Dielectric and physiochemical study of binary mixture of nitrobenzene with toluene Ajay G. Mohod, S. D. Deshmukh, K. L. Pattebahadur, P. B. Undre, S. S. Patil, and P. W. Khirade
Citation: AIP Conference Proceedings 1953, 050069 (2018); doi: 10.1063/1.5032724 View online: https://doi.org/10.1063/1.5032724 View Table of Contents: http://aip.scitation.org/toc/apc/1953/1 Published by the American Institute of Physics
Dielectric and Physiochemical Study of Binary Mixture of Nitrobenzene with Toluene Ajay G. Mohod a), S. D. Deshmukh, K. L. Pattebahadur, P. B. Undre, S. S. Patil and P. W. Khirade Microwave Research Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad – 431004 (M.S.) India. a)
Corresponding author:
[email protected]
Abstract. This paper presents the study of binary mixture of Nitrobenzene (NB) with Toluene (TOL) for eleven different concentrations at room temperature. The determined Dielectric Constant (ε0) Density (ρ) and Refractive index (nD) values of binary mixture are used to calculate the excess properties i.e. Excess Dielectric Constant (ε0E), Excess Molar Volume (VmE), Excess Refractive Index (nDE) and Excess Molar Refraction (RmE) of mixture over the entire composition range and fitted to the Redlich-Kister equation. The Kirkwood Correlation Factor (geff) and other parameters were used to discuss the information about the orientation of dipoles and the solute-solvent interaction of binary mixture at molecular level over the entire range of concentration.
INTRODUCTION Many chemical, pharmacological and other industries need to know physical properties of non-ideal mixtures which could be involved in process design [1]. Several binary liquids system parameters are used to investigate and interpret the medium effects in chemical reaction and molecular interactions [2-4]. The investigation of physical and dielectric properties of binary mixture provides valuable information about intermolecular interactions and dynamics of molecules at molecular levels [5, 14]. When a binary mixture is formed, the excess properties do not vary linearly [6]. The deviation of these parameters from the linear behaviour is considered to be very important and helps to find the nature of bonding between the two liquids [7]. In the present binary mixture, nitrobenzene is one of the component of particular interest because nitro group is highly polar and can associate with any other group having some degree of polar attractions [8]. Toluene is an aromatic compound, moderately polar due to hyper conjugation effect, mixed with nitrobenzene. The objective of this paper is to study interaction in Nitrobenzene (NB) – Toluene (TOL) mixture for different 11 concentrations at room temperature. The physiochemical properties of mixture, viz. Dielectric Constant, Density, Refractive Index, Molar Volume and Molar Refraction are also find out. Using these parameters, excess parameters of this system i.e. Excess Dielectric Constant, Excess Molar Volume, Excess Refractive Index and Excess Molar Refraction have been determined. Kirkwood correlation factor is also calculated to find out the information regarding orientation of electric dipoles in the binary mixture.
MATERIALS AND METHODS AR grade chemicals Nitrobenzene and Toluene were obtained commercially and used without further purification. The solutions were prepared at different volume percentages from 0% to 100% with increase in step of 10% volume percentage of Nitrobenzene (NB) in Toluene (TOL), at room temperature using micropipette. The detailed explanation of the apparatus and procedures is the same as described elsewhere [9, 10].
2nd International Conference on Condensed Matter and Applied Physics (ICC 2017) AIP Conf. Proc. 1953, 050069-1–050069-4; https://doi.org/10.1063/1.5032724 Published by AIP Publishing. 978-0-7354-1648-2/$30.00
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RESULT AND DISCUSSION The estimated values of Dielectric Constant (ε0), Density (ρ), Molar Volume (Vm) Refractive index (nD), and Molar Refraction (Rm) are obtained for Nitrobenzene-Toluene binary mixture with increase in volume percentage of Nitrobenzene in Toluene at room temperature are reported in Table 1. TABLE 1. The variation of Dielectric Constant (ε0), Density (ρ), Molar Volume (Vm) Refractive Index (nD), Molar Refraction (Rm) and Kirkwood Correlation Factor (geff) of NB-TOL binary mixture. Volume Fraction ε0 ρ Vm nD Rm geff of NB in TOL
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
2.43 4.24 6.42 9.23 12.19 14.52 18.25 22.21 26.01 30.83 34.25
0.8566 0.9118 0.9348 0.9698 0.9900 1.0344 1.0632 1.0970 1.1238 1.1674 1.2034
107.56 104.44 105.18 104.57 105.56 104.02 104.11 103.72 104.00 102.76 102.26
1.490 1.496 1.503 1.508 1.514 1.520 1.525 1.530 1.537 1.543 1.548
31.09 30.51 31.09 31.17 31.78 31.62 31.90 32.03 32.47 32.39 32.47
1.1312 0.7271 0.7245 0.7763 0.8057 0.7813 0.8331 0.8773 0.8998 0.9490 0.9471
The dielectric constant is dependent on the number of dipoles per unit volume. From the table 1, it is observed that ε0, and nD increases with increase in volume fraction of NB in TOL. From the obtained values of density and refractive index, molar volume and molar refraction are calculated. Molar volume gets decreases with increase in values of density of NB-TOL mixture. Molar refraction is directly related to the refractive index, so when the values of refractive index increases molar refraction also get increases with increase in volume fraction of NB in TOL. The excess parameters such as excess dielectric constant, excess molar volume, excess refractive index and excess molar refraction of the mixture are calculated using eq. (1) [11]. AE = Amix – (A1X1 + A2X2) (1) E where, A represents excess dielectric constant, excess molar volume, excess refractive index and excess molar refraction. A1, A2, and Amix represent the dielectric constant or molar volume or refractive index or molar refraction of pure liquids 1, 2 and mixture respectively. The X1 and X2 represents the volume fraction of component 1 and 2 of the mixtures respectively. The variation in excess dielectric constant (ε0E), excess molar volume (VmE), excess refractive index (nDE) and excess molar refraction (RmE) with volume fraction of NB in TOL at room temperature is presented in Fig. 1 a) Fig. 1 b) Fig. 1c) and Fig. 1 d) respectively.
(a)
(b)
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(c)
(d)
FIGURE 1. (a) Excess Dielectric Constant, (b) Excess Molar Volume, (c) Excess Refractive index, (d) Excess Molar Refraction of Binary mixture of NB-TOL.
The excess or deviation properties were fitted to the Redlich-Kister equation to calculate the bj values at various concentrations and used to draw the smooth curves [12]. The estimated values of bj coefficients at 95% confidence interval are presented in Table 2. TABLE 2. bj coefficients of excess parameters of NB-TOL binary mixture Excess b0 b1 b2 b3 parameters
ε0E nDE VmE RmE
1.2485 0.0017 2.8856 0.8854
4.9082 0.0068 11.3436 3.4806
5.7503 0.0080 13.2900 4.0778
12.7844 0.0178 29.5470 9.0660
The excess dielectric constant (ε0E) provides qualitative information about structure formation in the mixture as follows: [13] (i) ε0E = 0: indicates that the solute and solvent do not interact at all. (ii) ε0E < 0: indicates that the solute and solvent interaction act so as to reduce total effective dipoles. This suggests that the solute-solvent mixture may form multimers leading to the less effective dipoles. (iii) ε0E > 0: indicates that the solute and solvent interact in such a way that the effective dipole moment increases. Dipoles aligned in parallel direction. There is formation of monomers and dimmers. From Fig. 1 a), ε0E values are negative for all concentrations. These negative values indicate that the molecules of NB-TOL mixture may form multimer structures in such a way that the total effective dipoles get reduced and dipoles align in antiparallel direction. Figure 1 b) shows negative values of VmE over the entire concentration range (except for volume fraction 0.8) of NB-TOL mixture. The negative values of VmE indicate contraction of volume after mixing of two liquids due to strong intermolecular interaction in NB-TOL mixture. The values of nDE observed positive with increase in concentration of NB in TOL are shown in Fig 1 c). In this study, RmE values are negative (except for volume fraction 0.8) in NB-TOL mixture shown in Fig. d). RmE plot shows similar nature as of VmE. Thus result arrived from excess molar refraction supported to result of excess molar volume. The Kirkwood correlation Factor (geff) [14] is a parameter containing information regarding orientation of electric dipoles in the binary mixture. The values of geff are given in the Table 1 for NB-TOL mixture. The value of geff for pure toluene is greater than unity (i.e 1.1312) which indicates a high degree of coordinated chain like structures with parallel orientation of electric dipoles and the geff value for pure nitrobenzene is less than unity (i.e. 0.9471) indicates the antiparallel orientation of electric dipoles [15]. For the binary mixture of NB-TOL, the geff values are less than unity for all concentration is resemblance to negative values of excess dielectric constant which confirms the antiparallel orientation of electric dipoles in NB-TOL binary mixture.
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CONCLUSION It is concluded from the study of NB-TOL mixture, that the dielectric and physiochemical properties were applied to find out the intermolecular interactions of binary liquid mixture of NB-TOL. The non-linear variation of Dielectric constant, density and refractive index is observed with the increase in concentration of Nitrobenzene in Toluene. If the molecules of binary mixture are interacting with each other, then there is a non-linear variation in these parameters expected and the same variation is observed in the present study. So from this study it is confirmed that the intermolecular association is present between the molecules of NB-TOL binary mixture. The deviation of excess parameters of NB-TOL system from zero also shows the presence of intermolecular interaction between the molecules of NB-TOL mixture. The excess dielectric constant shows antiparallel alignment of dipoles in NB-TOL mixture. Kirkwood correlation factor indicates antiparallel orientation of electric dipoles is resemblance to excess dielectric constant in NB-TOL mixture. The excess molar volume and excess molar refraction of NB-TOL mixture supported to each other. These results are useful for the interpretation of the nature of interactions.
ACKNOWLEDGMENTS The financial support from University Grant Commission New Delhi, under the Special Assistance Programme (SAP), is thankfully acknowledged (F.530/16/DRS-I/2016 SAP-I Dated 16 April 2016).
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