Patrick J. D'Arcy

APPLICATION OF A FLOW MICROCALORIMETER TO DETERMINE THE EXCESS ENTHALPIES OF BINARY MIXTURES OF NON-ELECTROLYTES*

Abstract The performance of an LKB flow microcalorimeter has been improved through changes in the auxiliary equipment and operating technique. Measurements of excess enthalpies, precise to 0.5% or better, are reported for several test systems.

Thermodynamics of aqueous mixtures of nonelectrolytes II. Isobaric heat capacities of water-n-alcohol mixtures at 25°C

Excess isobaric heat capacities of binary mixtures of water with methanol, ethanol, and 1-propanol were obtained from flow microcalorimetric measurements at 25°C over the entire composition range. The results are compared with those of previous investigations.

Excess enthalpies and heat capacities for 2,5,8-trioxanonane + n-heptane mixtures☆

Abstract Flow calorimetric techniques were used to determine excess enthalpies and volumetric heat capacities of 2,5,8-trioxanonane + n -heptane mixtures at 25°C. The molar excess enthalpies are positive over the entire mole fraction range. The molar excess isobaric heat capacities are negative and exhibit a maximum and two minima.

Excess enthalpies and heat capacities for (di-n-propylether + n-heptane)☆

Excess molar enthalpies HmE, and excess molar isobaric heat capacities Cp, mE are reported for (di-n-propylether + n-heptane) at 298.15 K. The results, in combination with those of a previous investigation of the volumes of the same mixture, were used to calculate excess molar isochoric heat capacities, excess isentropic compressibilities, excess isothermal compressibilities, and the differential coefficient (∂HmE∂p)T.

Thermodynamics of aqueous mixtures of nonelectrolytes. V. Isobaric heat capacities and ultrasonic speeds for water + ethanenitrile mixtures at 25°C

Abstract Volumetric heat capacities and ultrasonic speeds were measured at 25°C for water + ethanenitrile mixtures over the entire mole fraction range using a flow microcalorimeter and pulse-echo-overlap equipment, respectively. Excess volumes and coefficients of thermal expansion reported previously were used in conjunction with the present data to yield isobaric and isochoric heat capacities, and isentropic and isothermal compressibilities. The present study supports the view that ethanenitrile acts as a structure breaker.

Partial molar volumes of gases dissolved in liquids. Part II. A dilatometer for measuring infinite-dilution partial molar volumes, and results for 40 liquid-gas systems☆

Abstract A dilatometer with an imprecision of less than 0.4% is described for the determination of partial molar volumes of gases dissolved in liquids. Measurements at 298.15 K are reported for 40 liquid-gas systems having n-alkanes and 1-alkanols as the liquid component. The results are interpreted in terms of a number of empirical and semiempirical correlations.

Thermodynamic properties for 2, 5, 8, 11-tetraoxadodecane + n-dodecane mixtures at 298.15 K

Abstract Flow calorimetric measurements of the excess molar enthalpy and excess molar isobaric heat capacity, dilatometric measurement of the excess molar volume, and pulse-echo-overlap determinations of the speed of sound were carried out over the whole composition range for mixtures of 2,5,8,11-tetraoxadodecane with n -dodecane at 298.15 K. The excess molar enthalpy and excess molar volume are positive at all mole fractions. The speed of sound shows negative deviations from linearity on a mole fraction basis. The excess molar isobaric heat capacity exhibits a maximum and two minima.

Excess isobaric heat capacities of some binary mixtures: (a C5-alkanol+n-heptane) at 298. 15 K

Abstract Excess molar isobaric heat capacities, determined at 298.15 K in a low microcalorimeter, are reported for n-heptane + each of the C5-alkanols: pentan-1-ol, cyclopentanol, and 2-methylbutan-2-ol. Over most of the mole-fraction range, the excess molar isobaric heat capacities are positive. However, small negative values were found for low mole fractions of alkanol. This behavior is discussed in terms of the auto-association of the alkanol.

Heat capacities of binary mixtures of n-heptane with hexane isomers☆

Abstract Volumetric heat capacities were measured for binary mixtures of n -heptane with n -hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane at 298.15 K in a Picker flow microcalorimeter. The results were combined with previously published excess molar volumes to obtain excess molar isobaric heat capacities. Use of the Flory theory of mixtures to interpret the latter is discussed.

Excess enthalpies and heat capacities for 3,6-dioxaoctane + n-heptane mixtures☆

Abstract Flow calorimetric measurements of excess enthalpies and excess isobaric heat capacities are reported for 3,6-dioxaoctane + n -heptane mixtures at 298.15 K. Throughout the composition range, the excess enthalpies are positive and the excess heat capacities are negative. The excess enthalpies are compared with the results of calculations using a model involving group surface interactions.