Thermodynamic Characteristics of a Series of Antimony Compounds: Standard Formation Enthalpy of Antimony Oxychloride SbOCl

The present work opens a series of publications devoted to the description of the results of determination or clarification of the formation enthalpies of certain antimony compounds that are of significant applied interest to science and technology. The measurement results of enthalpy of interaction crystalline SbCl3 and water with formation of crystalline SbOCl are given. On the basis of the obtained and literature data, the value of standard formation enthalpy of the product of this interaction --- antimony oxychloride SbOCl at temperature 298.15 K is calculated. This value coincided with the reference values within the margin of error. An attempt was made to determine the dissolution enthalpy of SbCl3 in a two-molar aqueous solution of hydrochloric acid: the obtained approximate value of this characteristic was --30 ± 2 kJ/mol

Synthesis and Evaluation of Thermodynamic Solubility of Triazolo Quinolone Class Derivatives in Various Solvents at 298.15-328.15 K

The solubility of triazolo quinolone class derivatives in methanol, ethanol, n-propanol, n-butanol and ethyl acetate was measured using a gravimetrical method at temperature ranging from 298.15 K to 328.15 K. The results of these measurements were correlated with semi empirical equations. Some thermodynamic parameters such as dissolution enthalpy, Gibb’s free energy and entropy of mixing have also been calculated.

Determination of the Solubility, Dissolution Enthalpy, and Entropy of Icariin in Acetone, Acetoacetate, Chloroform, and Light Petroleum

The solubility of icariin in acetone, acetoacetate, chloroform, and light petroleum in the 283.2‐318.2 K range was measured by ultraviolet-visible spectrophotometry. As the temperature increased, the solubility of icariin in the 4 solvents gradually increased. The solubility data correlated with the modified Apelblat equation. The dissolution enthalpy and entropy of icariin were determined using van’t Hoff plots. The dissolution enthalpy and entropy of icariin in the 4 solvents increases as acetone >acetoacetate >chloroform >light petroleum, which can be explained by the difference of the polarity indices between them. The polarity indices of the solvents affect the solubility behavior.

Solubility of dicarbohydrazide bis[3-(5-nitroimino-1,2,4-triazole)] in common pure solvents and binary solvents at different temperatures

The solubility of dicarbohydrazide bis[3-(5-nitroimino-1,2,4-triazole)] (DCBNT) was first measured under the different pure solvents and binary solvents by the dynamic method over the temperature range of 290–360 K at atmospheric pressure. Results in all the solvents were positively correlated with temperature, namely increased with increasing temperature. The experiment data were correlated by the Apelblat equation, the Yaws equation and the polynomial equation. The conclusion showed that these three models all agreed well with the experimental data. Simultaneously, the dissolution enthalpy, dissolution entropy and Gibbs free energy of DCBNT in different solvents were calculated from the solubility data by using the Apelblat model. The results indicate that the dissolution process of DCBNT in these solvents is driven by entropy, which provides theoretical guidance for further research on the crystallization of DCBNT.

Thermochemistry of Fullerene C60 Solutions in Toluene, o-Xylene and o-Dichlorobenzene

In hermetic highly sensitive calorimeter with an isothermal shell, the enthalpies of dissolution of fullerene C60 in toluene, o-xylene and o-dichlorobenzene were measured at temperatures of 288.15 K and 308.15 K at various concentrations of the dissolved substance. On the basis of the measured values and literature data, standard thermodynamic functions of the dissolution of C60 in the above mentioned solvents have been found at the indicated temperatures. The fact of the change in the sign of the dissolution enthalpy for all three systems under study at a transition to a temperature of 308.15 K has been revealed. A negative value of the dissolution entropy indicates the presence of a constant interaction in these liquid systems, which decreases sharply at 308.15 K.

DEPENDENCE OF DISSOLUTION ENTHALPY OF POLYVINYLPYRROLIDONE IN WATER ON ITS INITIAL MOISTURE CONTENT

Changes in integral and differential enthalpies of dissolution of polyvinylpyrrolidone (PVP) of different molecular weight in water were determined as a function of initial moisture content of the polymer. Hydration numbers were calculated.