Carl J. Halpin

Excess enthalpies of binary mixtures of n-heptane with hexane isomers

Abstract Molar excess enthalpies, measured in a flow microcalorimeter, are reported for binary mixtures of n -heptane with the five isomeric hexanes. For equimolar mixtures at 298.15 K, deviations from ideality range from 0.46 J·mol −1 for n -hexane to 23.16 J·mol −1 for 2,2-dimethylbutane.

Ultrasonic speeds and isentropic compressibilities for (decan-1-ol + n-alkane) at 298.15 K☆

Measurements of ultrasonic speed were carried out for hexan-1-ol+n-pentane, +n-hexane, +n-octane, and +n-decane at 298.15 K. The measurements were made over the entire mole-fraction range with special attention paid to the region highly dilute with respect to hexan-1-ol. The results were combined with excess volumes VmE from our previous studies to yield excess isentropic compressibilities KSE and the partial molar excess quantities KS.iE = −(∂ViE∂p)s. A qualitative discussion of the results is presented.

Ultrasonic velocities, compressibilities, and heat capacities for binary mixtures of benzene, cyclohexane, and tetrachloromethane at 298.15 K☆

Abstract Ultrasonic velocities in binary mixtures of benzene, cyclohexane, and tetrachloromethane were determined at 298.15 K over the whole mole fraction range using a pulse-echooverlap method in a successive dilution cell. The results were combined with auxiliary information from the literature to obtain isentropic and isothermal compressibilities, and heat capacities at constant volume. The excess values of these properties are compared with previously published results.

Excess volumes and isentropic compressibilities for (2-ethoxyethanol + n-heptane) at 298.15 K

Abstract Excess volumes and ultrasonic speeds have been measured for (2-ethoxyethanol + n-heptane) at 298.15 K. Isentropic compressibilities, excess isentropic compressibilities, and the partial molar excess quantities K S, i E = −( ∂V i E ∂p ) S were calculated from the results. The excess volume is positive over the entire mole-fraction range, whereas the curves for the excess isentropic compressibility is sigmoid with negative values occurring at mole fractions of 2-ethoxyethanol greater than 0.35. A qualitatitive interpretation of the results is presented.

Excess volumes and ultrasonic speeds for (di-n-propylether + n-heptane)

Excess molar volumes VmE, at 288.15, 298.15, and 308.15 K, and ultrasonic speeds at 298.15 K are reported for (di-n-propylether + n-heptane). From the results, the differential coefficients (∂VmE∂T)p and (∂VmE∂p)s were estimated over the entire mole-fraction range.

Ultrasonic speeds and isentropic compressibilities of n-heptane +each of the hexane isomers at 298.15 K

Abstract Measurements of ultrasonic speed were carried out for n-heptane + each of the five isomeric hexanes at 298.15 K. The results were combined with excess volumes reported previously to obtain isentropic compressibilities and excess isentropic compressibilities. Values of the latter are in reasonable agreement with estimates from the Flory theory of mixtures.

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.

Ultrasonic speeds and isentropic compressibilities of each of the mixtures: (2-ethylbutan-1-ol+an isomer of hexane) at 298.15 K

Abstract Ultrasonic speeds were determined for each of the five mixtures: (2-ethylbutan-1-ol + an isomer of hexane). Measurements were made over the whole mole-fraction range with particular attention given to the region of high dilution with respect to the alcohol. The results were combined with previously reported excess molar volumes to obtain isentropic compressibilities and values of the excess molar quantity K S,m E = −(∂V m E ∂p) S .

Excess volumes and ultrasonic speeds for (3,6-dioxaoctane+n-heptane)

Abstract Excess molar volumes VmE and ultrasonic speeds are reported for (3,6-dioxaoctane + n-heptane) at 298.15 K, and are used to calculate isentropic compressibilities and the differential coefficients ( ∂V m E ∂p ) s . The results are compared with those obtained previously for other (ether + n-heptane) mixtures and their interpretation in terms of the Flory theory is examined.

Limiting excess partial molar enthalpies of hexan-1-ol, 2-methylpentan-1-ol, and 2-ethylbutan-1-ol in n-hexane at 298.15 K

Abstract Excess molar enthalpies of { x CH 3 (CH 2 ) 5 OH+(1− x )C 6 H 14 }, { x CH 3 (CH 2 ) 2 CH(CH 3 )CH 2 OH + (1− x )C 6 H 14 }, { x (C 2 H 5 ) 2 CHCH 2 OH + (1− x )C 6 H 14 }, and { x C 6 H 12 + (1− x )C 6 H 6 } have been measured for values of x less than about 0.055 by dilution from x ≈ 0.1. Limiting excess partial molar enthalpies H A E, ∞ of the alcohols have been derived.