EXCESS VOLUMES AND VISCOSITIES OF DIOXANE- PYRIDINE MIXTURE BY M. V. PRABHAKARA RAO AND P. R. NAIDU (Sri Venkateswara University Chemical Laboratories, Tirupati) Received May 17, 1973 (Communicated by Prof. M. Santappa, F.A.sc.) ABSTRACT Excess volumes and viscosities of binary liquid mixture, Dioxane- Pyridine, were determined at 30 C and 40 C. The excess volumes were analysed in the light of Flory theory. The viscosity results were employed to test the validity of viscosity relations formulated by Grunberg and Nissan and Katti and Chaudhri. INTRODUCTION THE statistical theory developed by Flory 1,2 for binary liquid mixtures has been extended to mixtures containing one polar component by Nigam and Singh3 and Raman and Naidu. 4 These workers treated the single parameter defined by Flory as an adjustable quantity in the analysis of excess volume data. In the present study an attempt has been made to extend the theory in its original form to the system Dioxane-Pyridine. Pyridine in the system is a polar component and hence the system provides a test to the applicability of the theory to the mixtures containing one polar component. In the present investigation an attempt has also been made to study the applicability of viscosity relations proposed by Grunberg and Nissan and Katti and Chaudhri 6 to the mixture. EXPERIMENTAL Measurement of excess volume.--the experimental values of excess volume have been obtained at 30 C and 40.0 + 0.010 C from precision density values of liquids and liquid mixtures, determined by the Pyknometric method described earlier. 7 The values are accurate to ± 0.02 ml/ mole. 65 Acad. A3
66 M. V. PRABHAKARA RAO AND P. R. NAIDU Measurement of viscosity. Viscosities of pure liquids and liquid mixtures at 30 C and 40 C have been determined using an Ostwald Viscometer and the q values are accurate to + 0.5%. Purification of liquids. Dioxane and Pyridine were purified by the methods reported by Chowdary et al.s The purity of the components have been ascertained from density and boiling point data (Dioxane: b.p. 101.4 0 C (lit. 9 101.43 C) ; Density: 1.0222 (lit. 9 1.0223), Pyridine: b.p. 115.4 C (lit. 9 1155 C); Density: 0.97295 (lit. 9 0.97281). TEEORETICAL Excess volume. The equation for excess volume VE developed by Flory takes the form: VE = vecal. (X1V1 * + X2V2 *) (1) where vecai. is the calculated excess reduced volume which is related to the ideal reduced volume " 0, ideal reduced temperature T and the reduced temperature T of the mixture by the equation vecal. _ (v"o)7/3 [4/3 (5 0) l/3)-1 (T To ) (2) The reduced temperature of the mixture is given by the relation = r g1p1 *T1 +02P2*T2 i L1 _ 0102X12 1-1 (3) L 01P1 * + 02P2 * 01P1* ± 02P2 * J where X1, Vi*, P**, vo, T, T, 0 2 and X12 have the same meaning as described by Flory. 02 and X 12 are related to the properties of the pure components as follows: _ 02 02 / e2 02 + 01 (^+2^ 02 + 01 f Vi J l/3 (4) `j2* 1/6 p 2* 1/ 2 1 2 X12 PI* L 1 \VI*/ PL*J J (5) where S 1 and S2 denote the ratio of the molecular surface areas of contact per segment.
Excess Volumes & Viscosities of Dioxanepyridine Mixture 67 Viscosity relations. Grunberg and Nissan,' using the empirical relation of Arrehenius, suggested that in the case of non-ideal mixtures ln'9 = Xlln'qi + X21ng 2 + X,X 2d (6) where 'd' is a constant treated as an approximate measure of the strength of the interaction between the components. Katti and Chaudhri, 6 using Reed and Taylor's equation for idea solution, formulated In'9 8 Vs = X, 1nq,V1 + X21n'q2V2 + X1X2 RT (7) represents the inter- for non-ideal binary liquid mixtures, where W action energy between components. RESULTS AND CALCULATIONS Values of VE at 30 C and 40 C are presented in Table I. The values of YE are zero at two compositions and the non-zero values a t other compositions are within the limits of experimental error. TABLE I Mole fraction Density gm.m1 ' Excess volume VE cm 3 mole-' of -- Dioxane 30 C 40 C 30 C 40 C 0 0000 0 9729 0 9629.... 0 1026 0.9783 0 9681 0 00 0 00 0 2999 0.9884 0 9780 0.01 0.01 0.4956 0.9981 0.9877 0 00 0 00 0.7016 1 0080 0.9972 0.01 0 8997 1.0176 1.0065 0.01 0.03 1.0000 1 0222 1.0115..
68 M. V. PRABHAKARA RAO AND P. R. NAIDU The values of the parameters B 2 and X12 are derived from equations (4) and (5). These are in turn employed to determine T, the reduced temperature of the mixture, using the relation (3). The parameters required for the calculation of T are computed from the data reported in literature 11,12 and the values of these parameters are presented in Table II. Finally the excess volume, VE, over the whole range of composition, are calculated with the aid of equation (1). The calculated values of VE and those of the parameters 0 2 and X12 are presented in Table III. TABLE II Parameters of the pure components at 30 C Component ax 10 3 y v V V* P* T deg.-' atm.deg.-1 cros. mole-' cm 3.mole-1 J.ml-1 Dioxane.. 1.132 1 490 1.277 86.19 67 45 737 2 0 06130 Pyridine.. 1.004 1.362 1 253 81 30 64 86 517 1 0 05672 TABLE III Mole fraction VB, of 92 X12 cm$.mole-1 Dioxane J.cm 3 at 30 C 0 1026 0 895 20 81 0.07 0 2999 0 695 20.81 0 37 0.4956 0 498 20 81 0.58 0 7016 0 294 20.81 0.33 0 8997 0.098 2081. 0 22 The values of 'd' and W,. appearing in equations (6) and (7) are calculated over the entire range of composition at 30 C and 40 C from
Excess Volumes & Viscosities of Dioxanepyridine Mixture 69 the observed viscosities of pure liquids and liquid mixtures. The results are given in Table IV. TABLE IV Mole fraction v Centipoise d W,,.,. Cal.mole-1 of --- --- Dioxane 30 C 40 C 30 C 40%C 30 C 40 C 0.0000 0.819 0.713.. 0.1026 0.842 0-728 0.00 0.04 3-0 23-9 0.2999 0 894 0.767 0.03 0.00 17.4 5.8 0.4956 0.940 0.800 0.00 0.02 9.1 9 1 0-7016 0.990 0.836 0.04 0.04 1-5 23.3 0.8997 1.045 0.881 0.08 0.04 3.8 24.8 1.0000 1-075 0.906.. DISCUSSION The almost zero values for Vz at 30 C and 40 C over the whole range of composition show that the system is approximately ideal in behaviour. Also the VE values point out that the excess volume is not influenced by change in temperature. The values of VF of the present study are in agreement with those reported at 30 C by Chowdary et al. 8 A comparison between the observed YE values (cf. Table I) and those calculated (cf. Table III) in terms of Flory theory at 30.0 C shows that there is no agreement between them, both in sign and magnitude. Hence it is concluded that the theory cannot be extended to Dioxane-Pyridine mixture. Chowdary et al. 8 analysing the excess volume data in terms of average potential model due to Prigoginels also found that the model in its original form does not apply to this system. The values of `d' and W. presented in Table IV are very small and they are of the order of experimental error. These values indicate that the system is ideal in behaviour not only with respect to excess volumes but also in terms of Viscosity data. The ideal behaviour of the system is
70 M. V. PRABHAKARA RAO AND P. R. NAIDU also born out by the linear dependence of viscosity on composition plotted in Fig. 1. 1.0 W 0 a. Z 0.9 W 4V, r^ 0.8 0.7 0 0.2 0.4 0.6 0.8 1. O MOLE FRACrION OF DIOXANE Fta. I ACKNOWLEDGEMENTS One of the authors (M. V. P. Rao) is thankful to the Council of Scientific and Industrial Research, New Delhi, for the award of Junior Fellowship. REFERENCES 1. Flory, P. J... J. Amer. Chem. Soc., 1965, 87, 1833. 2, Abe, A. and Flory, P. J.,. Ibid.. 1965, 87, 183$,
Excess Volumes & Viscosities of Dioxanepyridine Mixture 71 3. Nigam, R. K. and Sing, P. P. 4. Raman, G. K. and Naidu, P. R. 5. Grunberg, L. and Nissan, A. M. 6. Katti, P. K. and Chaudhri, M. M. 7. Rao, M. V. P. and Naidu, P. R. Ind. J. Chem., 1969, 7, 156. Proc. Ind. Acad. Sci., 1973, A 77, 263. Nature, 1949, 164, 799. J. Chem. Engng. Data, 1964, 9, 442. Ind. J. Tech. (In press). 8. Chowdary, M. C., Naidu, Ind. J. Chem., 1969, 7, 796. P. R. and Krishanan, V. R. 9. Timmermans, J... Physico Chemical Constants of Pure Organic Compounds, Elsevier, Amsterdam, 1950. 10. Read, T. M. and J. Phys. Chem., 1959, 63, 58. Taylor, T. E. 11. Hydherkhan, V... Ph.D. Thesis, Sri Venkateswara University, 1972. 12. Nomoto, O... J. Phys. Soc. Japan, 1963, 18, 1526. 13. Prigogine, I... Molecular Theory of Solutions, North Holland, Amsterdam 1957, pp. 196.