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Standard molar entropy
About: Standard molar entropy is a research topic. Over the lifetime, 1586 publications have been published within this topic receiving 29886 citations.
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TL;DR: The vapor pressures of aqueous solutions of 1-ethyl-3-methylimidazolium-based ionic liquids (IL) with counteranions, tetrafluoroborate, trifluoromethanesulfonate, and iodide are determined to indicate that the affinity of each IL is ranked in the descending order.
Abstract: We determined the vapor pressures of aqueous solutions of 1-ethyl-3-methylimidazolium ([C 2mim])-based ionic liquids (IL) with counteranions, tetrafluoroborate (BF 4 (-)), trifluoromethanesulfonate (OTF (-)), and iodide (I (-)). Because in literature the evidence is accumulating and pointing to the fact that ionic liquid ions do not dissociate in aqueous media for the most of the concentration range, we analyzed the vapor pressure data on the basis of binary mixture, and the excess chemical potentials of each component were calculated. From these, the intermolecular interactions in terms of excess chemical potential and hence the concentration fluctuations were evaluated. Though any further discussion into the mixing schemes of the mixture awaits the excess partial molar enthalpy and hence the excess partial molar entropy data, the net interaction in terms of excess chemical potential indicates that the affinity of each IL is ranked in the descending order [C 2mim]I > [C 2mim]OTF > [C 2mim]BF 4. This is consistent with our earlier findings that [C 2mim] (+) is modestly amphiphilic with almost equal hydrophobicity and hydrophilicity, I (-) is a hydrophile, and OTF (-) is amphiphilic, and BF 4 (-) is believed to be strongly hydrophobic.
15 citations
TL;DR: In this article, the Clausius-Clapeyron equation was used to derive the standard molar enthalpies of combustion, in oxygen, at the temperatureT= 298.15 K, measured by static bomb-combustion calorimetry; the Knudsen mass-loss effusion technique was then used to measure the vapour pressures of the crystals as functions of temperature.
14 citations
TL;DR: In this paper, the standard molar ideal gas thermodynamic functions of the singly and doubly charged uranyl, neptunyl, plutonyl and americyl ions MOn+2(n= 1 or 2) have been calculated from structural, and electronic and vibrational spectroscopic data.
Abstract: The standard molar ideal gas thermodynamic functions of the singly and doubly charged uranyl, neptunyl, plutonyl and americyl ions MOn+2(n= 1 or 2) have been calculated from structural, and electronic and vibrational spectroscopic data. Estimates have been made for values not found in the literature. The heat capacity, entropy, enthalpy and Gibbs free energy are reported over the temperature range 100–1000 K. The values for 298.15 K have been combined with the standard partial molar entropies of these ions in aqueous solutions to yield the standard molar entropies of hydration. For the hexavalent uranyl ion data are also available for the standard partial molar heat capacity of the aqueous ion and the standard molar heat of formation of the gaseous ion, so that the corresponding quantities of hydration could be calculated. The thermodynamic functions of hydration are interpreted in terms of a model for the hydrated ions.
14 citations
01 Aug 2001-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the Gibbs energy of formation of NaCl and NaAlCl4 has been measured in the temperature range from 423 to 623 K by a novel galvanic cell technique involving in-situ electrogenerated chlorine electrode.
Abstract: The phase relations in the NaCl-AlCl3 system (
$$0.3 \leqslant N_{AlCl_3 } \leqslant 0.65$$
) have been determined in the temperature range from 373 to 623 K by isothermal equilibration, electrical conductivity, and electromotive force measurements. Only one ternary compound, NaAlCl4, was found to be stable, with a melting point of 426 K. The standard Gibbs energy of formation of NaCl and NaAlCl4 has been measured in the temperature range from 423 to 623 K by a novel galvanic cell technique involving in-situ electrogenerated chlorine electrode in the Na/β″-alumina/NaCl, NaAlCl4/Cl2,C and Al/NaCl, NaAlCl4/Cl2,C cells along with the Na/β″-alumina/NaCl,NaAlCl4/Al cell. The Δ
f
G
NaCl(
)/o
and
$$\Delta _f G_{NaAlCl_4 (l)}^ \circ $$
values have been calculated as −412.4+0.095 T (±1) kJ mol−1 and −1117.5+0.2460 T (±2) kJ mol−1, respectively. The standard entropy of NaAlCl4 (s) at 298 K, computed from the results of the study and the auxiliary information from the literature (184 J K−1 mol−1), show good agreement with the estimated JANAF value (188.28 J K−1 mol−1). The enthalpy of formation of NaAlCl4 (l) from NaCl (s) and AlCl3 (s) at 550 K obtained in the present study (−1850 J mol−1) is in agreement with that computed from the heat-capacity measurements (−1910 J mol−1). The present measurements are unique, as a new electrochemical technique is employed in a cell with low-melting sodium chloroaluminate electrolyte to obtain the thermodynamic properties of NaCl and NaAlCl4 at significantly low temperatures. The Gibbs energy of formation of NaCl (s) is, thus, measured at temperatures as low as 423 K by an electrochemical technique for the first time, in this work.
14 citations
TL;DR: In this article, the lattice parameter and O/M ratio of the solid solution, CayU1−yO2+x, prepared in a stream of helium were investigated, and the single phase region of the cubic fluorite type solid solution extended from 0.03 to 0.33.
14 citations