Lakhanpal, M. L.

Lal, Gurcharan

Mandal, H. G.

English

NOPR

Indian Journal of ChemistryVol. 14A, April 1976, pp. 231-233Thermodynamic Properties of Partially Miscible Systems:Part II- Binary Systems of Cyclohexane withAcetic Anhydride & FurfuralM. L. LAKHANPAL, H_ G_ MANDAL & GURCHARAN LALDepartment of Chemistry, Panjab University, Chandigarh 160014Received 27 August 1975; accepted 12 December 1975The activities of components and various thermodynamic properties of mixing of binarysystems of cyclohexane with acetic anhydride and furfural at 25° have been determined over theentire composition region. The data supports the earlier observations that the values of partialmolar enthalpy and partial molar entropy show sharp discontinuities at compositions corres-ponding to maximum mutual solubilities of the components. The values of excess entropyof mixing show that the systems exhibit restriction on random mixing only where concentra-tions of acetic anhydride and furfural are rather high.As an extension of our earlier+? work on thethermodynamic properties of some partiallymiscible liquid pairs, similar results on binarysystems of cyclohexane with acetic anhydride andfurfural at 25° are reported in this paper. Sincethe components have limited mutual solubilities,the solution vapour pressures need to be determinedwith high accuracy. This was possible to achievewith the availability of a differential micromano-meter+" and a modified oil-mercury manometer".Materials and MethodsCyclohexane, acetic anhydride and furfural werepurified by methods reported earlier". The mutualsolubilities of various liquid pairs were determinedwith the help of Zeiss interferometer. The solutionvapour pressures were determined as reportedearlier".Results and DiscussionAs reported earlier", the vapour compositions(YI) at different values of liquid compositions (Xl)were determined by the modified incremental method"based on the relationelYI = Yl(I-Yl) . elPP ... (1)Yl-Xlassuming the vapour phase to behave ideally. Itwas thus possible to evaluate the activities of thetwo components in each system. The values ofYl' al and a2 are given in Table 1.Thermodynamic and excess thermodynamic pro-perties - The values of M/", at 25° were extra-polated? from the valuesl-" of b..H", at 26·9° and48.2°. The thermodynamic properties of mixingb..G", and Tb..Sm were determined. For a typicalcase of cyclohexane (I)-furfural (2), the thermo-dynamic properties of mixing have been plottedin Fig. 1. The values of the various thermodynamicproperties over the partially miscible region areTABLE 1 - SOLUTIONPRESSURE, VAPOURCOMPOSITIONANDACTIVITIES OF VARIOUS SYSTEMSAT 25°C-"'"1 P Yl al a2(em)CYCLOHEXANE(1)-ACETIC ANHYDRIDE (2)0-0000 0-507 0-0000 0-00000 1·00000·0020 1-020 0-4654 0-04860 1-07550-0040 1-460 0-6272 0-09375 1-07350-0060 1-860 0-7079 0-1348 1-07160·0080 2-220 0·7557 0-1717 1-06980-0100 2-580 0-7901 0-2087 1·06800·0200 4-100 0-8690 0-3647 1-05950·0400 6-360 0-9168 0-5969 1-04420-0800 8-720 0-9405 0-8396 1-02340-1200 9-680 0-9470 0-9385 1·01130-1420 9-966 0-9488 0-9680 1-00680·9550 9-966 0-9488 0-9680 1-00680·9600 9-959 0-9511 0·9697 0-95990·9700 9-939 0-9597 0·9765 0·79020-9800 9-908 0-9697 0-9836 0-59290·9900 9-859 0-9822 0-9914 0-34560·9950 9·823 0-9900 0·9955 0-19451·0000 9-768 1·0000 1-0000 0-0000CYCLOHEXANE(1)-FURFURAL (2)0-0000 0·542 0·0000 0-00000 1-00000·0020 0-825 0-3312 0·02797 1-01810·0040 1-125 0-5105 0-05880 1-01590·0060 1·425 0-6144 0·08963 1-01390-0080 1·725 0-6821 0-1205 1-01180·0100 1-988 0-7246 0-1474 1-00990-0200 3-288 0·8350 0-2810 1-00060-0400 5-375 0-9008 0-4957 0-98390-0600 7·100 0-9261 0-6731 0-96850-0800 8-400 0-9384 0-8069 0-95550-1000 9-425 0-9457 0-9125 0-94410-1150 10-050 0-9495 0-9769 0-93620-9780 10-050 0-9495 0-9769 0-93620-9800 10-017 0·9576 0-9820 0-78400-9900 9-912 0-9760 0-9904 0-43960-9950 9-842 0-9876 0-9951 0-22571·0000 9·768 1·0000 1-0000 0-0000231300INDIAN ]. CHEM., VOL. 14A, APRIL 1976~ 10<;;;u.••.•.......................................................................................,~ ......" .200.....". -,....: ~S'".....". ".......-, »,..........~~~.....O~-----c~-----r~----~~------~------~1'1. 0'2 0'4 0·6 o-e 1·0AC,m xICYCLOHEXANE CI)- FURFURAL(2)-1000'230002000CYCLOHE1CANE (I) - ACETIC ANHYDRIDE (2 )1000AHI4t.(:·:·. ,."./ .IIIIIIIIIIIIIIIII.... , :10'6o 0'4 0'6MOlE FRACTION OF ACETIC ANHYDRIDE (."2)232Fig. 1 - Plots of thermodyna-mic properties versus mole frac-tion of component-l for cyclo-hexane (1)-furfural (2) systemFig. 2 - Plots of partial molarthermodynamic properties versusmole fraction of component-2 forcyclohexane (1)-acetic anhydride(2) system>- --tAI{HANPAL et al.: THERMODYNAMtC PROPERTIES OF BINARY SYSTEMSTABLE 2 - VALUES OF THE DIFFERENT PARAMETERS IN EQUATION (3) FOR VARIOUS SYSTEMS AT 25°Cll.H::' sn: x" xb k k' k* ll.HI (mix) ll. fh (mix)m I I(cal/mole) (caljrnole] (caljmole) (caljmole) (caljmole) (caljmole)CYCLOHEXANE (I)-ACETIC ANHYDRIDE (2)272·9 128·8 0·1420 0·9550 -1·230 144·1 -298'1 120·8 298'1CYCLOHEXANE (I)-FURFURAL (2)269·7 76·04 0·1150 0'9780 -1·159 193·7 -295·6 71'1 295'6linear functions of mole fraction, given by therelation (2)I~.xm (mix) = '~[(L\X:'-L\X~)XI +X~.L\X~n-X~.L\X:'JXl-Xl... (2)where x! and x~ are the mole fractions of compo-nent-I at saturation solubilities of component-Iin component-2 (phase a) and of component-2 incomponent-I (phase b), respectively. L\X:' andL\X~ are the changes in the thermodynamic pro-perties X at the compositions x~ and x~' respectively.It may be observed that L\Hm and TL\Sm tend tocompensate each other.Of particular interest are the values of the excessentropy of mixing (TL\S!). Unlike the partiallymiscible systems" with formic acid as one of thecomponents, these systems show negative valuesof TL\S! in the phases rich in associated liquids(acetic anhydride and furfural) and positive valuesin the phases poorer in associated liquids. Thisis on account of the fact that formic acid is muchmore associated than acetic anhydride and furfural.It appears that acetic anhydride and furfural retainsome association in solutions where their concen-trations are large but readily allow random mixingof solutions where their concentrations are low.Partial molar properties of mixing - For a typicalcase, cyclohexane (Ij-acetic anhydride (2), thepartial molar thermodynamic properties have beenplotted in Fig. 2. The values of the partial molar~:.'1thalpy over the partially miscible region werecal~ulated as reported earlier". Eq. (2) for L\Hmmay ~e expressed astlHm (mil')' = kk'Xl-k"whereIk---- X"_xb1 Ik' = L\H:' - L\H~... (3)... (4)... (5)kW = (x~L\H':,,-x~L\H~)/(~-x~)Accordingly,sii, = kk' _kIfandL\H2 =-k" ... (8)The values of the various parameters k, k', k",L\H:' and L\H~ are reported in Table 2 for boththe systems. The results illustrated in Fig. 2support the earlier conclusions that (i) partial molarproperties remain constant over the partially miscibleregion of composition, (ii) except for the partialmolar free energy, the partial molar enthalpy andpartial molar entropy show sharp discontinuitiesat compositions x~ and x~, and (iii) the values ofboth the partial molar enthalpy and partial molarentropy of mixing over the partially miscible rangeof composition lie between their values at com-positions x~ and x~ corresponding to their maxi-mum mutual solubilities..•• (6)... (7)AcknowledgementGurcharan Lal is grateful to UGC, New Delhi,for the financial assistance.References1. LAKHANPAL, M. L., KAPOOR, K. K., GURCHARAN LAL &MANDAL, H. G., Indian]. Chem., 11 (1973), 47t.2. LAKHANPAL, M. L., MANDAL, H. G. & GURCHARAN LAL,Indian]. Chem., 13 (1975), 673.3. LAKHANPAL, M. L., MANDAL, H. G. & GURCHARAN LAL,Indian J. Chem., 13 (1975), 1309.4. PUDDINGTON, I. E., Can. J. Res., B27 (1949), 15t.5. SIRIANNI, A. F. & PUDDINGTON, I. E., Can. J. Chem.,33 (1955), 755.6. LAKHANPAL, M. L. & CONWAY, B. E., Can, J. Chem.,38 (1969), 199.7. LAKHANPAL, M. L., GURCHARAN LAL & MANDAL, H. G"Indian]. Chem., 11 (1973), 1186.8. LAKHANPAL, M. L. & GURCHARAN LAL, Indian]. cu-«,13 (1975), 47.9. RAMALHO, R. S. & RUEL, M., J. chem, engng Data, 14(1969), 20.233

Thermodynamic Properties of Partially Miscible Systems: Part II- Binary Systems of Cyclohexane with Acetic Anhydride & Furfural

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Thermodynamic Properties of Partially Miscible Systems: Part II- Binary Systems of Cyclohexane with Acetic Anhydride & Furfural

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