Ultrasonic studies of formamide plus 1,2-ethanediol and sodium iodide plus formamide plus 1,2-ethanediol mixtures at 298.15 K

Densities (rho) and ultrasonic velocities (u) of pure formamide (FA), 1,2-ethanediol, their binary mixtures and those of sodium iodide (0.05, 0.10, 0.20 M) in FA + 1,2-ethanediol binary mixtures have been measured as a function of FA mol fraction, x at 298.15 K. Ultrasonic velocities of binary and ternary mixtures have been fitted by empirical equation. From these experimental data adiabatic compressibility (beta), intermolecular free length (L-f), excess adiabatic compressibility (beta(E)), excess intermolecular free length (L-f (E)), excess volume (V-E) of FA + 1,2-ethanediol while beta, L-f and relative association (R-A) of NaI + FA + 1,2-ethanediol mixtures are computed as a function of x. Positive excess properties over the whole composition range of binary mixtures indicate weak interactions between the component molecules.