International Journal of Research and Innovation in Applied Science (IJRIAS) |Volume VIII, Issue I, January 2023|ISSN 2454-6194
Grace A. Cookey*, Ngozi J. Maduelosi, Brave L. Tambari
Department of Chemistry, Rivers State University, Port Harcourt, Nigeria
*Corresponding author
Received: 10 January 2023; Revised: 21 January 2023; Accepted: 01 February 2023; Published: 25 February 2023
Abstract: This study was designed to use survismeter to exploit the mixing behavior of a weak polar solvent (diethyl ether) and non-polar solvent (hexane) in varying compositions of diethyl ether and temperature. The densities and viscosities of binary mixed solvents of diethyl ether and hexane were evaluated at temperatures of 303, 313, 323 and 333 K and over varying compositions of diethyl ether using a single capillary pycnometer and Mansingh Survismeter respectively. The excess molar volumes (VE), excess viscosities (ɳE) and excess Gibb’s free energy (GE) of activation for viscous flow of the binary mixtures at the different temperatures were evaluated from the experimental parameters using Redlich Kister equation. The results show negative values of VE and GE at all mole fractions and temperatures. The ɳE values are positive at 303 and 313 K but negative at 323 and 333 K at all compositions respectively. These observations have been interpreted based on the molecular interactions between the components of the solvent mixtures and structural changes resulting from these interactions.
Keywords: Thermodynamics, Viscosity, Activation energy, Density.
I. Introduction
Solvents are used by scientists and engineers for chemical investigations and a variety of industrial processes. Therefore, good knowledge of the mode of interactions in different media and the effects of combining them in various compositions becomes very important. These solvent interactions depend on the nature or class of solvents studied i.e., whether protic, aprotic, polar or non-polar (Maduelosi and Abia, 2015). They can also be classified according to the acidity or basicity of the liquids or the ability to attract/repel hydrogen ions in solution.
Studies of excess thermodynamic properties of binary mixed solvents are important in the understanding of the nature of intermolecular interactions and flow rate properties associated with solvent mixtures and component liquids (Dikio et, al., 2012, Arvinds et, al., 2013, Dikio et, al., 2013, Lakshimi et al., 2014, Pandey et al., 2014 ). These excess functions provide the most sensitive numerical measure of solution properties of the pure solvents in original state (Welford- Abbey, et al 2009). They are also of theoretical and practical importance such as in Prigogine-Flory-Patterson theory, Nernst distribution equation, Calorimetry, titration, etc. (Baskaran et, al., 2010, Elliot and lira, 2012). The knowledge of excess functions is also very useful in dealing with chemical bifurcations, fluid flow and heat transfer processes (Pal and Kumar 2006, Saleh et al., 2006) which are applied in testing and designing thermodynamic models used in computing and prognosticating fluid phase equilibria.
Mixing of two solvents has been reported to catalyze specific interactions such as hydrogen bonding, dipole-dipole and ion-solvent interactions (Nallani and Jaana, 2008, Maduelosi et al.,2014). Strong and weak interactions between distinct molecular liquid mixtures cause deviations from ideality. This behaviour is usually consociated with large differences in the chemistry and molecular armature of the mixed solvents, the mixing ratios as well as the experimental fettles such as temperature (Salman et al., 2018). Structural changes such as hydrogen bond rupture and loosening of dipole interactions result in positive excess volumes, negative excess viscosities and Gibb’s free energies of activation respectively. On the other hand, molecular fitting into interstitial spaces and strong attractive interactions give rise to negative excess molar volumes, positive excess viscosities and Gibb’s free energy of activation for viscous flow.
In this research, experimental viscosities and densities of binary mixtures of diethyl ether and hexane are reported at different mole fractions of diethyl ether and temperatures of 303, 313, 323 and 333 K. These values were Fitted into Redlich Kister equation to generate the excess viscosities, excess molar volumes and excess Gibb’s free energy of activation for viscous flow.