Design, Construction, and Testing of a Heat of Vaporization Calorimeter useful in the Vapor Pressure Range 1 to 0.01 mm Hg at 25 degrees C.

Morawetz, Ernst; Sunner, Stig; Wiberg, Örjan

doi:10.3891/acta.chem.scand.17-0473

Cited by 19 publications

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“…The effects of the following variations in the experimental techniques were investigated: (a) size of sample, 1 mg, 2 mg, 4 mg,10 mg, 20 mg; (b) material of bucket holding sample, quartz or PTFE; (c) height of bucket, 5 mm or 10 mm; (d) i.d. of bucket, 2 mm, 3 mm, 4 mm; (e) with or without liquid nitrogen around glass envelope around heater.…”

mentioning

confidence: 99%

Rates of molecular vaporization of linear alkanes

Wall¹,

Flynn²,

Straus³

1970

J. Phys. Chem.

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mentioning

confidence: 99%

Rates of molecular vaporization of linear alkanes

Wall¹,

Flynn²,

Straus³

1970

J. Phys. Chem.

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“…In the first group, the sublimation enthalpy is determined directly at a fixed temperature. Among this group are, for example, the vacuum sublimation drop-microcalorimetry − and Calvet microcalorimetry. − The indirect group includes techniques in which the temperature dependence of the vapor pressure (or some other parameter proportional to it) is measured, and here the Clausius–Clapeyron equation is used. The effusion method is the most commonly used indirect method. − …”

Section: Introductionmentioning

confidence: 99%

Isothermal Thermogravimetric Study for Determining Sublimation Enthalpies of Some Hydroxyflavones

et al. 2018

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The sublimation enthalpies of some hydroxyflavones and one amineflavone were determined with a thermogravimetric device under isothermal conditions. These enthalpies were obtained by measuring the rate of mass loss as a function of temperature. In this methodology, the Clausius−Clapeyron and Langmuir equations were used. The diffusional effect of the gas phase was included in the Langmuir equation. In order to test and validate the experimental methodology, the sublimation enthalpy of three standard materials, anthracene, pyrene, and benzoic acid, were determined. The values obtained are in agreement with the data reported and recommended in the literature. Low uncertainties were obtained in all thermogravimetric measurements. Additionally, by differential scanning calorimetry, the molar fraction, temperature and enthalpy of fusion, and heat capacity of the solid phase were determined for all of the compounds studied. The heat capacities of the gas phase were estimated using computational methods. Isothermal thermogravimetry was applied to study a family of flavones.

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Direct determination of enthalpies of vaporization of liquid compounds by a miniaturized effusion cell adapted to a commercial microcalorimeter

Barone

Gatta

Elia

1984

Journal of Thermal Analysis

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A miniaturized effusion cell adapted to a Sorpt~on LKB microcatorimeter has been designed, built and tested. Vaporization is performed isothermally into a vacuum through a small orifice permitting a vapour pressure very close to the equilibrium values. The cell has been tested by measuring the enthalpies of vaporization at 298.15 K of reference liquid compounds (water, benzene, propanol-1, propanol-2) with a reproducibility better than 1%. Enthalpies of vaporization of butanol-1 and deuterated water have also been determined.Accurate knowledge of the enthalpies of vaporization of both liquid and solid compounds is of greatest importance in a wide spectrum of thermodynamic calculations, from enthalpies of formation [1] to enthalpies of solvation [2]. This accuracy is the more indispensable the weaker the interactions concerned are. In particular, AvapH values are employed to obtain enthalpies of solvation from solution heats at infinite dilution, allowing a closer description of the solute-solvent interactions [3, 4], as well as the possible partition of different contributions (e.g. solvent restructuring effect and hydrophobic interactions).The additive character of the vaporization enthalpies has been proved but the correlations so far established [5][6][7][8] are restricted to liquid compounds of relatively small dimensions and simple molecular structure (e.g. with linear chain substituents). Direct and very precise determinations of vaporization enthalpies are thus increasingly required, particularly in connection with the more widespread employment of highsensitivity microcalorimeters.Several experimental techniques for the calorimetric determination of vaporization enthalpies for both liquid and solid compounds have been developed in the last twenty years |9-16], Part are based on the measurement of the heat required to vaporize a well-known amount of substance into a vacuum under defined conditions as close as possible to the equilibrium values. These direct methods have proved useful, but their 9

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Design, Construction, and Testing of a Heat of Vaporization Calorimeter useful in the Vapor Pressure Range 1 to 0.01 mm Hg at 25 degrees C.

Cited by 19 publications

References 0 publications

Rates of molecular vaporization of linear alkanes

Rates of molecular vaporization of linear alkanes

Isothermal Thermogravimetric Study for Determining Sublimation Enthalpies of Some Hydroxyflavones

Direct determination of enthalpies of vaporization of liquid compounds by a miniaturized effusion cell adapted to a commercial microcalorimeter

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