Authors:J. Tareen, A. Fazeli, B. Basavalingu, and G. Bhandige
Decarbonation curve for the synthetic dolomite analogues; (Cd-dolomites) were determined for CdMg(CO3)2, CdMn(CO3)2 and CdZn(CO3)2 under CO2 pressure of up to 2.5 kbar. All the three double carbonates were completely disordered at the decomposition temperatures
and hence the thermodynamic data (Standard enthalpy; ΔHfo, Standard free energy; ΔGfo) retrieved from the univariant decarbonation curve corresponds to the disordered phases. They are:
The mixing enthalpies and free energies for the formation of the disordered 1∶1 solid solution phases are:
The thermodynamic data (ΔHfo, ΔGfo and ΔHro, ΔGro) showed a positive correlation with the decomposition temperatures. The mixing energies of the disordered double carbonates
also show a direct correlation with the cationic size differences.
Authors:V. I. Pet’kov, E. A. Asabina, A. V. Markin, N. N. Smirnova, and D. B. Kitaev
Summary The thermodynamic data for NZP compounds MZr2(PO4)3 (M=Na, K, Rb, Cs, Zr0.25) and Na5D(PO4)3 (D=Ti, Zr) are reported. The heat capacities of the phosphates were measured between T=7 and T=640 K. The standard enthalpies entropies, and Gibbs functions of formation at T=298.15 K were derived. The obtained thermodynamic characteristics of phosphates of the NZP type structure and literature data are summarized. Thermodynamic functions of reactions of solid-state synthesis were calculated and the usability of ceramic technology for obtaining NZP compounds was proved.
The temperature-dependence of the specific heat near to the glass temperature was investigated for several Te- and As-based chalcogenide glasses, the latent heats of melting and crystallization of the former alloys also being measured. No thermal change could be detected in the transformation of the As-based alloys from the solid to the liquid state.
Authors:B. Sarangi, H. Ray, K. Tripathy, and A. Sarangi
Differential thermal analysis has been used for quantitative determination of heats of aluminothermic redox reaction of MnO2 and V2O5 over a wide range of temperatures. Heat of reaction V2O5−Al and MnO2−Al systems have been determined using the calibration plot established. The experimentally determined values compare well
with those predicted from thermodynamic data available in the literature. It has been found that V2O5−Al system involves a higher heat of reaction in comparison to the MnO2−Al system.
Authors:V. Pet’kov, E. Asabina, A. Markin, and N. Smirnova
Data on synthesis, thermal behavior and thermodynamic properties for the NZP phosphates NaMe2(PO4)3 and Na5Me(PO4)3 (Me=Ti, Zr, Hf) are reported. The compounds were synthesized by sol-gel method and solid-state reactions and characterized by
X-ray powder diffraction, IR spectroscopy, electron microprobe and chemical analysis. Their thermal behavior was studied by
the DTA measurements. The heat capacities of the phosphates were measured between temperatures 7 and 650 K. The fractal dimensions
for the phosphates were calculated. The obtained thermodynamic characteristics of these phosphates and also literature data
for the compounds of NZP type structure are summarized.
The heat capacities of selected inorganic binary and ternary alkali metal compounds are determined using differential scanning calorimetry (DSC). As part of an ongoing research program at Battelle Memorial Institute since 1983, the heat capacities of cesium and rubidium chalcogenides, aluminates, silicates and uranates in the temperature range 310 to 800 K have been added to the series of compounds. The measured data is to be combined with the standard enthalpies of formation and low temperature heat capacities to obtain reliable thermodynamic data on the alkali metal compounds to high temperatures.
Authors:Luiza Arakaki, Maria da Fonseca, J. Espínola, A. Wanderley, E. Martins, T. Arakaki, and C. Airoldi
The reaction of cyclic ethylene sulfide with 3-aminopropyltrimethoxysilane resulted in a new silylating agent, which was anchored
onto a silica surface via the sol-gel procedure using hydrochloric acid or ammonium hydroxide as acid or base catalysts, respectively.
Both organofunctionalized surfaces have the ability to adsorb divalent cations from aqueous nitrate solution. Through calorimetric
titrations, the thermodynamic data of cation-basic center interactions were obtained. Exothermic enthalpy values were obtained
for all interaction processes. The calculated free Gibbs energy is in agreement with the spontaneity of the reactions and
the positive entropy values for all reactions are favorable for these systems.
Micelle/water partition coefficients were obtained for procaine hydrochloride using micellar liquid chromatography (MLC) to
illustrate the potential application of this technique to compounds of pharmaceutical interest. Experiments were conducted
over a temperature range which led to calculation of a Gibbs free energy, enthalpy and entropy of transfer for procaine hydrochloride.
Successful application of this technique was confirmed using a second compound over a range of temperatures, namely caffeine.
Overall, this work confirms that MLC can be used to determine precise and accurate partition coefficients that possibly more
closely mimic biological membranes than traditional in vitro systems, namely octanol/water.
Vic-dioxime ligandsand their metal complexes are used in analytical, bio, pigment and medicinal chemistry. Complexes of nickel(II),
copper(II), and cobalt(II) with benzylamino-p-chlorophenylglyoxime (BpCPG) are synthesised. Thermal behaviour of these complexes was studied in dynamic nitrogen atmosphere by DTA, DTG and TG techniques.
GC-MS combined system was used to identify the products during pyrolytic decomposition. The pyrolytic end products were identified
by X-ray powder diffraction. Thermoanalytical data of these complexes are presented in this communication. Interpretation
and mathematical analysis of these data and evaluation of order of reaction, the energy and entropy of activation based on
the integral method using the Coats-Redfern equation and the approximation method using the Horowitz-Metzger equation are
also given. The metal complexes undergo decomposition in three stages and metal oxides remained as end products of the complexes.