A boiling-point method for the determination of low vapour pressure

Thomas, Leo H.; Smith, H.K.; Meatyard, R.

doi:10.1088/0022-3735/1/11/314

Cited by 9 publications

(6 citation statements)

References 12 publications

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“…The experimental results are given in Table I, and limits of error involved in the method have been considered previously (10,11). It is considered that the boiling temperatures at their recorded vapor pressures are on average accurate to within ±0.2 °C at vapor pressures above 0.5 torr and to within ±0.3 °C from 0.5 to 0.1 torr.…”

Section: Resultsmentioning

confidence: 99%

“…Vapor Pressure. Vapor pressures are measured by a modified Ramsay and Young method in the manner outlined in previous work (10), keeping the cooling coil at ca. -50 °C by circulation of isopropyl alcohol from a reservoir held at -70 °C.…”

Section: Methodsmentioning

confidence: 99%

“…Reliable determination of vapor pressure below ca. 10 torr is well-known to involve special problems (10) and, with few exceptions (12), published values in this region are inherently prone to systematic error (13). For alcohols, it appears that the only reliable data are those of MCindel (4) for methyl, ethyl, and n-propyl alcohols below 1 torr and possibly those of Drucker et al (2) below 0.4 torr for ethyl alcohol.…”

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confidence: 99%

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Vapor pressures and molar entropies of vaporization of monohydric alcohols

Thomas¹,

Meatyard²,

Smith³

et al. 1979

J. Chem. Eng. Data

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Vapor pressures of nine alcohols In the range 0.04 to about 3 torr have been measured. The results, together with literature data In a higher vapor pressure range, have been fitted to a three-constant (one of which Is universal) equation previously developed In these laboratories for nonassoclated liquids. The equation readily permits evaluation of latent heats of vaporization, and, for n-alcohols, H-bond enthalpies are simply related to the parameters of the equation.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Vapor pressures and molar entropies of vaporization of monohydric alcohols

Thomas¹,

Meatyard²,

Smith³

et al. 1979

J. Chem. Eng. Data

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“…Experimental Method. Numerous techniques have been described for the measurement of vapor pressures. − ,, The ebuliometric method of Ramsay and Young as implemented by Thomas et al was chosen for its suitability and its reliability for measurements at pressures below 1 Pa and at high temperatures. In this method, the liquid refluxes under an inert buffer gas in a glass reflux cell (shown schematically in Figure ), fitted with an electric heater, a condenser, and a thermometer.…”

Section: Vapor Pressures Measurementsmentioning

confidence: 99%

Vapor Pressure and Density of Thermotropic Liquid Crystals: MBBA, 5CB, and Novel Fluorinated Mesogens

2008

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The vapor pressures and densities of six thermotropic liquid crystal-forming molecules (mesogens) have been determined experimentally as functions of temperature. The ubiquitous mesogenic compounds n-(4-methoxybenzylidene)-4-butylaniline (MBBA) and 4'-cyano-4-n-pentylbiphenyl (5CB), which both exhibit room-temperature nematic phases, are examined in this study, as are a number of trifluorinated bicyclohexyl and cyclohexylbiphenyl derivatives which find modern use in display applications. Although thermotropic mesogens are of prime importance in modern optoelectronic technologies, there is a scarcity of reliable saturation pressure data for such systems. An apparatus suitable for measurements of vapor pressures between 0.1 and 1333 Pa in the temperature range 298-523 K has been constructed. The adequacy of the apparatus has been verified by measurements on n-hexadecane at temperatures between 304 and 372 K, corresponding to vapor pressures between 0.4 and approximately 100 Pa. To our knowledge, our measurements represent the first reliable data for the saturation pressure of the fluid phase of these types of thermotropic compounds; we show that existing data for MBBA is thermodynamically inconsistent. The densities of the fluid phases of these compounds are also measured by means of a glass pycnometer at temperatures between 293 and 368 K.

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“…Although convenient, the method as originally described is not a precise one, because the liquid flowing in to replace that evaporated will tend to make the temperature of the thermo meter fall unless the apparatus is elaborated so that the liquid is preheated to the correct temperature. This is most easily achieved if the mode of opera tion is changed from one of intermittent evaporation to one of steady state reflux as in the modification described by Thomas, Smith and Meatyard ( Figure IO) 172 . A glass-fiber skirt, out of which an inverted V is cut to allow free escape of the vapor, is tied round the bulb of a mercury thermometer.…”

Section: Methods Of Ramsay and Youngmentioning

confidence: 99%

Vapor Pressures

Ambrose

1975

Experimental Thermodynamics

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A boiling-point method for the determination of low vapour pressure

Cited by 9 publications

References 12 publications

Vapor pressures and molar entropies of vaporization of monohydric alcohols

Vapor pressures and molar entropies of vaporization of monohydric alcohols

Vapor Pressure and Density of Thermotropic Liquid Crystals: MBBA, 5CB, and Novel Fluorinated Mesogens

Vapor Pressures

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