J. Chem. Eng. Data 1985, 30, 491-492
ments is adequate in regions common to both data sets. The new data present a more thorough analysisof the near-critical region; within 10% of the critical pressure, the data follow asymptotic forms of the scaling relations (eq 2 and 3).
Acknowledgment Special thanks goes to Dr. Del D. Fussell who orginally interested us in the study of interfacial tensions. parameters in eq 5 and 6 pressure critical pressure liquid-phase mole fraction vapor-phase mole fraction scaling-law parameters (critical indices) interfacial tension uncertainty in measured interfacial tension liquid-phase density vapor-phase density liquid-phase density minus vapor-phase density
49 1
Literature Clted (1) Wagner, 0. R.; Leach, R. 0. SOC.Pet. Eng. J. 1088, 6, 335. (2) Bardon, C.; Longeron, D. G. SOC.Pet. Eng. J . 1080, 20, 391. (3) Brauer, E. B. Ph.D. Dissertation, The University of Texas, Austin, TX, 1961. (4) Simon, R.; Roman, A,; Zana, E. SOC. Pet. Eng. J. 1978, 78, 20. (5) Jennlngs, H. Y. Rev. Sci. Instrum. 1088, 39, 386. (6) Fordham, S. Proc. R. SOC.London., Ser. A 1048, 794, 1. (7) Sage, B. ti.; Lacey, W. N. "Thermodynamic Properties of the Lighter Paraffin Hydrocarbons and Nitrogen"; Monograph on API Research Project 37; American Petroleum Institute: New York, 1950. (8) Stegemeier, G. L. Ph.D. Dissertation, University of Texas, Austin, TX, 1959. (9) Olds, R. H.; Reamer, H. H.: Sage, B. H.: Lacey, W. N. Ind. Eng. Chem. 1040, 4 I 475. (10) Brauer, E. 6.; Hough, E. W. Prod. Mon. 1065, 29, 13. (1 1) Levelt Sengers, J. M. H.; Greer, W. L.: Sengers, J. V. J . Phys. Chem. Ref. Data 1078, 5, 1. (12) Le Guiilou, J. C.; ZinnJustin, J. Phys. Rev. B 1980, 27, 3976. ~
Received for review July 30, 1984. Accepted May 24, 1985. Financial support for this work was furnished by the following organizations: Amoco Production Research Co., ARC0 011 and Gas Co., Chevron Oil Field Research Co., Cities Service Co., Exxon Production Research Co., Marathon Oil Co.. Mobil Research and Development Corp., Shell Development Co., Sun Exploration and Production Co., and Texaco, Inc.
Enthalpies of Mixing of Tetrahydrofuran 4- y-Butyrolactone and y-Butyrolactone Systems at 299.15 K Water
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D. H. S. Ramkumar and A. P. Kudchadker" Depatfment of Chemical Engineering, Indian Institute of Technology, Bombay, India
D. D. Deshpandet Department of Chemistry, Indian Institute of Technology, Bombay-400 076, India
Enthalpies of mixlng have been reported for the systems y-butyrolactone and water tetrahydrofuran (THF) y-butyrolactone at 299.15 K and 1.013 bar. Data have been fitted to the Redllch-Klster type equallon.
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Introduction Enthalpies of mixing AHm are necessary for the treatment of isobaric vapor-liquid equilibrium data as well as in distillation column design calculations. I n our present thermodynamic y-butyrolactone studies of tetrahydrofuran (THF) water system, AH'" data are available only for the tetrahydrofuran (THF) water system (1-3). Hence, it was decided to measure AH'" data for the binary mixtures (i)THF y-butyroy-butyrolactone. lactone and (ii) water
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Table I. Enthalpies of Mixing, AHm,of the THF S y s t e m at 299.15 K
AH"'/J present values"
0.0476 0.1572 0.2572 0.5123
-504 -743 -625 -215
Of14 J mol-'. * f 4 t o f 8 0.049. 'At XTHF = 0.05.
J
Materials. Tetrahydrofuran (THF), supplied by Sarabhai Chemicals, India, was found to be 99.68 mol % pure by GC on a column packed with Carbowax 20M using thermal conductivity detector. Double distilled deionized water with 2 pmho cm-' electrical conductivity was used for the measurements. Present address: Polymer Lab, Department of Chemistry, McGill university, Montreal, Canada.
0021-9568/85/1730-0491$01.50/0
a t 298.15
I* -534d -730 -650 -200
K r e f 2c
ref
mol-'.
-527e -740 -657 -213
Cf8 J mol-'.
dAt XTHF =
Table 11. Enthalpies of Mixing AHmof the T w o Binaries at 299.15 K X
W / J mol-' x(Water) + (1-
x ) (y-Butyrolactone)
Experlmental Section
mol-'
at 299.15 K, XTUR
+ Water
0.1237 0.1971 0.3909 0.4934 0.7163 0.8524 0.8932 0.9645 0.9703
237 619 915 774 96 14 5 -23 -26
A P /J mol-'
X
x(THF) + (1 x ) (y-Butyrolactone)
0.0957 0.1977 0.2944 0.3926 0.4891 0.5953 0.6953 0.9084
48 91 138 203 197 113 98 46
Fluka AG Switzerland make y-butyrolactone of 99.02 mol '70 purity, as determined chromatographicallyon a column packed with 12% EGS (ethylene glycol succinate) on Anakrom using thermal conductivity detector, was used. 0 1985 American Chemical Society
492 Journal of Chemical and EngineeringData, Vol. 30,
No. 4, 1985
T a b l e 111. Values of t h e A d j u s t a b l e Parameters of Eq 1 a n d S t a n d a r d D e v i a t i o n o(AHm)
svstem
x(THF) + (1 - X)’
C”
c,
740.9
-542.8
Cd
827.9
1823.1
14
790.3 7960.7 -6674.8
33
-1495.0
(y-butyrolactone) x(water) 2741.5 -5962.7 (1 - x ) . (y-butyrolactone)
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.(Awl
C,
C?
J mol-’
Caknknefry. Enthalpies of mixing were measured at 299.15 K and 1.013 bar with a Tian Calvet conduction calorimeter constructed by Deshpande and Prabhu ( 4 ) , and has been described in detail elsewhere (5,6).
Results
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Enthalpies of mixing were measured for the system THF water in our calorimeter at 299.15 K in order to check the performance of the calorimeter. The data are repotted in Table I together with the lierature values. I f the temperature effect is neglected, the agreement between our values and those of ref 7 and 2 is satisfactory. The uncertainty in our values is estimated to be f14 J mol-’. The experimental enthalpies of mixing for the two binaries, water y-butyrolactone and THF y-butyrolactone, at 299.15 K are given in Table I1 and are graphically represented in FQwe 1. The dependence of AHm on composition was represented by the Redlich-Kister type equation of the form:
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AH”(J mol-‘) = x(1 - x)[Co C,(2x - 1) C2(2x I ) ~ c,(~x - I ) ~ C4(2x- 1),]
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(I)
The adjustable parameters Co-C, were computed by the least-squares regression analysis and are given in Table I11 along with the standard deviation a(AHm). The values of 6(AHm)were obtained by using eq 2.
n- 1
-100 I
0
01
,
02
I
I
I
1
03
O L
05
06
__
I
I
I
07
08
09
-
’
0
X ~ ~ ~ / X ~ o t p r
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Flgure 1. Enthalpies of mixing of the water y-butyrolactone and y-butyrolactone systems at 299.15 K.
THF
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THF water and water y-butyrolactone systems which are polar in nature, the Redlich-Kister type of equation does not represent the data well. However, it is reported here for interpolation purposes for engineering applications. For the water y-butyrolactone system, the negative enthalpy of mixing at lower concentrations of y-butyrolactone may be due to the enhancement of water-water hydrogen bonding (“iceberg” effect), which is due to the structural influence of y-butyrolactone on water. This type of behavior In AHm is in agreement with the characteristic behavior of VE, and excess adiabatic compressibiliies for this system, measured by Werbhn and Lesinski (7). Similar observation for aqueous alcohol systems has also been reported by Franks (8).
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Regldry No. THF, 109-99-9; y-butyrolactone, 96-48-0.
where n is the number of experimental data points. Discusslon
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The enthalpy of mixing for water y-butyrolactone is comparatively higher than for the THF y-butyrolactone and THF water systems at equimolar concentrations. For the THF y-butyroiactone system, the fitting of the experimental data to the Redlich-Kister type equation was satisfactory. For the water y-butyrolactone system, the standard deviation is 31 J mol-’, which is twice the experimental uncertainty. We have also fitted the data of Nakayama et al. ( 7 ) for THF -t water system to eq 1. Their data also showed a standard deviation of 32 J mol-‘ which indicates that for the
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Llterature Cited Nakayama, H.; Shinoda, K. J . Chem. Thermodyn. 1971, 3 , 401. Signer, R . ; Arm, H.; Daeniker, H. Helv. Chim. Acta 1969, 52, 2347. Erva, J. Suom. Kemlstll. 6 1955, 28, 131. Deshpande, D. D.; Prabhu, C. S. Macromolecules 1977, IO, 433. Choudary, N. V.; Naidu, P. R.; Deshpande, D. D. Thermochh. Acta 1984, 74, 381. (6) Calvet, F.; k a t . H. “Recent Advances in Microcalorimetry”; Pergamon Press: New York, 1963. (7) Werblan. L.; Lesinski, J. Pol. J . Chem. 1980, 54, 507. (8) Franks, F. “Water - A Comprehensive Treatise”; Plenum Press: New York, 1973; Voi. 11. (1) (2) (3) (4) (5)
Received for review August 2. 1984. Accepted April 29, 1985. We thank Hindustan Lever Research Foundation, Bombay, India, for supporting this project.
