EXCESS GIBBS ENERGIES AND EXCESS-ENTHALPIES OF LIQUID BINARY-MIXTURESCONTAINING NITROALKANES

A head-space gas chromatographic technique was used to determine vapou r phase equilibria for binary mixtures of 1-nitroalkanes (1-nitropropa ne, 1-nitrobutane, 1-nitropentane) + n-heptane or cyclohexane. Excess molar Gibbs energies, G(E), for the mixtures investigated were obtaine d. All systems exhibit positive deviations. The G(E) values decrease w ith increasing nitroalkane chain length. Activity coefficients at infi nite dilution, gamma(i)infinity were also evaluated. A flow microcalor imeter, Model 2277-LKB, was used to determine excess enthalpies, H(E), as a function of concentration at atmospheric pressure and 298.15 K, for binary liquid mixtures containing the same 1-nitroalkanes with tet rachloromethane. A tentative approach, based on an additivity scheme o f surface interactions combined with the scaled particle theory, is pr esented to estimate and analyse group contributions to DELTAG(solv)0 a nd DELTAH(solv)0, the energy and the enthalpy of solvation respectivel y.