J Madhumitha et al., IJSID, 2012, 2 (1), International Journal of Science Innovations and Discoveries

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1 ISSN: IJSID International Journal of Science Innovations and Discoveries An International peer Review Journal for Science Research Article Available online through A STUDY OF INTERNAL PRESSURES OF TERNARY AND SUB-BINARY LIQUID MIXTURES BY USING MOLAR REFRACTION AT DIFFERENT TEMPERATURES J.Madhumitha a, N.Santhi b*, G.Alamelumangai a and M.Emayavaramban a a Department of chemistry, Manonmanium Sundaranar Universuty, Tirunelveli b Department of Chemistry, Government Arts College, C.Mutlur, Chidambaram Received: Accepted: *Corresponding Author ABSTRACT The Experimental Internal pressure values have been evaluated for the Ternary and their sub-binary liquid mixtures of Benzene (1) +Hexane (2) +n-propanol (3) by using density, velocity and molar refraction from the temperature range of K to K. The experimental values of internal pressure for binary liquid mixtures were correlated through an equation proposed by Andiappan et al. The Experimental values of internal pressure for ternary liquid mixture were correlated through an equation proposed by us. Experimental values and the theoretical values agree so closely. Key words: sub-binary, Internal pressure, liquid mixtures, Benzene, Hexane, n-propanol INTRODUCTION Address: Name: N. Santhi Place: Tamilnadu, India nsaanthi@gmail.com INTRODUCTION 36

2 INTRODUCTION The most important fundamental factor in the theory of liquid state is the internal pressure and its correlation with other properties. Internal pressure deals with the forces of attraction and repulsion between the molecules in a liquid 1. Internal pressure is a measure of cohesive forces which are the basis for any model of a liquid and they are mainly responsible for the important physical properties of the liquids 2. Internal pressure being a measure of cohesive forces acting in a liquid is sensitive to change of temperature, concentration and external pressure 3. Internal pressure is determined by using ultrasonic velocity in conjucation with other thermodynamic measurable parameters 4. Haward 5, Parker 6, and Barton 7, brought out the fundamental significance of internal pressure. Acoustic and thermodynamic parameter such as Internal pressure is used to understand different kinds of association, the molecular packing, molecular motion and various types of intermolecular interactions and their strengths, influenced by the size in pure components and in the mixtures 8. The intermolecular interactions influence the structural arrangements along with the shape of the molecules 9. Srinivasan et al 10 derived from statistical thermodynamic considerations, a relation between the vapour pressure and internal pressure of a liquid and tested it for 30 polar and non-polar liquids. However very little work exists bringing out the importance of internal pressure in solutions. Collin et al 11 used thermodynamic and ultrasonic measurements to determine the internal pressure of liquids. The variation in internal pressure of binary liquid mixtures of aprotic, protic and associating liquids with changing composition of the mixture as well as with variation in temperature, have been investigated by several workers S.C.Srivastava and N.Berkowitz 17 was used to compute internal pressure from the measurement of ultrasonic velocity, density and molar Refraction. MATERIALS AND METHODS The liquids were purified as and when required as per the procedure recommended by Weissberger 18. Analar grade benzene supplied by B.D.H, India and guaranteed. Reagent grade n-hexane of Japan product was redistilled after drying with sodium. The fraction boiling at 80.1 C and 68.7 C respectively were collected and stored. Guaranteed reagent grade n- propanol was treated with calcium chloride and distilled. The fraction distilling at 97.1 C was collected. The Physical constants of pure liquids are given in the table. Liquid Density(g/cm 3 ) Boiling point( C) 30 C 25 C 30 C 25 C Exp Lit Exp Lit n-hexane Benzene n-propanol Ultrasonic velocities of pure liquids and liquid mixtures from the temperature range of 30 C to 45 C were measured using an ultrasonic interferometer operating at 3MHZ. The density was determined at the experimental temperature using 10 ml capacity specific gravity bottle immersed in a thermostatic bath (accuracy+0.01 C). The volume of the bottle at the experimental temperature, viz. 30 C-45 C was ascertained using doubly distilled water. The densities of water at these temperatures were obtained from literature. Theory and calculation: The Internal pressure for pure liquids and Mixtures at different temperatures were calculated using the equations (1) and (2). Relationship between Internal pressure and Molar refraction. 37

3 U = K' Pi (1) Where U=Ultrasonic velocity; D = Density; Rm = Molar refraction; K' = distinctly structure dependent Constant; Pi = Internal pressure If the data for ultrasonic velocity, density, Molar refraction, internal pressure is known, the constants for pure liquids can be determined.. For Binary Liquid Mixtures, Equation 1 is written as (Pi) 12= U /(x 1K 1' + x 2K 2') (2) Where, U =Ultrasonic velocity; D = Density; Rm = Molar refraction; x 1 and x 2 are Mole fractions; K 1' and K 2' are distinctly structure dependent constants; Pi = Internal pressure. Suryanarayana and Kuppusamy 19 derived an expression to account for the variation of internal pressure with concentration of the electrolyte which is of the form, internal pressure of π = π 0 + Am 2 + Bm (3) Where, π = internal pressure of the solution; π 0 = internal pressure of the solvent; m = molality A and B are constants which are temperature dependent because of in adequacies of expression (3). The above equation (3) is modified by Andiappan et al is as follows log π = x 1logπ 1 + x 2logπ 2 βx 1x (4) Where x 1 and π 1 are the mole fraction and internal pressure of the component 1 and x 2 and π 2 are those of the component 2. The equation (4) containing only one constant β, has been correlating the experimental data. In the present work, the extention of equation (4) for ternary system is attempted and the equation is written in the modified form. log π = x 1logπ 1 + x 2logπ 2 + x 3logπ 3 + x 1x 2(β 12(x 1-x 2)) + x 2x 3(β 23(x 2-x 3)) + x 3x 1(β 31(x 3-x 1)) - Cx 1x 2x (5) Where, β 12 = binary interaction constant for 1, 2 component; β 23 = binary interaction constant for 2, 3 component; β 31 =binary interaction constant for 3, 1 component; The constants β 12, β 23 and β 31 are determined from equation (4) and the constant C from equation (5). Equation (5) containing the above constants have been employed for correlating the experimental data. RESULTS AND DISCUSSION The Internal pressure values evaluated for the Ternary and sub-binary systems from the temperature range of K to K have been correlated through equations (4) and (5) is shown in Tables (1& 2). The tables (1 & 2) represent both the Experimental and Theoretical Internal pressure values. It is known from the tables that both the experimental and theoretical internal pressure values are more comparable with each other. The Interaction constants β and C are evaluated by using least square Method from the temperature range of K to K. In all the binary systems the absolute average deviation between the experimental and correlated values varies from 0.12% to 0.32%. The Interaction constant evaluated for all the binary systems varies from 0.04 to 0.1. From the tables (1& 2) it is evident that the internal pressure values increases with increase of alcohol concentration. Probably because at higher alcohol concentration hydrogen bonding becomes predominant resulting in the increase of internal pressure values

4 Table 1: Experimental and Calculated Internal pressures(in atm) System -Benzene(1)+Hexane(2) Mol Frac K K K K x1 EXP CAL EXP CAL EXP CAL EXP CAL ß= ß= ß= ß= % % % % System-n-propyl alcohol(1)+hexane(2) Mol Frac K K K K x1 EXP CAL EXP CAL EXP CAL EXP CAL ß= ß= ß= ß= % % % System-n-propyl alcohol(1)+benzene(2) % Mol Frac K K K K x1 EXP CAL EXP CAL EXP CAL EXP CAL ß= ß= ß= ß= % % % % 39

5 Table 2: Experimental and Calculated Internal pressures(in atm) for the system-benzene(1)+hexane(2)+npropanol(3) Mol Frac K K K K x1 x2 Exp Cal Exp Cal Exp Cal Exp Cal C= C= C= C= % % % % It is evident from the tables (1& 2), that the internal pressure values decreases with increase of temperature in all the cases. (i.e.) the cohesive forces decrease with increase of temperature 21. The variation of internal pressure with respect to the concentration and Temperature is given by graphical method. Figures (1-3) shows a linear variation of internal pressure with the concentration for binary liquid mixtures from the temperature range of K to K. 40

6 Figure 1: Figure-2: Figure 3: 41

7 Figures (4-6) shows a linear variation of internal pressure with the reciprocal of temperature for binary liquid mixtures from the temperature range of K K. Figure 4: Figure-5: Figure 6: 42

8 In the Ternary system the absolute average deviation between the experimental and correlated values varies from 1.48% to 1.79%. The Interaction constant evaluated for the Ternary system varies from 0.88 to CONCLUSION From the present work, it is evident that the absolute average deviation between the experimental and correlated values for the Binary system and Ternary system varies from 0.12% to 1.79%, indicating the applicability of equations (4) and (5). The variation of internal pressure with mole fraction or with temperature is quantitative, if the internal pressure is taken as the fundamental property. In the study of liquid mixtures, the variation of internal pressure can give information regarding the nature and strength of the forces existing between the molecules. REFERENCES 1. N.Prasad, Acustica, 171, (1991). 2. S.Rajagopalan and Surendra A. Tiwari, Acustica, vol, 66,(1998). 3. Suryanarayana, C.V. and Kuppusamy, J., Journal Acous. Soc., India, 4, 75 (1976). 4. B.P.Shukla and V K Jha and G P Dubey, Indian journal of pure and Applied 5. Physics, Vol.30, pp, , December (1992). 6. Haward, R.N. Trans Faraday Soc.62, 828(1966). 7. Haward, R.N.and Parker, B.M. J.Phy.Chem.Ithaca, 72, 1842 (1961). 8. Barton, A.F.M. J.Chem.Edn.48, 156 (1971). 9. T Sumathi* & J Uma Maheshwari, Indian Journal of pure & Applied Physics, Vol.47, pp , November (2009). 10. S.Prakash.J.Singh and S.Srivastava (Rm), Acustica, Vol 65,(1988). 11. G.M Srinivasan, G.A.Savariraj and C.V.Suryanarayana.Ind.J.Phys.52A, 23 (1978). 12. Collins, F.C. Brandit, W. W. and Navid M. H., J.Chem. Phys. 25(1956), Kuppusamy, J.and Suryanarayana, C.V., J.Acoustic.Soc.India, 4,103 (1977). 14. Sabesan, R., Natarajan, M. nd Sargurumoorthy, M., J.Acoust.Soc.India, 8, 2, 20(1980). 15. Dhanalakshmi, A., J. Acoust.Soc.India, 8, 2, 29(1980). 16. Prasad, N., Sivanarayana, K., Prakash, O. ND Prakash.S. Acoustics Letters, 5,4, 14(1981). 17. Prakash, S., Prasad, N. and Prakash, O., Ind.J.Phys. 50,801(1976). 18. S.C.Srivastava and N.Berkowitz, Canadian Journal of Chemistry, 41, (1963). 19. Weissberger, A Technique of organic chemistry Vol.7 (2 nd edn), Interscience Newyork., (1955). 20. C.V.Suryanarayana & J. Kuppusamy, J.Acoust.Soc (India), 9(1) (1981). 21. G.Amirthaganesan, S.Govindasamy & An Andiappan*, Indian Journal of chemistry, November 1986, Vol 25A, pp Hildebrand J H & Scott R L, Solubility of non-electrolytes (Reinhold, New York)