J. D. Pandey

Ultrasonic speeds and isentropic compressibilities of ternary liquid mixtures at (298.15±0.01) K

Abstract Measurements of ultrasonic speed were carried out for (n-pentane + n-hexane + benzene), (n-hexane + cyclohexane + benzene), and (cyclohexane + n-heptane + toluene) at (298.15±0.01) K. The ultrasonic speeds of these mixtures were also evaluated theoretically from various empirical, semi-empirical, and statistical models. The agreement between theoretical and experimental values is fair for all the mixtures. An attempt has also been made to explain the nature of intermolecular interactions in the light of excess isentropic compressibilities.

Estimation of molecular radius of liquids and liquid mixtures from sound velocity

Abstract Various acoustic methods have been utilized to compute the molecular radius of pure liquids and liquid mixtures at varying conditions. The values thus obtained have been compared against the values obtained from a non-acoustic method, which uses refractive index data. These results have been utilized to study the relative merits of these various relations. An attempt to correlate the molecular radii of the liquids and liquid mixtures with other related properties of the liquid system has also been made. The applicability of an acoustic method like Schaaffs’ method for the computation of the molecular radius in liquid mixtures has also been authenticated.

Inversion of the Kirkwood–Buff theory of solutions: application to binary systems

Abstract Kirkwood–Buff (K–B) integrals play an important role in characterizing the properties and interactions of various liquid mixtures. However, there exists no method to calculate directly the K–B integrals from the easily available experimental data of ultrasonic velocity and density. An attempt has been made to evaluate the same using these initial parameters. A statistical mechanical theory advanced by Arakawa et al. has been used here, in combination with a semi-empirical formula to compute K–B parameters in the whole concentration range for six binary systems at atmospheric pressure and at 298.15 K.

Speed of sound, viscosity and refractive index of multicomponent systems: theoretical predictions from the properties of pure components

Abstract Theoretical prediction of speed of sound, viscosity and refractive index of three ternary systems: toluene + n-heptane + n-hexane (I), cyclohexane + n-heptane + n-hexane(II) and n-hexane + n-heptane + n-decane (III) have been made on the basis of empirical, semi-empirical and statistical mechanical theories using the properties of pure components. Theoretical results are compared with the experimentally measured values at 298.15 K.

Apparent molal volume, apparent molal compressibility, verification of jones-dole equation and thermodynamic studies of aqueous urea and its derivative

Abstract Ultrasonic, volumetric and viscometric measurements have been performed on urea and its derivatives at 25, 30, 35 and 40 ° C. These measurements have been used to evaluate some important ultrasonic and thermodynamic parameters, viz. apparent molal volume φ v , partial molal volume φ o v , apparent molal compressibility φ k , partial molal compressibility φ o k , viscosity B -coefficient of Jones-Dole equation, free energy of activation for viscous flow Δ G , entropy Δ S , and enthalpy of activation Δ H for viscous flow. These parameters have been used to interpret the results in terms of solute-solvent interactions. The structural interactions of urea and its derivatives with water molecules are interpreted successfullly.

Thermal expansivity of multicomponent liquid systems

Thermal expansivity of a number of binary and multicomponent molecular liquid mixture have been evaluated by applying various theoretical models viz. hard sphere and statistical mechanical theory. Formulism has been made. Computed values of thermal expansivity have been compared with experimental findings.

ULTRASONIC VELOCITY OF BINARY SYSTEMS AT ELEVATED PRESSURES

Various empirical theories of ultrasonic velocity have been applied to three binary liquid mixtures, under pressures up to 200 MPa and their validity have been tested. A pressure dependent study of ultrasonic velocities has been made at 303.15 K. The agreement between theory and experiment is found to be quite satisfactory.

Theoretical estimations of thermodynamic properties of liquid mixtures by Flory's statistical theory

Florys statistical theory has been employed for the computation of ultrasonic velocity (u), density (ρ), internal pressure (P i), thermal expansion coefficient (α), isothermal compressibility (β T), adiabatic compressibility (β S), heat capacity at constant pressure (C P), heat capacity at constant volume (C V), heat capacities ratio (γ), pseudo-Gruneisen parameter (Γ), excess volume (V E) and excess heat capacity at constant pressure ( ) at varying temperatures for 10 binary and 5 ternary systems. The binary systems under investigation are: acetonitrile + benzene, benzene + DMF, acetonitrile + DMF, cyclohexanol + cyclohexane, piperidine + tetrahydropyran, piperidine + cyclohexane, tetrahydropyran + cyclohexane, benzene + p-xylene, benzene + p-dioxan, acetone + methyliodide, and the ternary systems are: benzene + chloroform + cyclohexane, toluene + chloroform + cyclohexane, chlorobenzene + chloroform + cyclohexane, dioxane + chloroform + cyclohexane and chlorobenzene + cyclohexane + n-heptane. The results of calculations show that for all the systems under consideration, the calculated values of various thermodynamic parameters show the same trend as observed experimentally. Fairly good agreement is found between theoretical and experimental values. The ultrasonic velocity of liquid mixtures is obtained using the most popular Flory theory without the help of any empirical relation.

Internal pressure, ultrasonic velocity and viscosity of multi-component liquid systems

Ultrasonic velocity, density and viscosity were measured in two ternary liquid systems namely,n-pentane +n-hexane + benzene(I) andn-hexane + cyclohexane + benzene(II) and one quaternary liquid system,n-pentane +n-hexane + benzene + toluene (III). The experimental as well as literature values of thermal expansion coefficient and iso-thermal compressibility of pure liquid components were utilized to deduce the ideal value of internal pressure and excess internal pressure for the above liquid systems at 298·15K using two different approaches. In the conventional approach one needs the experimental values ofα andβT of mixtures for computing internal pressure, which was not possible. The second method which is proposed here utilizes only the density, ultrasonic velocity and viscosity data of the mixture. This method is used in computing internal pressure and its excess value for multicomponent liquid systems. A satisfactory agreement has been observed.

Excess internal pressures, excess free volumes and excess thermodynamic parameters of some non-aqueous binary mixtures from ultrasonic speed, density and viscosity data

The internal pressure, πi; free volume, V f; excess internal pressure, ; excess free volume, ; excess free energy, G E; excess enthalpy, H E and excess entropy, S E of mixing for the binary mixtures of tetrahydorfuran (THF) with benzene, toluene, o-xylene, m-xylene, p-xylene and mesitylene have been calculated from experimental ultrasonic speed, density and viscosity data over the whole composition range at 298.15 K. The results have been discussed in terms of intermolecular interactions between the component molecules in the mixture. The variations of these excess functions with composition indicate that the THF-aromatic hydrocarbon interaction in these mixtures follows the order: benzene > toluene > p-xylene > m-xylene > o-xylene > mesitylene. Further, πi of these binary mixtures are also evaluated theoretically by using various equations proposed in the literature. The results are compared with the experimental findings, and relative merits of these equations in predicting internal pressure are discussed.