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Abstract  

A new complex, diaquadi(1,2,4-triazol-5-one)zinc(II) ion nitrate formulated as {[Zn(TO)2(H2O)2](NO3)2}n (1) (1,2,4-triazole-5-one, abbreviated as: TO) was synthesized and characterized by elemental analysis, X-ray single crystal diffraction, infrared spectrum (IR), differential scanning calorimetry (DSC), thermogravimetric analysis and differential thermogravimetric analysis (TG-DTG). The X-ray structure analysis reveals that the complex is orthorhombic with space group Pbca and unit-cell parameters a=6.9504(2) �; b=10.6473(3) �; c=17.8555(5) �. Based on the result of thermal analysis, the thermal decomposition process of the compound was derived. From measurement of the enthalpy of solution in water in 298.15 K, the standard molar enthalpy of solution of lignand TO and the complex were determined as 15.43�0.18 and 52.64�0.42 kJ mol−1, respectively. In addition, the standard molar enthalpy of formation of TO(aq) was calculated as −126.97�0.72 kJ mol−1.

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Table 3 have been used for calculating their standard enthalpies of solution. The solution enthalpy of Bu 4 NBr in FA measured by us Δ sol H 0 = 17.71 ± 0.02 kJ mol −1 at 298.15 K is in good agreement with the value 17.65 ± 0.05 [ 4

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.15 and 313.15 K, (ii) to calculate the values of their standard enthalpies of solution, (iii) to use the enthalpies of solution data to calculate the change in molar heat capacities, Δ C p 0 , for dissolution in mixed solvent, (iv) to compute the enthalpy

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Abstract  

Enthalpies of solution of 15-crown-5 (15C5) in the mixtures of water with acetonitrile (AN) or propan-1-ol (PrOH) and benzo-15-crown-5 ether (B15C5) in the PrOH-water mixtures have been measured at 298.15 K. The values of standard enthalpies of solution of 15C5 are negative in the mixtures of water with AN within the whole range of mixture composition and in the mixtures water-PrOH for water content x w>0.1 and those of B15C5 are positive (except the standard enthalpy of B15C5 in pure water) in the system water-PrOH. The results of the calorimetric measurements together with the earlier data for B15C5 in water-acetonitrile mixtures are discussed with regard to the intermolecular interactions that occur in these systems.

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Abstract  

The heats of solution of tetrabutylammonium bromide have been measured in mixtures of formamide (FA) with methanol (MeOH) and ethylene glycol (EG) at 313.15 K by calorimetric method. The standard enthalpies of solution in binary mixtures have been extrapolated to infinite dilution by Redlich–Rosenfeld–Meyer type equation using the literary data at 298.15 K and the present paper data at 313.15 K. The Debye–Hückel limiting law slope A H required for calculation of the ∆sol H 0 value has been obtained with application the new additive scheme of determination of the physic-chemical characteristics of binaries. The scheme is tested on the example of Bu4NBr solutions in FA–MeOH mixture at 298.15 K. Its application yields the ∆sol H 0 value very closed on the ones determined with the real (non-additive) characteristics of binaries. The standard enthalpies of solution extrapolated by Redlich–Rosenfeld–Meyer type equation are in a good agreement with the ones computed in terms of the Debye–Hückel theory in the second approximation. The heat capacities characteristics of Bu4NBr have been calculated in H2O–FA, MeOH–FA and EG–FA mixtures using the literary and present data. The sequence of solvents H2O > FA > EG > MeOH located on their ability to solvophobic solvation found by us earlier for enthalpic characteristics is confirmed by the ∆C p 0 values. The comparison of thermochemical characteristics of Bu4NBr solutions in aqueous and non-aqueous mixtures containing FA has been carried out. The own structure of water remains in the region of small additions of formamide to co-solvents. It considerably differs the H2O–FA mixture from the investigated non-aqueous systems.

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has been ±1%. The measurement of solution enthalpies of proline had been carried out within the range from 0.01 to 0.024 mol proline kg −1 aqueous urea solvent. The standard enthalpies of solution of l -proline in aqueous urea solutions

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Mettler AE 240 balance within the precision ±10 −5 g (buoyancy corrections to the weights were (±2 × 10 −5 g). The standard enthalpies of solution of l -α-amino acids (A) were determined by the linear extrapolation to zero concentration of the results

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hydroxyapatite [ 28 ]. Figure 6 shows the variation of the standard enthalpy of dissolution of the studied compounds versus the rate of CO 3 2− ion per unit cell. Table 4 Standard enthalpy of solution of the

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2 Standard enthalpies of solution at 298 K of “A” type carbonate phosphobaryum hydroxyapatites in 3 wt% HNO 3 and the corresponding error ‘∊’ Chemical formula m /mg d /mm −Δ H i /J ∊ i /J −Δ sol H /kJ/mol Ba 10 (PO 4 ) 6 (OH) 2 88.6 48.5 15.53 0

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∞ (NaI) = −32.35 kJ mol −1 (−31.88 [ 10] , −32.05 kJ mol −1 [ 17] ), in water Δ sol H ∞ (NaI) = −7.61 kJ mol −1 (−7.58 [ 5] , −7.62 kJ mol −1 [ 17] ). Table 1 Standard enthalpies of solution, Δ sol H

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