.1257 0.1340
22 29 30 33
0.1732 0.202 1 0.2446 0.3214
0.7925 0.8564
35 24
+(1 -x)C,HCl, -148 -158 -160 -157
41 44 53 63
0.439 1 0.5117 0.5565 0.5720
f(1 -x)C,Cl, 0.3418 0.3770 0.4573 0.5128
60 61 63 61
-104 -74 -62 -38 59 53 52 48
0.5461 0.6329 0.6872
the same as employed previously. (I) All liquids were used without purification.
further
3. Results and discussion The excessmolar enthalpies of {x(cis-C,H,,CH: CHC,H,,CO,H) + (1 -x&H,, or C6H, or Ccl, : CHCl or Ccl, : Ccl,) at 298.15 K are given in table 1 and figure 1. The measurements were fitted to the equation: Hz/(J.mol-‘)
= x(1-x)
t A,(1 -2x)‘-‘,
(1)
i=l
TABLE
2. Coefficients Ar of the fitting equation (1) for
.W,,H,,W+ (1-xLH,, (I--07% (1 - x)C,HCl, ( 1 - x)C,Cl,
868.436 1451.704 -521.436 245.408
284.125 858.421 -447.215 81.751
Hk at 298.15 K and standard deviations s
6.499 792.092 - 340.095 0.028
166.957 - 242.376 - 148.702 -40.333
427.478 - 1403.783 152.529 7.775
2 5 4 1
HE (cis-9-OCTADECENOIC ACID + ORGANIC LIQUID)
821
x FIGURE 1. Excess molar enthalpies Hk for {x(cis-9-C,H,,CH:CHC,H,,CO,H) + (1 -x) (C,H,, or C,H, or CCI,:CHCl or CCl,:CCI,)} at 298.15K: x, C 6H 14;0, C,H,; n , C&C: Ccl,; A, CI,C : CHCI; -, calculated from equation (1) with the coefficients from table 2.
by use of the unweighted least-squares method. The coefficients Ai and the standard deviations s are summarized in table 2. Curves calculated from equation (1) are also shown in figure 1; {s . (J . mol- ‘)/Hi(max.)} < 0.2 for mixtures containing chlorinated compounds and co.01 for the others, where HE(max.) denotes the maximum value of HE with respect to mole fraction. As shown in figure 1, HEs are positive over the whole composition range, with the exception of (oleic acid + trichloroethene) where an inversion of the sign of Hz was observed. These negative values indicate that interactions between oleic acid and trichloroethene overweight the contributions due to the breaking of interactions between like molecules. REFERENCES 1. Yanes, C.; Pellicer, J.; Rojas, E.; Zamora, M. J. Chem. Thermo&namics 1979, 1I. 177. 2. Lundberg, G. W. J. Chem. Eng. Data 1964, 9. 193. 3. Savini, C. G.; Winterhalter, D. R.; Kovach, L. H.; Van Ness, H. C. J. Chem. Eng. Data 1966, 11, 40. 4. Touhara. H.; Ikeda, M.: Nakanishi, K.; Watanabe, N. J. Chem. Thermodynamics 1975, 7, 887.
Excess molar enthalpies of (cis-S-octadecenoic acid + n-hexane benzene or trichloroethene or tetrachloroethene) at 298.15 K
or
C. YANES, P. PkREZ-TEJEDA, and A. MAESTRE Departamento de Quimica Fisica, Universidad de Sevilla, Prof: Garcia Gonzilez, s/n, 41012~Sevilla, Spain (Received 26 April 1989) The excessmolar enthalpies HE of {cis-9-octadecenoic (oleic) acid + n-hexane or benzene or tetrachloroethene or trichloroethene} have been determined as a function of mole fraction at atmospheric pressure and 298.15K. His are positive for the three first mixtures and negative for the last.
1. Introduction We have been interested in the study of the thermodynamic behaviour of vegetableoil components (fatty acids) in organic solvents. In a previous paper”’ the molar excessenthalpy HE of {cis-9-octadecenoic (oleic) acid + cyclohexane} at 298.15 K was presented. The present work extends the above studies to (oleic acid + n-hexane or benzene or trichloroethene or tetrachloroethene) at 298.15 K and atmospheric pressure. Some of these mixtures are of increasing scientific and practical interest because of their use in extraction processes.
2. Experimental The apparatus for the present study was essentially the same as that previously described.“’ The Calvet microcalorimeter was calibrated with (n-hexane + cyclohexane) at 298.15 under the same conditions as the mixtures to be studied and the calibration was checked by determining the excessmolar enthalpies of (benzene + cyclohexane). Our results differ by less than 1 per cent from those of the literature,(2m4’near x = 0.4. The calorimeter was thermostatted to +O.Ol K; mixing measurements were carried out at 298.15 K. The n-hexane was from Fluka (puriss., >99.5 moles per cent), and cyclohexane, benzene, trichloroethene, and tetrachloroethene were from Merck with purities of 99.5 moles per cent or greater. cis-9-Octadecenoic acid (oleic acid, C,,H,,O,) was CO21-9614/89/080819+03SO2.00/0
0 1989 Academic Press Limited
820
C. YANES,
P. PBREZ-TEJEDA,
TABLE [.u(cis-C,H,,CH:CHC,H,,CO,H)+(l
x
1. Excess molar enthaipy Hk for -.y)(C,H,, or C,H, or CCI,:CHCl
H"
HZ J.mol-’
j*i
’
AND A. MAESTRE
’
or CCl,:CCl,)1
Hi
A!L
J,mol-’
x
J.mol
’
at 298.15 K
Y
Hk J-mob ’
+(I -x)C,H,, 0.1403 0.2107 0.2641 0.2734
151 183 206 205
0.2786 0.2902 0.3061 0.3277
209 210 209 217
0.3470 0.3916 0.4087 0.4365
217 220 222 225
0.4652 0.473 1 0.5304 0.6225
218 221 215 187
0.7742 0.8646
126 85
0.1026 0.1372 0.1804 0.2286
177 239 297 352
0.2534 0.2904 0.3269 0.3361
381 393 392 395
+(l-x)C,H, 0.3624 0.3728 0.4127 0.4623
396 397 395 382
0.4901 0.5942 0.6569 0.7444
373 318 277 225
0.8217
154
0.0801 0.1083 0.1326 0.1532
-76 -116 - 123 - 127
0.2037 0.2690 0.2992 0.3634
- 141 -129 -115 -117
0.6050 0.7226 0.765 1 0.8464
0.0775 0.0984 0.1257 0.1340
22 29 30 33
0.1732 0.202 1 0.2446 0.3214
0.7925 0.8564
35 24
+(1 -x)C,HCl, -148 -158 -160 -157
41 44 53 63
0.439 1 0.5117 0.5565 0.5720
f(1 -x)C,Cl, 0.3418 0.3770 0.4573 0.5128
60 61 63 61
-104 -74 -62 -38 59 53 52 48
0.5461 0.6329 0.6872
the same as employed previously. (I) All liquids were used without purification.
further
3. Results and discussion The excessmolar enthalpies of {x(cis-C,H,,CH: CHC,H,,CO,H) + (1 -x&H,, or C6H, or Ccl, : CHCl or Ccl, : Ccl,) at 298.15 K are given in table 1 and figure 1. The measurements were fitted to the equation: Hz/(J.mol-‘)
= x(1-x)
t A,(1 -2x)‘-‘,
(1)
i=l
TABLE
2. Coefficients Ar of the fitting equation (1) for
.W,,H,,W+ (1-xLH,, (I--07% (1 - x)C,HCl, ( 1 - x)C,Cl,
868.436 1451.704 -521.436 245.408
284.125 858.421 -447.215 81.751
Hk at 298.15 K and standard deviations s
6.499 792.092 - 340.095 0.028
166.957 - 242.376 - 148.702 -40.333
427.478 - 1403.783 152.529 7.775
2 5 4 1
HE (cis-9-OCTADECENOIC ACID + ORGANIC LIQUID)
821
x FIGURE 1. Excess molar enthalpies Hk for {x(cis-9-C,H,,CH:CHC,H,,CO,H) + (1 -x) (C,H,, or C,H, or CCI,:CHCl or CCl,:CCI,)} at 298.15K: x, C 6H 14;0, C,H,; n , C&C: Ccl,; A, CI,C : CHCI; -, calculated from equation (1) with the coefficients from table 2.
by use of the unweighted least-squares method. The coefficients Ai and the standard deviations s are summarized in table 2. Curves calculated from equation (1) are also shown in figure 1; {s . (J . mol- ‘)/Hi(max.)} < 0.2 for mixtures containing chlorinated compounds and co.01 for the others, where HE(max.) denotes the maximum value of HE with respect to mole fraction. As shown in figure 1, HEs are positive over the whole composition range, with the exception of (oleic acid + trichloroethene) where an inversion of the sign of Hz was observed. These negative values indicate that interactions between oleic acid and trichloroethene overweight the contributions due to the breaking of interactions between like molecules. REFERENCES 1. Yanes, C.; Pellicer, J.; Rojas, E.; Zamora, M. J. Chem. Thermo&namics 1979, 1I. 177. 2. Lundberg, G. W. J. Chem. Eng. Data 1964, 9. 193. 3. Savini, C. G.; Winterhalter, D. R.; Kovach, L. H.; Van Ness, H. C. J. Chem. Eng. Data 1966, 11, 40. 4. Touhara. H.; Ikeda, M.: Nakanishi, K.; Watanabe, N. J. Chem. Thermodynamics 1975, 7, 887.