J. Chem. Eng. Date 1902, 27, 333-335
- x ) ] = EA,(&
VE/[x(l
+
- 1)’
where x is the mole fraction of 0-xylene for all of the systems. The solld lines of Figure 1 are those calculated from the smoothing equation. The coefficients of eq 1, their respective standard deviatkns, and the standard devlatlons for the excess volumes are given in Table 11. The results for these systems can be compared wlth those obtained for benzene n-aikanes (5) and p-xylene n-ad kanes (4). Both o-xylene and p-xylene n-alkanes systems show a very similar behavior. Excess volumes are slightly smaller for those systems were p-xylene is one of the compounds. The most remarkable difference is that the excess volume for o-xylene noctane changes sign (from positive to negative) as the mole fraction of o-xylene increases, while p-xylene noctane always shows a positive excess volume.
+
333
+
+
+
+
The excess volumes for benzene n-alkanes are always poslthre and are largerthan thosefound forxyisne n-akanes. These systems show a more ideel behavior which is probably due to the methyl groups in the aromatic ring.
+
Literature Clted (1) Tlm”uvrs, J. “Phyab4bfnlcal Constants of Wary System”: Interscbnoe: New York, 1959; Vd. 1. (2) Bettlno R. U”.Rev. 1971, 77, 5. (3) Handa, Y . P.: Betwon G. C. FkrJdphese €q&. 1979, 3, 185. (4) ~ c e r s eA h s o , M.;Nukz Delgado, J. J . U”.77wmdyn. 1981. 13, 1133. (5) Dlez Peiie, M.: Nuiiez Debado, J. An. oukn. 1974, 70, 878. (6) Dler P +I M.;Nuikz Delgf~do,J. An. ouhr. 1977, 73, 24. (7) Mar Pena, M.;Nukz Delgado, J. J . Chem. Thennodyn. 1975, 7, 201. (8) Drebbach, R. R. “Advances In C%emWy Series”: Amerlcen chemicel Soclety: WasMngton, DC, 1955: No. 15, p 14. Recehred for review October 28, 1981. Accepted March 29, 1982.
Excess Enthalpies of Binary Systems of Cyclic Ether Cyclohexene
+
Jean-Plerre E. Groller,*t Amerlco Inglese,t and Emmerlch Wllhelm*§ Centre de Thwmo@“ique et de Microcalorlm6trie du C.N.R.S..F- 13003 Mmeille, France
The molar excess enthalpy HEhas h n measured as a function of mob fraction x at atmsphwk pressure and 298.15 K for the M a r y Mquld systems cyckhexene (c-C,Hlo) oxdane (tetrahydrofuran, C4H80), oxane (tetrahydropyran, CIHloO), 1,3dbxolane (1,3-CaH,O,), 1,ddkxae (l,cC4H,02), and cyclohexane (c-C,H,,), by wing a flow calorimeter of the Picker dedgn. The mlxtwes wtlh cyclic dlethers exhibit relatively large podHve e x c w enthalpies: for 1,8-C,H,O2 4c-C,Hlo, He(, = 0.5) = 1155.5 J mol-‘; and for 1,4-C4H80g c-C8Hlo, HE(x= 0.5) = 909.7 J mol-’. The excess enthalpy for C4H80 c-C,Hlo b conrlderably smaller, Le., He(, = 0.5) = 285.5 J mol-‘, and CIHloO c-C,Hlo rhows $-shaped dependence of HEon x , wlth the very small negatlve section belng h a t e d at small mole fractlonrr of the c y c k ether ( x < 0.0899). For c-C,H,, c-C,Hlo the excess enthalpy b rather symmetric, wlth HE(x = 0.5) = 97.3 J
+
+
+
+
+
exptl
cyclohexene
806.0
cyclohexane oxane oxolane 1,4dioxane 1,3dioxolane
773.9 879.1 881.9 1028.2 1059.1
15.
m.9 lit.
806.09 (91,806.3,‘‘ 805.66 (111, 805.9 (12), 805.70 (13) 713.89 (14) 879.22b 881.97 (16) 1028.21 (1 7), 1027.97 (18) 1053.8‘
Interpolated value from ref IO. Interpolated vdue from ref Extrapolated value from ref 19.
+
+
&‘.
Introduction Excess enthalpies of binary liquid mixtures composed of either fiveor slx-membered cyclic ethers and various second components (ranging from n-aikanes to alkanoic aclds) were reported in ref 7 -5. As a sequel, we present here measurements of the molar excess enthalpy HE at 298.15 K of the oxolane (tetrahydrobinary systems cyciohexene (C-C&) oxane (tetrahydropyran, C,HloO), 1,3difuran, C,H,O), 1,ddloxane (1,4-C,H,02), and cyoxolane (1,3-C3H,,02), clohexane (c-C6Hlp). These measurements will be used later to assess, in terms of group-contribution theory (6),the infiu-
+
+
P/&g
compd
+
+
+
Table I. Densities (p) of Pure Component Liquids at 298.15 K
+
+
R e n t address: Laboratoke de Thennodynamlque et CinQiqua Chimique. UnhrersU de Ckmont 11, F-63170 Aubl&e. France. *Resent address: Isthto dl Chlmlca Fklce, UnlversltH di Bed, Barl, Italy. ‘On leave from Instltut fW Physlkalische Chemle, Unlversitlrt Wlen, WMngerstrasse 42, A-I090 Wlen, Austria. 0021-9568/82/ 1727-0333$01.25/0
Table 11. Comparison of Experimental Molar Excess Enthalpies HE at 298.15 K of the Test System Benzene &) + Cyclohexane (1 - x ) with the Results of Marsh (20) HE/(J mol-’) X
exptl
Marsh (20)
0.2118 -0.9 519.3 523.8 0.3064 -0.4 667.2 669.7 0.4015 756.2 761.8 -0.7 0.4920 793.7 798.5 -0.6 779.9 787.2 0.5768 -0.9 0.6581 -0.6 729.3 733.8 0.7400 638.3 636.2 +0.3 0.9334 214.6 214.7 0.0 Percentage deviation 6 = 100(HE,,,~~- HE~vIarsh)/H EM=&.
ence of various structural parameters (ring size, proximity of oxygen in diethers, n-?r interaction, etc.) on the thermodynamic behavior of such mixtures.
Experlmenlal Section MaferlSEs. Source and treatment of the cycloethers have been given previously ( 1 ) . Cyciohexene (from Fluke, puriss., 0 1982 American Chemical Society
984
JOWIWIof
chemical and ~ n g k w r h g &eta,
VOI. 27, NO. 3, 1982
Table 111. MdPr Excess Enthalpy HE for Cyclic Ether + Cyclohexene and for Cyclohexane + Cyclohexene at 298.15 Ka
+ (1- x ) cC,H,, 14.4 0.5431 97.3 45.0 0.6297 91.7 58.0 0.7265 80.0 75.9 0.8238 60.0 88.7 0.9178 31.5 95.2 x C5H,,0 + (1 - x ) &,HI, 0.0495 0.5825 148.1 -11.5 0.0794 -1.5 0.6697 136.6 0.2270 69.8 0.7540 114.3 0.3195 109.4 0.8704 66.9 0.4965 0.9597 18.4 148.5 x C,H,O + (1 - x ) cC,H,, 0.0591 14.6 0.6 126 279.2 0.1831 132.5 0.6935 251.2 0.2358 181.4 0.7794 207.0 0.3341 242.2 0.8615 144.6 0.4285 276.8 0.9369 69.4 0.5224 286.0 x 1,4C4H,02 + (1 - X) cC,H,, 362.7 0.0899 0.6 151 850.7 0.2518 755.1 0.6990 762.7 860.4 0.3498 0.7784 629.8 0.5304 900.3 0.8850 368.0 x 1,3C3H602+ (1 - x ) cC6HIo 0.1080 520.4 0.7400 898.3 0.2920 1008.3 0.8115 726.3 0.3973 1133.9 0.9042 414.3 0.5806 1112.7 0.9709 133.7 0.6620 1028.4 Mole fraction of cyclic ether or cyclohexane is x. x cC6H,,
0.045 1 0.1442 0.1883 0.2738 0.3604 0.45 12
purity > 99.5 mol %) was shaken with mercury and distlwed in its presence (7). Cyclohexane was from Fiuka (purlss.), with stated purity > 99.5 mol%. I t was used without further puriRcatkn. Before aohral measuement, all lquids were dried with molecular sieve (Union Carbkle Type 4A, beads, from Fluka). Densities of the pure liquids were determined with a vlbrathgtube densimeter ( 8 )and are compared with rekble ilterature values (9-79) in Table I. Cduhefty. Miar excess enthalpies were deteras previously ( 7 -5) with a flow calorimeter of the Picker design equlpped with separators and operated in the dlscontlnuous mode. The liquids were partially degassed before being transferred to the separators. The performance of the calorimeter was checked by measuring HE of some well-investigated test mixtures, such as tetrachioromethane benzene, and benzene cyclohexane. Agreement with literature data (20) was generally wlthln 1 %, as evklenced by representative resub obtained for the latter system (Table 11).
+
+
Resutts and Dkcurrkn Results of our measurements of HEfor the five binary systems at 298.15 K are listed in Table 111 and are graphically
1000
c I
//
0
04
02
06
08
Figuoi. ~ e x c a s " t p b s H E o f b h a r y " s 0 f c y d i C e t h e r cycbhe~xene,and c y c k h m cycbhexene,at 208.15 K, @otted agalnstmolefractlonxofoycwc~orcy~xane. Pdntsdenole expcwknentei results: (.) cyc&hemne cyckhexene; (A)oxane cyckhexene; (A)oxdane 4- cyclohexane; (0)1,cdkxmo cy* hexens; (0)1,3-doxOlarn, cycbhem. are W-es representations of results by eq 1 with parameters from Table IV.
+
+
+
+
+
cvves
+
+ x C,H,O
+ x 1,4-C,H80, + x 1,3C,H,O,
389.3 592.3 1142.0 3638.9 4622.0
15.1 106.6 54.4 -284.6 -334.3
+
presented in Figure 1. These resolts were fitted by unwelghted least-squares polynomial regression according to n-1
HE/(J mor') = x(l
- x ) /=o
A&
- 1)'
(1)
where x denotes the mole fraction of either cyclic ether or cyclohexane. Values of the coefflcients A, and standard deviations u(H7 are sumnarbed in Table IV. wlth the exoeplkn cycbhexene, Iu(H~)IH~,I < 0.01, of the system oxane where HE, is the extreme value of the molar excess enlhelpy with respect to mole fraction. The curves In Figure 1 were calculated from eq 1 with these coefflcients. Literature data for cornpartson could only be found for cyclohexane cycbbxene (72,27,22).The resub of Qiknzel and B M c h (27),Le., Hyx = 0.5) = 54.5 J mol-', are much lower than ours, whereas the excess enthalpies presentedby Letcher and Sack (22)have to be regarded as being too high: at x = 0.5 their value for HEdeviates by 18 J mor1from our HE = 97.3 J mor'. Though we are unable to explain these differences, we note that densities reported earlier by Letcher and Marsicam (23)are in variance with Meratwe data (9- 73) and with the density determined by us: at 298.15 K these authors give p = 815.5 kg ma, which is larger by about 9 kg m4 than any value given in Table I.On the other hand, the "entsof Wdycrckl(72) are in reasonable accord with ours, though slightly smaller: at 298.15 K he reports HEI(J mor') = x(1 - x)[368.0 - 4.9(2~- I) 5.1(2x - I)*]. The series of systems formed by mixing oxane, oxdene, l,ddkxane,and-,1 with cycbhem exh#ts vakres of HE which become progresshrely more posithre (oxane cycbhexeneshows sshepeddt3p"ceon x, with the very small negative sectlon located at x < 0.0899).This behavior
+
+
+
+
Table IV. Coefficients A iand Standard Deviations &IE) for Representsition of Excess Enthalpies HE at 298.15 K by Eq 1
(l - x ) c C 6 H , 0 x cC,H,, + x C5H,,0
1
U
5.7 -149.0 77.8 650.7 781.9
35.7 341.9 539.8 -312.3
-476.8 -788.0
0.7 1.8 2.7 5.2 6.0
J. Chem. Eng. Date 1902, 27, 335-342
parallels the increase of the relative oxygen content of the ether molecules. We note that, in general, the excess enthalpy of cyclic ether cyclohexene is distinctly smaller than that of the corresponding system cyclic ether cyclohexane ( 2 , 2 4 , 2 5 ) : at x = 0.5, these Increments vary between ca. -400 and -700 J mol-’.
+
+
Uterature Cited (1) . . Inpkse, A.; Wi)helm, E.; Grdier, J.P. E.; Kehiaian, H. V. J . Chem. 1980. 12, 217. (2) I-, A.; Wihelm, E.; GroUer, J.P. E.; Kehiaian, H. V. J . Chem. 1980, 12, 1047. (3) Ingiese, A.; Whelm, E.; Grdler, J.-P. E.; Kehiaian, H. V. J . Chem.
[email protected], 13, 229. (4) Wrlldm. E.; Inglese, A.; Grdler, J.P. E.; Kehiaian, H. V. J . Chem.
[email protected], 14, 33. (5) Wllhelm, E.; Ingle-, A.; Grolier, J.-P. E.; Kehiaian, H. V. J . Chem. lkm@wl., in p-. (6) Kehialan, H. V.; GroUer. J.-P. E.; Benson, G. C. J . Chlm. M y s . pnYs.-Ch/m. Bkl. 1978, 75, 1031. (7) Andrews, A.; Morcom, K. W.; Duncan. W. A.; Swlnton. F. L.; Pollock, J. M. J . Chem. 7?“@m.1970, 2 , 95. (8) Whelm, E.; Groller, J.P. E.; Karbaial Ghasseml, M. H. Monatsh. Chem. 1978. 109, 369. (9) Fonlatl, A. F.; Camin, D. I.;Rosslnl, F. D. J . Res. Mtl. Bur. Stand. (US.)1950, 45, 406.
-.
w.
335
(10) Tlmmermans, J. “Physlcc-Chemlcal Constants of Pure Organic Compounds”; Elsevier: New York, 1950; Vol. 1. (11) Harrls, K. R.; Dunlop, P. J. J . Chem. Thennodyn. 1970, 2 , 813. (12) W6ycicky, W. J . Chsm.
[email protected], 12, 165. (13) Letcher, t. M. J . Chem. Thennodyn. 1977, 9 , 661. (14) Rkldlck, J. A.; Bunger, W. B. “Techniques of Chemlstry”, 3rd ed.; Weissberger. A., Ed.; Wiley-Interscience: New York, 1970; Vol. 2. (15) Landolt-BiKnstein. Zahlenwerte und Funktlonen, 2 Band, 1 Tell. 6 Aufiage; Springer: West Berlin. 1971. (16) Klyohara, 0.;DArcy, P. J.; Benson, G. C. Can. J . Chem. 1979, 57, 1006. (17) Anand, S. C.; Groller, J.-P. E.; Klyohara, 0.; Benson, G. C. Can. J . Chem. 1973, 51, 4140. (16) Hammond, B. R.; Stokes, R. H. Trans. FaradaysoC. 1955, 51, 1641. (19) Bellsteln, “Handbuch der Organischen Chemie”, 19 Band, 1 Erg&nzungswerk, 4 Auflage; Springer: Berlin, 1934, p 609. (20) Stokes, R. H.; Marsh, K. N.; Tomllns, R. P. J . Chem. 7Mrmcdyn. 1969, 1 , 211. Marsh, K. N. Int. Data Ser.. Se/. Data MomVes, Ser. A 1973, 2, 3. (21) O%nzel. K.; Blttrlch. H. J. 2.phvs. Chem. (Le/&) 1977, 258, 1073. (22) Letcher, T. M.; Sack, J. J . S.Afr. Chem. Inst. 1975, 28, 316. 1974, 6 , 509. (23) Letcher, T. M.; Marslcano. F. J . Chem. 7Wr-n. (24) Andrews. A. W.; Morcom. K. W. J . Chem. 7bermodyn. 1971. 3 , 519. (25) Cabani, S.; Ceccantl, N. J . Chem. Thennodyn. 1973. 5 , 9.
Received for review November 3, 1961. Accepted April 13. 1982. Financial support wlthln the frame of the Austrian-French treaty for scientific and technical cooperation 1s gratefully acknowledged by E.W.
Heat Capacities of Aqueous Solutions of NiCI2 and NiC12.2NaCI from 0.12 to 3.0 mol kg-’ and 321 to 572 K at a Pressure of 17.7 MPa David Smlth4agowan,t Robert H. Wood,’ and David M. Tiliett Department of Chemistty, University of Delaware, Newark, Delaware 1971 1
The heat capacity of aqueous NICI, and aqueous NICi2*2NaCIhas been measured at temperatures from 321 to 572 K at a pressure of 17.7 MPa by using a new flow calorhneter. The results for NICI, do not show the large negative apparent molar heat capacities characteristic of strong electrolytes at high temperatures and low moiafflles. This indkatw that NICI, at 572 K is mainly un-lonlred. The apparent molar heat capacity of NICI2.2NaCI could be predicted with reasonable accuracy, by wlng Young’s rub and the apparent molar heat capaclti.r of pure NICI, and NaCi. This WCCOGI indicates that Young’s rule can be used to calculate the heat capacity of NICI, in any mixture with NaCi. Equallons are M v e d whkh allow the present remits together with room-temperature data to be used to calculate enthalpies and free energies of aqueous NICI, at hlgh temperatures. The Integrals of the apparent molar and partial molar heat capacities needed in these equations are tabulated. Introduction This investigation of the heat capacities of NCIPsolutions at high temperatures, complementing our previous study of NaCl heat capacities ( I ) , was undertaken for two reasons. First, we wanted to contrast the relathrely simple behavior of NaCl solutions at hlgh temperatures with a system more likely to exhibit complex thermodynamic behavior. Ludeman and Franck ( 2 ) , In their spectroscopic investigation of aqueous NiCI, solutions, for example, found dramatic changes In the absorption spectrum near 200 OC. Second, we wanted to demonstrate that our Current address: Westinghouse Research and Development Center, Pltts-
burgh. PA 15235.
0021-9568/82/ 1727-0335$01.25/0
Table I. Densities of the Solutions at 1 atm and 25 “CY
ml
dl(g
(mol kg-I)
NiCl,
cm-7 NC1,. 2NaCl
0.1202 0.985 45 0.5286 0.937 78
ml
dl(g
(mol kg-I)
NU,
0.976 11 0.9940 0.885 42 0.94944 2.995 0.681 25 The density of water used was 0.997 04 g cm-$.
cm-9 NiCl,. 2NaC1 0.899 32 0.821 32
calorimeter could be used to investigate industrial problems assoclated with hightemperature aqueous systems. Extensive use of nickei-containing alloys in nuclear power plants has resulted in several corrosion problems, yet very little is known about aqueous nickel species at high temperatures. These problems include stress-corrosion cracking which may result from NiCI, concentrations in crevices and sludge piles (3). Postiewait’s investigationimplicates chloride in the corrosion of nickel at temperatures up to 274 OC (4). Migration of radioactivity throughout steam-generating circuits is a serious problem which is dependent on nickel speciation at high temperatures (5-7). The measurements reported here allow the calculation of the apparent molar and partial molar heat capacities, the change in the enthalpy and the partial molar enthalpy, and the change in the chemical potential as functions of molality and temperature for aqueous NICI, and NICI2.2NaCI. The results allow the calculation of equilibria involving aqueous NiCI, alone or in the presence of NaCl at molalities from 0.12 to 3.0 mol kg-‘ and temperatures from 298 to 575 K.
Experlmental Section So/ut/ons. A stock solution of approximately 3.0 mol kg-’ NICI, was prepared from Fisher certified NiCI,.2H,O, the actual
0 1982 American Chemical Society
