Internal pressure and optical properties of binary mixture of formamide with dimethylaminoethanol and diethylaminoethanol at different temperatures

Abstract

The density (ρ) and refractive indices (n) of binary mixtures of formamide (FA) with dimethylethanolamine (DMEA) and diethylethanolamine (DEEA) have been recorded at different temperatures for the whole composition ranges. The experimental values of density data and refractive index are used to estimate the molar refraction (R_m), reduced molar free volume (V_m/R_m), molecular radii (r) and internal pressure (P_int). The deviations of refractive index (Δn_D), molar refractions (ΔR_m), reduced molar free volumes Δ (V_m/R_m) and internal pressures (ΔP_int) have been also calculated. The variations of these parameters with composition and temperature of the mixtures are discussed in terms of molecular interactions due to physical, chemical and structural effects between the unlike molecules. The applicability of different refractive index mixing rules is tested against the experimentally measured values and good agreement has been obtained.