The torsion method and a coupled torsion—Knudsen effusion apparatus were used to measure the vapo... more The torsion method and a coupled torsion—Knudsen effusion apparatus were used to measure the vapour pressures of o, m and p-chlorobiphenyls. The equations selected were: o-chlorobiphenyl(l), log P(kPa) = (10.48±0.50)-(4149±230)/T; m-chlorobiphenyl(l), log P(kPa) = (8.68±0.47)-(3614±188)/T; p-chlorobiphenyl(s), log P(kPa) = (9.44±0.63)-(3849 ± 200)/T; and p-chlorobiphenyl(l), log P(kPa) = (8.28±0.55)-(3541±250)/T. The free energy functions, (GoT-Ho298)/T, for gaseous o and p-chlorobiphenyls were also estimated.
The sublimation enthalpies of monophenylurea (MPhU) and diphenyl-1,3 urea (1,3-DPhU) have been de... more The sublimation enthalpies of monophenylurea (MPhU) and diphenyl-1,3 urea (1,3-DPhU) have been derived from the dependence of their vapour pressures on temperature, as measured by the torsion-effusion method. Values obtained are: 136 kj mol−1 for MPhU and 152 kJ mol−1 for 1,3-DPhU, where the estimated errors are comprised within 6 kJ mol−1Enthalpies and temperatures of fusion have been measured by differential scanning calorimetry, leading to 23.7 kJ mol−1 and 420.6 K for MPhU, and 34.6 kJ mol−1 and 512 K for 1,3-DPhU. Poor reproducibility of results for 1,3-DPhU seems be due to the beginning of decomposition. No solid-to-solid transitions have been revealed from r.t. to fusion for both compounds.
The iron-tellurium system presents a single-phase region, β phase, with boundaries at composition... more The iron-tellurium system presents a single-phase region, β phase, with boundaries at compositions near to the stoichiometric one, FeTe, and to the formula FeTe0.85. By the torsion-effusion method the total vapour pressure of the β phase at these two boundary compositions was measured. The pressure-temperature equations log p(kPa) = (8.37±0.45)−(9353±376)/T and log p(kPa)=(7.76±0.10)−(10229±109)/T, associated respectively with the vaporization processes 33.3 FeTe(s)→ 33.3 FeTe0.94(s)+Te2(g) and 2.35 FeTe0.85(s) → 2.35 α-Fe(s) + Te2(g), were derived. The enthalpies associated with these reactions are ΔHstuggeredT0=180.3 ± 10 kJ mol−1 derived from the only second-law treatment of the data for the first reaction, and ΔHstuggered2980= 209.5 ± 2.0 kJ mol−1 for the second reaction as the average of the second- and third-law development of the partial pressure of Te2. From the last reaction, the heat of formation of FeTe0.85ΔformHstuggered2980=17.5±2.0 kJ mol−1 was derived.
Sublimation enthalpies of eleven alkyl dervatives of urea (monomethylurea, monoethyl-urea, monopr... more Sublimation enthalpies of eleven alkyl dervatives of urea (monomethylurea, monoethyl-urea, monopropylurea, monoisopropylurea, monoisobutylurea, mono-t-butylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,3-diethylurea, 1,3-dibutylurea and 1,1,3-trimethylurea) were determined from second-law treatment of vapour pressures measured by the torsion-effusion method and compared with earlier results.
The vaporization of solid AlAs was studied using the mass spectrometry and Knudsen effusion techn... more The vaporization of solid AlAs was studied using the mass spectrometry and Knudsen effusion techniques. This compound vaporizes according to the reaction The pressure of As2(g) depends on the temperature according to the equation where P is in kilopascals. A value of ΔH298° = 163 ± 7 kJ mol−1 associated with the vaporization reaction was derived by second-law treatment of the pressure data. The free-energy function and the standard heat of formation (ΔHform° = 62 ± 7 kJ mol−1) of AlAs(s) were also calculated.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Vapor pressures of solid antimony tribromide were measured by the torsion—effusion technique. The... more Vapor pressures of solid antimony tribromide were measured by the torsion—effusion technique. The values obtained can be expressed by the equation log P(atm) = (9.3 ± 1.3) − (4.4 ± 0.5)/T in the temperature range 324–368 K.The standard heat of vaporization was derived by second- and third-law treatment of the data and compared with values reported in the literature. The value ΔH0vap (298 K) = 19.5 ± 0.5 kcal mole−1 was derived.
The temperature dependence of vapour pressures for liquid C7 to C15 odd-numbered terminal diols w... more The temperature dependence of vapour pressures for liquid C7 to C15 odd-numbered terminal diols was measured by the torsion-effusion method. Corresponding vaporization enthalpies were derived.
A preliminary investigation on the feasibility of laser deposition of FeV alloy films on mild st... more A preliminary investigation on the feasibility of laser deposition of FeV alloy films on mild steel has been carried out starting from a commercial FeV (48 at.% Fe) target. The morphological and microchemical analysis performed by the SEM-EDS technique revealed a layered growth mechanism with retention of the stoichiometry. The deposited films present appropriate characteristics and an appreciable adherence with localised stress phenomena.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The enthalpy and entropy of sublimation of N-ethylthiourea were obtained from the temperature dep... more The enthalpy and entropy of sublimation of N-ethylthiourea were obtained from the temperature dependence of its vapour pressure measured by both the torsion–effusion and the Knudsen effusion method in the temperature range 360–380 K. The compound undergoes no solid-to-solid phase transition or decomposition below 380 K. The pressure against reciprocal temperature resulted in lg(p, kPa) = (13.40 ± 0.27) − (6067 ± 102) /T(K). The molar sublimation enthalpy and entropy at the mid interval temperature were ΔsubHm(370 K) = (116.1 ± 2.0) kJ mol−1 and ΔsubSm(370 K) = (218.0 ± 5.2) J mol−1 K−1, respectively. The same quantities derived at 298.15 K were (118.8 ± 2.1) kJ mol−1 and (226.1 ± 5.5) J mol−1 K−1, respectively.
The activity of magnesium in liquid InMg alloys at 900 K has been determined by measuring its va... more The activity of magnesium in liquid InMg alloys at 900 K has been determined by measuring its vapour pressure with a torsion-effusion apparatus. The results indicate a large negative deviation from ideality. Partial molar thermodynamic properties of magnesium have been derived.
The torsion method and a coupled torsion—Knudsen effusion apparatus were used to measure the vapo... more The torsion method and a coupled torsion—Knudsen effusion apparatus were used to measure the vapour pressures of o, m and p-chlorobiphenyls. The equations selected were: o-chlorobiphenyl(l), log P(kPa) = (10.48±0.50)-(4149±230)/T; m-chlorobiphenyl(l), log P(kPa) = (8.68±0.47)-(3614±188)/T; p-chlorobiphenyl(s), log P(kPa) = (9.44±0.63)-(3849 ± 200)/T; and p-chlorobiphenyl(l), log P(kPa) = (8.28±0.55)-(3541±250)/T. The free energy functions, (GoT-Ho298)/T, for gaseous o and p-chlorobiphenyls were also estimated.
The sublimation enthalpies of monophenylurea (MPhU) and diphenyl-1,3 urea (1,3-DPhU) have been de... more The sublimation enthalpies of monophenylurea (MPhU) and diphenyl-1,3 urea (1,3-DPhU) have been derived from the dependence of their vapour pressures on temperature, as measured by the torsion-effusion method. Values obtained are: 136 kj mol−1 for MPhU and 152 kJ mol−1 for 1,3-DPhU, where the estimated errors are comprised within 6 kJ mol−1Enthalpies and temperatures of fusion have been measured by differential scanning calorimetry, leading to 23.7 kJ mol−1 and 420.6 K for MPhU, and 34.6 kJ mol−1 and 512 K for 1,3-DPhU. Poor reproducibility of results for 1,3-DPhU seems be due to the beginning of decomposition. No solid-to-solid transitions have been revealed from r.t. to fusion for both compounds.
The iron-tellurium system presents a single-phase region, β phase, with boundaries at composition... more The iron-tellurium system presents a single-phase region, β phase, with boundaries at compositions near to the stoichiometric one, FeTe, and to the formula FeTe0.85. By the torsion-effusion method the total vapour pressure of the β phase at these two boundary compositions was measured. The pressure-temperature equations log p(kPa) = (8.37±0.45)−(9353±376)/T and log p(kPa)=(7.76±0.10)−(10229±109)/T, associated respectively with the vaporization processes 33.3 FeTe(s)→ 33.3 FeTe0.94(s)+Te2(g) and 2.35 FeTe0.85(s) → 2.35 α-Fe(s) + Te2(g), were derived. The enthalpies associated with these reactions are ΔHstuggeredT0=180.3 ± 10 kJ mol−1 derived from the only second-law treatment of the data for the first reaction, and ΔHstuggered2980= 209.5 ± 2.0 kJ mol−1 for the second reaction as the average of the second- and third-law development of the partial pressure of Te2. From the last reaction, the heat of formation of FeTe0.85ΔformHstuggered2980=17.5±2.0 kJ mol−1 was derived.
Sublimation enthalpies of eleven alkyl dervatives of urea (monomethylurea, monoethyl-urea, monopr... more Sublimation enthalpies of eleven alkyl dervatives of urea (monomethylurea, monoethyl-urea, monopropylurea, monoisopropylurea, monoisobutylurea, mono-t-butylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,3-diethylurea, 1,3-dibutylurea and 1,1,3-trimethylurea) were determined from second-law treatment of vapour pressures measured by the torsion-effusion method and compared with earlier results.
The vaporization of solid AlAs was studied using the mass spectrometry and Knudsen effusion techn... more The vaporization of solid AlAs was studied using the mass spectrometry and Knudsen effusion techniques. This compound vaporizes according to the reaction The pressure of As2(g) depends on the temperature according to the equation where P is in kilopascals. A value of ΔH298° = 163 ± 7 kJ mol−1 associated with the vaporization reaction was derived by second-law treatment of the pressure data. The free-energy function and the standard heat of formation (ΔHform° = 62 ± 7 kJ mol−1) of AlAs(s) were also calculated.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Vapor pressures of solid antimony tribromide were measured by the torsion—effusion technique. The... more Vapor pressures of solid antimony tribromide were measured by the torsion—effusion technique. The values obtained can be expressed by the equation log P(atm) = (9.3 ± 1.3) − (4.4 ± 0.5)/T in the temperature range 324–368 K.The standard heat of vaporization was derived by second- and third-law treatment of the data and compared with values reported in the literature. The value ΔH0vap (298 K) = 19.5 ± 0.5 kcal mole−1 was derived.
The temperature dependence of vapour pressures for liquid C7 to C15 odd-numbered terminal diols w... more The temperature dependence of vapour pressures for liquid C7 to C15 odd-numbered terminal diols was measured by the torsion-effusion method. Corresponding vaporization enthalpies were derived.
A preliminary investigation on the feasibility of laser deposition of FeV alloy films on mild st... more A preliminary investigation on the feasibility of laser deposition of FeV alloy films on mild steel has been carried out starting from a commercial FeV (48 at.% Fe) target. The morphological and microchemical analysis performed by the SEM-EDS technique revealed a layered growth mechanism with retention of the stoichiometry. The deposited films present appropriate characteristics and an appreciable adherence with localised stress phenomena.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The enthalpy and entropy of sublimation of N-ethylthiourea were obtained from the temperature dep... more The enthalpy and entropy of sublimation of N-ethylthiourea were obtained from the temperature dependence of its vapour pressure measured by both the torsion–effusion and the Knudsen effusion method in the temperature range 360–380 K. The compound undergoes no solid-to-solid phase transition or decomposition below 380 K. The pressure against reciprocal temperature resulted in lg(p, kPa) = (13.40 ± 0.27) − (6067 ± 102) /T(K). The molar sublimation enthalpy and entropy at the mid interval temperature were ΔsubHm(370 K) = (116.1 ± 2.0) kJ mol−1 and ΔsubSm(370 K) = (218.0 ± 5.2) J mol−1 K−1, respectively. The same quantities derived at 298.15 K were (118.8 ± 2.1) kJ mol−1 and (226.1 ± 5.5) J mol−1 K−1, respectively.
The activity of magnesium in liquid InMg alloys at 900 K has been determined by measuring its va... more The activity of magnesium in liquid InMg alloys at 900 K has been determined by measuring its vapour pressure with a torsion-effusion apparatus. The results indicate a large negative deviation from ideality. Partial molar thermodynamic properties of magnesium have been derived.
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