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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: In this paper, the relative stability of polychlorinated pyrenes (PCPY) is investigated using density functional theory (DFT) at the B3LYP/6-311G(d,p) level and their thermodynamic properties in the ideal gas state, such as standard heat capacity at constant volume, standard entropy, standard enthalpy of formation, and standard Gibbs free energy of formation (ΔfG∘), were computed.

2 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the activity of zinc in liquid Cd-Zn-Ga alloys by electrochemical technique based on molten salt electrolyte galvanic cell in the temperature range 723 to 823 K along three pseudo-binary lines of Zn-(Cd ≥ 0.75, 0.50, and 0.25).
Abstract: Activity of zinc in liquid Cd-Zn-Ga alloys has been measured by electrochemical technique based on molten salt electrolyte galvanic cell in the temperature range 723 to 823 K along three pseudo-binary lines of Zn-(Cd y Ga1−y ), where y = 0.75, 0.50, and 0.25. The excess molar free energy, enthalpy, and entropy were computed by the Darken’s treatment of the ternary solutions using published data of the relevant binary solutions and the ternary system investigated. The excess molar free energy surface of the ternary confirms substantially what one would expect from the knowledge of the corresponding curves of the component binary systems. The excess molar free energy surfaces have the maxima in the Cd-Ga side. The extremum value of molar excess free energy was found to be 3.24 kJ/mol (x Cd = 0.5, x Zn = 0.125, and x Ga = 0.375) at 800 K. The excess molar enthalpy curves have been found to be tilted toward the Zn-Cd and Cd-Ga sides. The extremum value of excess molar enthalpy was found to be 2.58 kJ/mol (x Ga = 0.3 and x Zn = x Cd = 0.35) at 800 K. The excess molar entropy surfaces have the maxima in the Zn-Ga side and minima in the Cd-Ga side. The slope-intercept method was used to compute the partial molar quantities. The activities are computed from the partial molar excess free energy for three components at 800 K. The isoactivity surfaces of the three components are depicted by the isoactivity lines. The activities of all three components show positive deviation from the Raoult’s law. The excess molar free energies of the Cd-Zn-Ga system obtained experimentally are compared with those estimated from the theoretical models.

2 citations

Journal ArticleDOI
Lei Zhang1, Yingnan Wang1, Zhu Yuan1, Z. Y. Zhao1, Xingjia Guo1, H. C. Chang1 
TL;DR: In this article, a new method using nano-TiO2 as solid-phase extractant has been developed for the determination of trace amount of indium element, where the adsorption rate of In3+ was more than 95% at pH 3.0–5.0.
Abstract: A new method using nano-TiO2 as solid-phase extractant has been developed for the determination of trace amount of indium element. The adsorption pH curves, adsorption isotherms and adsorption capacities were obtained. It was found that the adsorption rate of In3+ was more than 95% at pH 3.0–5.0. The adsorption reaches equilibrium in a short time, and follows the Langmuir isotherm. From the results of the thermodynamic analysis, the adsorption constant KC, standard free energy G0, standard enthalpy H0, and standard entropy S0 of the adsorption process were calculated. The standard thermodynamic function changes were G0 0, and S0 > 0 respectively, which indicated that the adsorption was a spontaneous increasing enthalpy and entropy driving process. The positive value of S0 for adsorption could be explained by the release of the attached water molecules from In3+ into solution as In3+ adsorbed on substrate and contributed to the increase in the degree of freedom at the solid-solution interface during the adsorption process. Flourier Transformation Infrared Spectrum and X-ray Diffraction investigated the structure of nano-TiO2. The results and the thermodynamic data indicated that In3+ adsorption onto nano-TiO2was characterized by physical adsorption.

2 citations

Journal ArticleDOI
TL;DR: In this article, the standard enthalpies and entropies of hydrogen, carbon, chlorine, and bromine atoms, when interacting dispersively with n-octadecane, are calculated from retention measurements made on some substituted methanes.
Abstract: The standard enthalpies and entropies of hydrogen, carbon, chlorine, and bromine atoms, when interacting dispersively with n-octadecane, are calculated from retention measurements made on some substituted methanes. A clean linear correlation between the standard enthalpy and standard entropy of interaction is demonstrated and it is also shown that there is a linear relationship between the standard free enthalpy of interaction of the elements investigated and their atomic polarizability. The results also indicate that there is another factor, independent of the element polarizability that contributes to the standard enthalpy of interaction. It is postulated that this factor may be a function of some property of the stationary phase.

2 citations

Journal Article
TL;DR: In this paper, the heat capacity of tripropylarsine was measured in an adiabatic vacuum calorimeter in the temperature range 6-300 K and the vitrification and melting temperatures were determined.
Abstract: The heat capacity of tripropylarsine was measured in an adiabatic vacuum calorimeter in the temperature range 6-300 K. The vitrification and melting temperatures were determined and the thermodynamic functions of tripropylarsine were calculated for the vitreous, crystalline, and liquid states in the temperature range of measurements. The standard entropy of formation of As(n-C 3 H 7 ) 3 at 298.15 K was calculated. The zero entropy of the substance in the vitreous state and the difference of its zero enthalpies in the crystalline and vitreous states were estimated.

2 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202229
202141
202055
201949
201857