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1.
Yu. D. Orlov E. M. Chernova M. Yu. Orlov V. V. Turovtsev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(10):1607-1610
The database on the enthalpies of formation (Δf H ○) of aliphatic acetyl radicals of the RC·(O) type is analyzed and extended. Δf H ○ values are estimated for the first time for three compounds on the basis of experimental data. The data were analyzed using the additive group approach with the determination and correction of parameters. Good correspondence between the Δf H ○(RC·(O)) values calculated according to parameters with experimental data is observed. 相似文献
2.
L. P. Ogorodova E. V. Nagornaya L. V. Mel’chakova M. F. Vigasina I. A. Baksheev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(12):1952-1954
A thermochemical study of natural aluminum hydroxosulfate Al2[(OH)4SO4] · 7H2O, aluminite (Nakhodka deposit, West Chukotka, Russia) is performed on a Tian-Calvet “Setaram” high-temperature heat-conducting microcalorimeter (France). The enthalpy of aluminite formation from simple compounds is obtained via the melt calorimetry of dissolution, Δf H ○(298.15 K) = ?4986 ± 21 kJ/mol. 相似文献
3.
N. N. Smirnova E. V. Kolyakina T. G. Kulagina D. F. Grishin 《Russian Chemical Bulletin》2013,62(10):2251-2257
The thermodynamic properties of a series of polystyrene samples with different molecular weights (M w was varied from 2.5·103 to 6.57·104) were studied by precision adiabatic vacuum, high-accuracy dynamic, and combustion calorimetry: temperature dependences of the heat capacity in a wide temperature range, thermodynamic characteristics of glass transition and glassy state under standard pressure, and energy of combustion. The thermodynamic functions C ○ p (T), H ○(T) - H ○(0), S ○(T) - S ○(0), and G ○(T) - H ○(0) of polystyrene with different molecular weights, enthalpies of combustion Δc H ○, thermodynamic parameters of formation from simple substances Δf H ○, Δf S ○, and Δf G ○ at T = 298.15 K, and parameters of their synthesis from monomers were calculated from the experimental data. The temperature dependences of the heat capacity for a region of 0–380 K, glass transition temperatures, and thermodynamic characteristics of formation and synthesis of polystyrene depending on its molecular weight were examined. 相似文献
4.
T. R. Usacheva Fham Thi Lan V. A. Sharnin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(4):607-611
Using data from calorimetric titration, standard thermodynamic parameters logK ○, Δr G ○, Δr H ○, and TΔr S ○ of the formation of 18-crown-6 ether (18C6) molecular complex with triglycine (3Gly), [3Gly18C6] in H2O-EtOH solvents with contents of ethanol x ranging between 0.0 and 0.5 mole fractions are calculated. Increasing the concentration of EtOH in the solvent is found to raise the reaction’s exothermicity from ?5.9 to ?21.0 kJ mol?1 and logK ○ [3Gly18C6] from 1.10 to 2.53. A comparative analysis of the effect the composition of H2O-EtOH solvent has on the reactions of [3Gly18C6] and [Gly18C6] formation is performed. As in case of [Gly18C6] formation, the changes in the complex’s enthalpy of solvation Δtr H ○([3Gly18C6]) are close to the Δtr H ○(18C6) parameter and differ considerably from the Δtr H ○(3Gly) value, testifying to the crucial role 18C6 plays in changing the [3Gly18C6] state of solvation. The ratio between solvation contributions from reagents to Δtr G ○ of [3Gly18C6] formation is found to differ from that the one between the corresponding contributions to Δtr H r o : in transferring from water to H2O-EtOH mixtures, the increase in the positive Δtr G ○(18C6) values is slight and therefore negligible when compared to Δtr G ○(3Gly). 相似文献
5.
The enthalpies of formation (ΔH f o) for 24 hydrocarbon radicals (R?), mainly polycyclic aromatic radicals with the complex structure, were determined from the published data on bond dissociation energies. The ΔH f o values of the corresponding molecules were calculated, in the majority of cases, by the macroincrement method. Calculations by the group contribution method were performed. Some ΔH f o(R?) values were compared to those calculated by the additive-group method. Calculations were performed, and the conjugation energies of the radicals were discussed. The errors of determination of the ΔH f o(R?) values found were estimated. Due to this work, the database for ΔH f o values of hydrocarbon radicals was increased more than by 25%. 相似文献
6.
I. A. Kuz’mina M. A. Volkova K. A. Sitnikova V. A. Sharnin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(1):62-64
Heat effects of dissolution of piperidine (ppd) are measured by calorimetry at 298.15 K over the range of composition of acetonitrile-methanol (AN-MeOH) mixed solvents. Based on the Δsol H ○(ppd)AN-MeOH values obtained using the literature data on Δsol H ○ (ppd) in acetonitrile-dimethylsulfoxide (AN-DMSO) mixed solvents and the vaporization enthalpy of ppd, the enthalpies of solvation of amine in AN-MeOH and AN-DMSO binary mixtures are calculated. A rise in the exothermicity of solvation of piperidine is observed upon the transition from AN to DMSO and MeOH, due mainly to the enhanced solvation of the amino group of ppd as a result of changes in the acid-base properties of the mixed solvent. 相似文献
7.
I. N. Mezhevoi V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(12):2023-2026
Integral enthalpies of dissolution Δsol H m of DL-valine are measured via calorimetry of dissolution in aqueous solutions of glycerol, ethylene glycol, and 1,2-propylene glycol. Standard values of the enthalpies of dissolution (Δsol H ○) and transfer (Δtr H ○) of amino acid from water to mixed solvent are calculated from the resulting experimental data. The enthalpy coefficients for pair interactions hxy of amino acid with polyatomic alcohol molecules are calculated using the McMillan-Meyer theory and have positive values. The obtained results are discussed in light of the theory of the predomination of various types of interactions in mixed solutions and the effect of structural features of interacting biomolecules on the thermochemical parameters of the dissolution of amino acids. 相似文献
8.
G. G. Gorboletova A. A. Metlin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(9):1514-1518
The heat effects of the formation of Ni(II) complexes with L-histidine in an aqueous solution are determined via direct calorimetry at 298.15 K and ionic strengths of 0.2, 0.5, and 1.0 (KNO3). The standard thermodynamic characteristics (Δr H ○, Δr G ○, Δr S ○) of complex formation in the investigated system are calculated. It is concluded that the resulting values are consistent with the results from studying the structure of L-histidine complexes with Ni2+ ions by various spectral methods. 相似文献
9.
The enthalpy of formation at 298.15 K of the polymer Al13O4(OH)28(H2O)3+8 and an amorphous aluminium trihydroxide gel was studied using an original differential calorimetric method, already developed for adsorption experiments, and aluminium-27 NMR spectroscopy data. ΔHf “Al13” (298.15 K) = ? 602 ± 60.2 kJ mole?1 and ΔHf Al(OH)3 (298.15 K) = ? 51 ± 5 kJ mole?1. Using theoretical values of ΔGR “Al13” and ΔGR Al(OH)3, we calculated ΔGf “Al13” (298.15 K) = ? 13282 kJ mole?1; ΔSf “Al13” (298.15 K) = + 42.2 kJ mole?1; ΔGf Al(OH)3 (298.15 K) = ? 782.5 kJ mole?1; and ΔSf Al(OH)3 (298.15 K) = + 2.4 kJ mole?1. 相似文献
10.
I. N. Mezhevoi V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(4):589-592
Integral enthalpies of dissolution Δsol H m of L-alanine and L-serine are measured via the calorimetry of dissolution in aqueous solutions of xylitol, D-sorbitol, and D-mannitol. Standard enthalpies of dissolution (Δsol H ○) and the transfer (Δtr H ○) of amino acids from water to binary solvent are calculated from the experimental data. Using the McMillan-Mayer theory, enthalpy coefficients of pairwise interactions h xy of amino acids with molecules of polyols are calculated that are negative. The obtained results are discussed within the theory of the prevalence of different types of interactions in mixed solutions and the effect of the structural features of interacting biomolecules on the thermochemical parameters of dissolution of amino acids. 相似文献
11.
V. M. Smolyakov D. Yu. Nilov V. V. Grebeshkov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(7):1180-1185
An additive scheme with 11 constants is derived from the coefficients of characteristic polynomials (CCPs) of adjacency matrix A of irregular molecular graphs (IMG) for molecules that contain a bivalent heteroatom -SH or -OH at the beginning of the chain. The structural significance of the CCPs to adjacency matrix A′ is established. Our formula is used to calculate the enthalpies of formation Δf H liq 298K ○ of liquid alkanethiols (mercaptanes) C n H2n + 1SH and Δf H liq 298K ○ of liquid saturated monoalcohols C n H2n + 1OH that remain unstudied experimentally. 相似文献
12.
Yu. V. Goryushkina A. S. Monaenkova A. A. Popova L. A. Tiflova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(5):697-701
The enthalpy of reaction between praseodymium metal and 1.07 n HCl and the enthalpy of solution of praseodymium trichloride in 1.07 n HCl and water were measured in a swinging isoperibol calorimeter at 298.15 K. The results were used to calculate the enthalpy of formation of the praseodymium ion in the state of an infinitely dilute aqueous solution, Δf H°298.15 Pr3+(sln, ∞H2O) = ?687.8 ± 1.7 kJ/mol. 相似文献
13.
Yu. D. Orlov E. M. Chernova V. V. Turovtsev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(2):175-183
A collection of data on enthalpies of the formation(Δf
H
o) of aliphatic carbonyl-containing radicals is analyzed and expanded. The Δf
H
o values for 29 carbonyl-containing radicals are determined for the first time, and are strongly revised for 17 carbonyl-containing
radicals using the literature data on the dissociation energies of the bonds in molecules. The data is analyzed on the basis
of the structureproperty (enthalpy of formation) relation within the additive-group approach, with the determination and specification
of the parameters. It is concluded that the Δf
H
o values of carbonyl-containing radicals calculated from the obtained parameters (a total of 96 compounds was considered) agree
well with the experimental data. 相似文献
14.
S. N. Solov’ev K. I. Shatalov A. Ya. Dupal 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(5):893-895
The enthalpies of reaction of crystalline Ca[NiF6](cryst.) with water and a diluted solution of alkali are measured at 298.15 K using an isothermal-shell calorimeter. Based on the obtained values and literature data and using two independent methods, the standard enthalpy of formation of the studied compound is determined (Δf H ○Ca[NiF6](cryst.) = ?1955 ± 7 kJ/mol). 相似文献
15.
A. V. Markin I. A. Letyanina N. N. Smirnova V. V. Sharutin O. V. Molokova 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1499-1502
For the first time, the energy of combustion Δc U of crystalline triphenylantimony bis(acetophenoneoximate) Ph3Sb(ONCPhMe)2 has been measured at T = 298.15 K using the isothermal combustion calorimeter with a stationary bomb. The standard molar enthalpy of combustion Δc Hº, the standard molar enthalpy Δf Hº, and free Gibbs energy Δf Gº of formation of the above oximate have been calculated. 相似文献
16.
Anwar Ali Nisar Ahmad Malik Sahar Uzair Maroof Ali Mohammad Faiz Ahmad 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(6):1053-1061
Micellization behavior of hexadecyltrimethylammonium bromide (HTAB) was investigated conductometrically in aqueous solutions containing 0.02 mol kg?1glycine (Gly), diglycine (Gly-Gly), and triglycine (Gly-Gly-Gly) as a function of surfactant concentration at different temperatures. The critical micelle concentration (CMC) of HTAB exhibits a decreasing trend as the number of carbon atoms increases from Gly to Gly-Gly-Gly, favoring the micelle formation. The values of CMC and the degree of counterion dissociation of the micelles were utilized to evaluate the standard free energy for transferring the surfactant hydrophobic chain out of the solvent to the interior of the micelle, ΔG HP ○ , free energy associated with the surface contributions, ΔG S ○ , standard free energy, ΔG m ○ , enthalpy, ΔH m ○ , and entropy, ΔS m ○ of micellization were also calculated. The results show that the micellization of HTAB in aqueous solutions as well as in aqueous Gly/Gly-Gly/Gly-Gly-Gly solutions is primarily governed by the entropy gain due to the transfer of the hydrophobic groups of the surfactant from the solvent to the interior part of the micelle. The CMC obtained by fluorometric method is in close agreement with those obtained conductometrically. Furthermore, decrease in the I 1/I 3 ratio of pyrene fluorescence intensity suggests the solubilization of the additives by the surfactant micelles and that this solubilization increases as the hydrophobicity increases from Gly to Gly-Gly-Gly. 相似文献
17.
E. P. Kirpichev I. N. Zyuzin V. V. Avdonin Yu. I. Rubtsov D. B. Lempert 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(9):1359-1362
The standard enthalpies of combustion Δc H o and formation Δf H o of seven alkoxy-NNO-azoxy compounds containing the-N+(O?)=NO-characteristic group were determined by combustion in a calorimetric bomb in the atmosphere of oxygen. The contribution of this group to the Δf H o enthalpies of the substances studied was calculated. The Δf H o enthalpies found by the method of group contributions were in satisfactory agreement with experimental data. 相似文献
18.
Razieh Sanavi Khoshnood Elaheh Hatami 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(13):2294-2299
The complex formation between 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane (Kryptofix-5) and Sn2+ ions was studied in pure acetonitrile (AN), dimethylformamide (DMF), 1,4-dioxane (DOX), and methanol (MeOH) and in acetonitrile-1,4-dioxane (AN-DOX), acetonitrile-dichloromethane (AN-DCM), acetonitrile-methanol (AN-MeOH), and acetonitrile-dimethylformamide (AN-DMF) binary mixed solvent solutions at different temperatures using conductometric method. 1: 1 [ML] complex is formed between the metal cation and ligand in most solvent systems but in the cases of AN-MeOH (MeOH = 90 mol %) binary mixture and in pure MeOH a 2: 1 [M2L] complex was observed, that is the stoichiometry of complexes may be changed by the nature of the medium. The stability order of the (Kryptofix-5·Sn)2+ complex in the studied binary mixed solvent solutions at 25°C was found to be AN-DOX > AN-DCM > AN-MeOH > AN-DMF and in the case of pure solvents at 25°C the sequence was the following: AN > DMF > DOX. A non-linear behavior was observed for changes of logK f of (Kryptofix-5·Sn)2+ complex versus the composition of the binary mixed solvents, which was explained in terms of solvent-solvent intractions and also by the preferential solvation of the f species involved in the complexation reaction. The values of standard enthalpy changes (ΔH c ○ ) for complexation reactions were obtained from the slope of the Van’t Hoff plots and the changes in standard entropy (ΔS c ○ ) were calculated from the relationship ΔG c, 298.15 ○ = ΔH c ○ ? 298.15ΔS c ○ . The results show that in most cases, the (Kryptofix-5·Sn)2+ complex is both enthalpy and entropy stabilized. 相似文献
19.
The enthalpy of sublimation of benzamide was obtained by calorimetry in the range 323<T (K)<350. From values of ΔHsub(T)=f(T), it was possible to determine ΔH0sub (298.15 K)=101.7±1.0 kJ mole?1. Using previous data on ΔH0f (c, 298.15 K) obtained by combustion calorimetry, the value of ΔH0f (g, 298.15 K)=?100.9±1.2 kJ mole?1 was calculated. With the use of energetical values concerning thioacetamide, thiobenzamide and thiourea, on the one hand, and acetamide, benzamide and urea, on the other, a comparative study was made. 相似文献
20.
Calorimetric measurements of the enthalpy of reaction of WO3(c) with excess OH?(aq) have been made at 85°C. Similar measurements have been made with MoO3(c) at both 85 and 25°C, to permit estimation of ΔH°=?13.4 kcal mol?1 for the reaction WO3(c)+2OH?(aq)=WO2?4(aq)+H2O(liq) at 25°C. Combination of this ΔH° with ΔH°f for WO3(c) leads to ΔH°f=?256.5 kcal mol?1 for WO2?4(aq). We also obtain ΔH°f=?269.5 kcal mol?1 for H2WO4(c). Both of these values are discussed in relation to several earlier investigations. 相似文献