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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: This paper reviews the recent methodological advances of the use of ACE in studying the complex equilibria of radionuclides in aqueous solutions and special attention is paid to a number of species involved in equilibrium.
Abstract: Interaction of radionuclides with inorganic and organic species present in natural environment plays an important role in their eventual dispersion. The complex equilibria established in the aqueous phase cause significant changes in the migration properties of radionuclides. Affinity capillary electrophoresis (ACE) can be fruitful in studying these equilibria. This paper reviews the recent methodological advances of the use of ACE in studying the complex equilibria of radionuclides in aqueous solutions. Special attention is paid to the determination of a number of species involved in equilibrium, species constituents (number of ligands, protonated, deprotonated), the influence of ionic strength and temperature on stability constants of complex species formed. Use of ACE for the determination of the main thermodynamic parameters (the molar Gibbs energy (Δr Gm ), the molar enthalpy (Δr Hm ) and the molar entropy (Δr Sm )) of complex formation reactions is also discussed. These data are essential to predict dispersion of radionuclides in the natural environment.
17 citations
TL;DR: The equilibrium constants of the liquid-phase dehydration of 1-hexanol to dihexyl ether (DNHE) and water were determined in the temperature range of (423 to 463) K on Amberlyst 70 as mentioned in this paper.
Abstract: The equilibrium constants of the liquid-phase dehydration of 1-hexanol to dihexyl ether (DNHE) and water were determined in the temperature range of (423 to 463) K on Amberlyst 70. The equilibrium constants of the two main side reactions, DNHE decomposition to 1-hexene and 1-hexanol and isomerization of 1-hexene to 2-hexene, were also studied. The etherification reaction proved to be slightly exothermic, with an enthalpy change of reaction of −(9.5 ± 0.2) kJ·mol−1 at 298 K. From this value, the standard formation enthalpy and molar entropy of DNHE were computed to be −(478.6 ± 0.8) kJ·mol−1 and (517.4 ± 0.5) J·K−1·mol−1, respectively. A correction concerning the effect of pressure on the entropy proved to be necessary when computing liquid-phase entropy from gas-phase data. The isomerization of 1-hexene to 2-hexene is exothermic, whereas the decomposition of DNHE is endothermic.
17 citations
TL;DR: In this article, the standard entropy of formation at 298 K, Δ f S 298, was determined from measuring the heat capacities, Cp, from near absolute zero (2 K) to 300 K by the relaxation method.
Abstract: The thermodynamic properties of Zn 8 La were investigated by calorimetry. The standard entropy of formation at 298 K, Δ f S 298 , was determined from measuring the heat capacities, Cp, from near absolute zero (2 K) to 300 K by the relaxation method. The standard enthalpy of formation at 298 K, Δ f H 298 , was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation at 298 K, Δ f G 298 , was determined from these data. The results obtained were as follows: Δ f H 298 (Zn8La)/kJ·mol -1 =-297.18 ±18; Δ f S 298 (Zn 8 La)/J·mol -1 ·K -1 = -25.02±3.60; Δ f G 298 (Zn 8 La)/kJ·mol -1 =-289.71 ± 18. The coefficient, γ, of the electronic term contributing to the heat capacity of Zn 8 La was small, indicating that decrease of the density of states for 4f component of the lanthanum atom in the vicinity of E F .
17 citations
TL;DR: In this article, the crystal structure and composition of (C12H25NH3)(2)ZnCl4(s) were characterized by chemical and elemental analysis and the lattice energy of the title compound was calculated to be U-POT=888.82 kJ.
Abstract: The crystal structure and composition of (C12H25NH3)(2)ZnCl4(s) were characterized by chemical and elemental analysis. X-ray powder diffraction technique and X-ray crystallography. The lattice energy of the title compound was calculated to be U-POT=888.82 kJ.mol(-1). Low temperature heat capacities of the title compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 403 K. An obvious solid to solid phase transition occurred in the heat capacity curve, and the peak temperature, molar enthalpy and molar entropy of the phase transition of the compound were determined to be T-trs=(364.02 +/- 0.03) K, Delta H-trs(m) = (77.567 +/- 0.341) kJ.mol(-1), and Delta S-trs(m)=(213.77 +/- 1.17) J.K-1.mol(-1), respectively. Experimental molar heat capacities before and after the phase transition were respectively fitted to two polynomial equations. The smoothed molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at an interval of 5 K.
17 citations
TL;DR: The real standard entropy of ions in water is calculated from the temperature coefficient of the outer potential difference between a solution and the metal phase of an electrode reversible to one of the ions in the solution as mentioned in this paper.
Abstract: The real standard entropy of ions in water is calculated from the temperature coefficient of the outer potential difference between a solution and the metal phase of an electrode reversible to one of the ions in the solution. Sone related real single-ion thermodynamic properties are derived; the value of the temperatures coefficient of the surface potential of water has been evaluated to within ±40 µV K–1.
17 citations