Shashi Singh

Mixing properties and modelling of methanol with chlorobenzene and bromobenzene at 293, 303, and 313 K

Refractive index, ultrasonic velocity and density for the binary mixtures of methanol with chlorobenzene and bromobenzene at 293, 303, and 313 K have been measured over the entire composition range. The values of refractive index (n), ultrasonic velocity (u), and density (ρ) were used to compute deviation in molar refraction (ΔR m) and deviation in isentropic compressibility (Δκ s). The results of deviation were fitted to the Redlich–Kister polynomial equation to derive the binary coefficients and standard deviation. Both the systems exhibited negative values of ΔR m and Δκ s over the entire composition range. The density, ultrasonic velocity and refractive index were correlated to first order polynomial with respect to mole fraction. Experimental data of physical properties (refractive index, isentropic compressibility and density) were compared with the results obtained by theoretical estimation procedures.

Thermoacoustical response of 1,4-dioxane with carboxylic acids

Experimental values of ultrasonic velocity (u), density (ρ), refractive index (n) and viscosity (η) for the binary mixtures of 1,4-dioxane with acetic acid and propionic acid have been measured at 293, 303 and 313 K over the entire mole fraction range. Using these data, the excess adiabatic compressibility , deviation in viscosity (Δη), excess intermolecular free length , molar compressibility (B), molecular radius (r m), relaxation strength (r), and van der walls constant (b) have been calculated. These parameters were used to study the nature and extent of intermolecular interaction between component molecules present in the binary mixtures. Excess values of βs and η were plotted against the mole fraction of 1,4-dioxane over the whole composition range. The values of , Δη and for two binary mixtures have been found to be negative which suggest the presence of weak molecular interaction in these mixtures. Molecular radius (r m) and relaxation strength (r) of liquid mixtures were also evaluated since these parameters are useful in prediction of molecular properties of liquid mixtures.

Thermoacoustical study of molecular interactions in binary mixtures of pentane with methanol and tert-butanol

Experimental values of density, ultrasonic velocity and viscosity for the binary mixtures of pentane with methanol and tert-butanol have been measured at 293.15, 298.15 and 303.15 K over the entire composition range. Using these experimental data, specific heat ratio, heat capacity, effective Debye temperature, pseudo-Grüneisen parameter, viscosity deviation, excess internal pressure, excess Gibbs free energy of activation for viscous flow and excess molar enthalpy have been calculated and computed results were fitted to the Redlich-Kister polynomial equation. These parameters were used to study the nature and extent of intermolecular interaction between components molecules present in the binary mixtures. The results suggest that stronger specific interactions are taking place in pentane + methanol mixture than in pentane + tert-butanol mixture. Furthermore, various empirical relations were used to correlate the ultrasonic velocities of these mixtures. An excellent agreement has been found between experimental and theoretical values.

Thermodynamic and acoustic properties of binary mixtures of PEGDME 250 with 1-propanol and 1-butanol at 293, 303 and 313°K

ABSTRACT The work presented in this paper deals with the study of thermodynamic properties of new working fluids for absorption machines, mainly for characterisation of absorbent–refrigerant pairs that could improve the cycle performance. The study of atomic motion in liquids plays an important role in understanding the solid-like behaviour of liquids. The accurate measurement of the energy changes due to scattering can be used to study the dynamical behaviour of liquids. Measurements of the ultrasonic velocity (u), density (ρ) and viscosity (η) for binary mixtures of polyethylene glycol 250 dimethyl ether with 1-propanol and 1-butanol have been made at three temperatures (T = 293, 303 and 313 K) over the entire composition range in order to investigate the nature of intermolecular interactions between the components of these liquid mixtures. Non-linear variation of derived quantities with the mole fraction supports the molecular interaction occurring between component molecules.