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.

Phase Equilibria in the Cu 2 Se–Cu 3 AsSe 4 –Se System and Thermodynamic Properties of Cu 3 AsSe 4

Abstract: The Cu2Se–Cu3AsSe4–Se system has been studied using differential thermal analysis, X-ray diffraction, and emf measurements on concentration cells using Cu4RbCl3I2 as a solid electrolyte. We have constructed a number of vertical sections through the phase diagram, the room-temperature solid-state phase compatibility diagram, and a projection of the liquidus surface. The primary crystallization fields of the phases present and the types and coordinates of in- and univariant equilibria in the system have been identified. The system has been shown to contain a broad liquid–liquid immiscibility region. Using emf data, we evaluated the standard thermodynamic functions of formation and standard entropy of the Cu3AsSe4 compound.

Calorimetric Study of Natural Anapaite

Abstract: The thermochemical study of natural hydrous calcium and iron phosphate, anapaite Ca2Fe(PO4)2 · 4H2O (Kerch iron ore deposit, Crimea, Russia), was carried out using high-temperature melt solution calorimetry with a Tian-Kalvet microcalorimeter. The enthalpy of formation of the mineral from elements was obtained to be Δ f Hel°(298.15 K) =–4812 ± 16 kJ/mol. The values of the standard entropy and the Gibbs energy of anapaite formation are S°(298.15 K) = 404.2 J/K mol and Δ f Gel°(298.15 K) =–4352 ± 16 kJ/mol, respectively.

Thermodynamic Properties of Ph 4 Sb(OC(O)C≡CPh)

Abstract: The temperature dependence of the specific heat capacity of tetraphenylantimony phenylpropiolate Ph4Sb(OC(O)C≡CPh) in the range of 6–450 K is studied via adiabatic vacuum and differential scanning calorimetry for the first time. The studied compound is found to melt with decomposition. The standard thermodynamic functions $$C_{p}^{ \circ }$$(T), $$H^\circ (T) - H^\circ (0)$$, $$S^\circ (T)$$, and $$G^\circ (T) - H^\circ (0)$$ are calculated for the crystalline Ph4Sb(OC(O)C≡CPh) in the range of Т → 0 to 450 K using the obtained experimental data. Multifractal processing of the low-temperature (T< 50 K) heat capacity of the studied compound is performed, and the chain–sheet topology of its structure is determined. The energy of combustion of crystalline Ph4Sb(OC(O)C≡CPh) at T = 298.15 K is measured with a static bomb inside a combustion calorimeter. The standard enthalpy of combustion, the standard enthalpy of formation ∆fH°, the standard entropy of formation ∆fS°, and the standard Gibbs energy of formation ∆fG° of the substance in the crystalline state at T = 298.15 K are calculated from the obtained experimental data.

Physicochemical Properties of the Protic Ionic Liquid Bis(2-hydroxyethyl)methylammonium Formate

Abstract: A protic ionic liquid, bis(2-hydroxyethyl)methylammonium formate, (BHEMF), was synthesized and characterized. The density and surface tension of the protic ionic liquid were determined in the temperature range of 293.15–343.15 K. The molar volume and surface entropy were estimated from the experimental density and surface tension data, respectively. In terms of Glasser’s theory, the standard molar entropy and lattice energy of the protic ionic liquid were estimated. Using the methods of Kabo and Rebelo, the molar enthalpy vaporization of the protic ionic liquid, $$ ^{l} \Updelta^{g}H_{\text{m}}^{0} $$ (298.15 K) at 298.15 K and $$ ^{l} \Updelta^{g}H_{\text{m}}^{0} $$ (T b), at the hypothetical normal boiling point were estimated, respectively. According to the interstical model, the thermal expansion coefficient of the protic ionic liquid, α, was calculated and the result is in very good agreement with the experimental value.