Excess molar volumes, isentropic and isothermal compressibilities, and isochoric heat capacities of (acetonitrile + benzene), (benzene + dimethylformamide), and (acetonitrile + dimethylformamide) at the temperature 298.15 K

Abstract

Densities ρ and speeds of sound u of {xCH3CN + (1 − x)C6H6}, {xC6H6 + (1 − x)HCON(CH3)2}, and {xCH3CN + (1 − x)HCON(CH3)2} were measured at the temperature 298.15 K. Excess molar volumes VEm and excess isentropic compressibilities kES of the mixtures were estimated from the results. Excess isothermal compressibilities kET and excess isochoric molar heat capacities CEV, m of the mixtures were also estimated from the measurements and the previous isobaric molar heat capacities Cp, m. VEm{xCH3CN + (1 − x)C6H6} changes sign from negative to positive with increase of x, VEm{xC6H6 + (1 − x)HCON(CH3)2} and VEm{xCH3CN + (1 − x)HCON(CH3)2} are negative over the whole composition range. kES and kET of the mixtures are in the similar trend to the corresponding VEm. CEV, m{xCH3CN + (1 − x)C6H6} changes sign from positive to negative with increase of x, and CEV, m{xC6H6 + (1 − x)HCON(CH3)2} is negative with a small positive region at x > 0.95. CEV, m{xCH3CN + (1 − x)HCON(CH3)2} is negative over the whole range, though CEp, m is complicatedly dependent on x.