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.

Studies on kinetics, thermodynamics and sorption characteristics of an inorganic ion exchanger-Titanium phosphate towards PB(II),BI(III) and Th(IV)

Abstract: Amorphous titanium phosphate (TiP), an inorganic ion exchanger of the class of tetravalent metal acid (tma) salts has been synthesized by sol-gel method. TiP has been characterized for elemental analysis (ICP-AES), spectral analysis (FT-IR), thermal analysis (TGA and DSC) and X-ray diffraction studies. Chemical resistivity of the material has been assessed in various media-acids, bases and organic solvents. The Na+ ion exchange capacity (IEC) has been determined and the effect of heating on IEC studied. The sorption/ion exchange behaviour of TiP towards Pb(II), Bi(III) and Th(IV) has been studied at different temperatures (313, 323 and 333 K). Kinetic parameters (overall rate constant k?, equilibrium constant Kc, forward and reverse reaction rate constant k1 and k2, respectively) and thermodynamic parameters (standard free energy ?G0, standard enthalpy ?H0, and standard entropy ?S0) have been evaluated and adsorption (Langmuir and Fruendlich) isotherms have been studied. Based on the above studies, the selectivity order is found to be Pb(II) > Th(IV) > Bi(III) at 333 K.

Synthesis of diethyl carbonate from ethanol through different routes: A thermodynamic and comparative analysis

Abstract: In this study, thermodynamic analysis of various possible synthesis routes of diethyl carbonates (DEC), a benign organic carbonate, was carried out and a comparative analysis was performed. Chemical equilibrium constants at standard conditions were calculated using Gibbs free energy of the system. The Benson group contribution method was used to estimate standard heat of formation and standard entropy change of some raw materials/components like dimethyl carbonate. Variation of heat capacity (Cp) with temperature was estimated for different components from the Rozicka-Domalski model. Variation of chemical equilibrium constants with temperature and pressure was studied for various routes. Synthesis of DEC from ethylene carbonate (EC) was also found to be better considering equilibrium constants at room temperature. The CO2 route was found to be the most unfavourable route for DEC synthesis due to stability of CO2 molecules. Moreover, DEC synthesis through the urea route was found to be best at high temperatures since the equilibrium constants were found to increase exponentially. Experiments were conducted for DEC synthesis using the EC route at two temperatures. Activity coefficients were calculated using the UNIFAC model. Experimentally and theoretically determined chemical equilibrium constant values were found to be similar. PRO/II was also used to minimize Gibbs free energy of the system and estimate the equilibrium constants and the results were comparable with those obtained by the equilibrium constant method and the trend was found to be the same for both the methods.

A method for investigating the effect of temperature on the 695 nm band of insoluble cytochrome c.

Abstract: A method is described for computer analysis of simple spectrophotometric changes in particulate systems, and this has been applied to the bleaching of the 695 nm band of insoluble ferricytochrome c by temperature. The results show that insolubilization has no effect on the standard enthalpy change but lowers the value for the standard entropy change. This effect appears to be independent of the concentration of the gel matrix to which the cytochrome c is bound, but dependent on the ionic strength of the surrounding solution.