Molecular Interaction Study of Glycine in Aqueous Lactose Solution Using Volumetric, Acoustic and Viscometric Methods at Different Temperatures

Abstract

Density, viscosity, sound speed and refractive index of glycine in aqueous lactose solution at varying concentrations from 0.1035 to 1.0345 m at 298, 308, and 318 K have been determined using precalibrated bycapillary pycnometer, Ostwald’s viscometer and single frequency ultrasonic interferometer at 2 MHz frequency respectively. The derived acoustic parameters like apparent molal volume( ), apparent molal compressibility( ), specific acoustic impedance (Z), intermolecular free length (L_f),  acoustical relaxation time ( ), relative association (R_A), free volume (V_f), absorption coefficient (α/f²), adiabatic compressibility (β), hydration number (n_H), Gibbs free energy (ΔG), internal pressure (π_i), Rao’s constant (R_m), Wada’s constant (W), limiting apparent molal volume(f_v^o), limiting apparent molal compressibility(f_k^o), Jones-Dole coefficient (B), Falkenhagen coefficient (A) and molar refractivity (R_D) have been calculated from experimental data. All measurements have been carried out in a thermostatic controlled refrigerated water bath with circulating medium with an accuracy of ± 0.1 º C. As the temperature increases, solute solvent interactions also increase. Positive values of B coefficient also suggest that glycine is a structure maker at the investigated temperatures.

Keywords: Lactose, glycine, water, viscosity, refractive index