Comparative study of physico-chemical properties of binary mixtures of N,N-dimethylformamide with 1-alkanols at different temperatures

Abstract

Densities ρ, refractive indices nD and speeds of sound u for binary mixtures of N,N-dimethylformamide (DMF) with 1-pentanol, 1-hexanol and 1-heptanol over the entire range of mole fraction were measured at T=(298.15, 303.15, 308.15 and 313.15)K and atmospheric pressure. Excess molar volumes VE, isentropic κS, excess isentropic compressibility κsE, deviations in speed of sound uD and excess refractive indices nDE for the above systems were calculated from the experimental data. The excess molar volume, excess isentropic compressibility and deviations in speed of sound were further fitted to the method of least square of the Redlich–Kister (R–K) polynomial. The speeds of sound have been analysed in term of Schaaffs’ collision factor theory (CFT), Jacobson’s intermolecular free length theory of solutions (FLT), Nomoto relation (NM) and Van Deal ideal mixture relation (IMR). The Lorentz–Lorenz (L–L), Dale–Gladstone (D–G), Eykman (Eyk) and Arago–Biot (A–B) mixing rules were used to predict the refractive indices of the binary mixtures. The calculated excess molar properties have been qualitatively used to explain the intermolecular interaction between the mixed components as well as the effects of n-alkan-1-ol chain length and the temperature on them.