Excess Molar Enthalpies, Excess Molar Heat Capacities and Excess Molar Volumes of (Fluorobenzene + an n‐Alkane)

Abstract

AbstractA flow microcalorimeter of the Picker design was used to measure excess molar enthalpies HE at 298.15 K of {x1C6H5F + x2n‐ClH2/+2} for l = 6, 7, 8, 10, 12, 14 and 16. The calorimeter was used in the discontinuous mode. The actual mole fractions x1 were determined with the aid of a vibrating‐tube densimeter connected to the outlet of the mixing cell in conjunction with density data measured separately. The imprecision of the measurements is characterized by s(HE)/H < 0.005, where s(HE) denotes the standard deviation from a Redlich‐Kister type smoothing equation, and the subscript max indicates the maximum of HE with respect to composition. At the same temperature and for the same mixture, excess molar volumes VE were determined with a vibrating‐tube densimeter (flow conditions). With one exception (i.e. l = 6), s(VE)/V < 0.007. Another type of flow calorimeter was used to measure excess molar heat capacities C at constant pressure of mixtures belonging to the same series with l = 7, 8, 10, 12 and 14. In all cases s(C)/CP,minE < 0.013, where min indicates the minimum of C. A preliminary discussion of the results is presented in terms of the simplest version of the Guggenheim‐Barker‐Kehiaian group‐contribution theory.