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

Abstract

A flow microcalorimeter of the Picker design was used to measure excess molar enthalpies H E at 298.15 K of {x,C6H5F + xzn-C,Hzr+2) for 7, 8, 10, 12, 14 and 16. The calorimeter was used in the discontinuous mode. The actual mole fractions x, 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)/Hiax < 0.005, where s(HE) denotes the standard deviation from a Redlich-Kister type smoothing equation, and the subscript max indicates the maximum of H E 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. I = 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 I = 7, 8, 10, 12 and 14. In all cases S ( C~) / ( C ; , , ,~~( < 0.013, where min indicates the minimum of Cp". A preliminary discussion of the results is presented in terms of the simplest version of the Guggenheim-Barker-Kehiaian group-contribution theory.

Temperature Dependence of Densities and Speeds of Sound of Nitromethane + Butanol Isomers in the Range (288.15−308.15) K

“…Consequently, for all these mixtures if the alkyl chain of the nitroalkane increases, the excess properties decrease. This effect is also observed for other systems and might be due to the fact that, although in the gas phase the molecular dipole moments of the nitroalkanes are nearly the same (3.5 D), in the condensed liquid phase the effective polarity 18 is greater for the smaller nitroalkane. As the alkyl chain of the nitroalkane increases, the polar groups are more diluted and their interactions are therefore weakened.…”

New Batch Cells Adapted To Measure Saturated Heat Capacities of Liquids

“…heat capacity/(J·K -1 ·mol -1 )liquidexptllit. hexane 195.23 195.48 2 195.67 195.33 heptane 225.10 224.98 2 224.76 224.78 decane 314.88 314.54 2 315.46 314.21 dodecane 375.76 375.70 376.00 375.26 cyclohexane 156.09 156.01 2 156.03 156.1 benzene 135.58 135.76 2 135.707 135.64 toluene 157.15 157.29 2 157.15 157.057 methanol 81.26 81.47 2 81.92 81.04 13 1-butanol 177.21 177.08 2 2,5,8,11-tetraoxadodecane 368.01 367.78 …”

Excess molar enthalpies of (an alkanoic acid +n-heptane, or cyclohexane, or benzene) atT= 298.15 K

“…Excess molar enthalpies H E m were determined as previously (5,6,15,16) with a flow microcalorimeter of the Picker design (from Setaram, France) equipped with separators, and operated in the discontinuous mode. The calorimeter was thermostatted to about ±0.002 K as checked with a quartz thermometer.…”