Thermodynamics of carbyne

Published data on the thermodynamic properties of carbyne are analyzed and generalized. The thermodynamic properties of carbyne are compared with the properties of other allotropic modifications of carbon (fullerenes, diamonds, and graphite). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 971–980, June, 2000.     

Thermodynamics of Lanthanum Uranovanadate

Temperature dependence of heat capacity in the range 80-300 K, as well as absolute entropy and standard formation enthalpy, entropy, and Gibbs function at 298.15 K were determined for La(VUO₆)₃&· 10H₂O by reaction and adiabatic vacuum calorimetry. Thermodynamic characteristics of dehydration, synthesis, and solution of the compound were calculated.     

Thermodynamics of patina formation

Changes in the standard Gibbs energies in reactions that occur in the interaction of copper and copper oxides with oxygen, water, and impurities contained in atmospheric precipitations were calculated.     

Thermodynamics of addition polymerization

Addition polymerizations of both acyclic and cyclic monomers show the characteristic features of any aggregation process, in particular, a ceiling temperature above which the formation of the aggregate (long‐chain polymer), under given conditions of monomer concentration, solvent, and pressure, would involve a positive change of free energy and is therefore impossible. Conversely, for a given temperature, pressure, and solvent, there is an equilibrium monomer concentration below which long‐chain polymer cannot be formed. Monomers must therefore have a negative free energy of polymerization, under given conditions, if they are to be capable of undergoing a significant extent of polymerization. The effect of monomer structure, including ring size, on thermodynamic polymerizability is discussed, as well as the possibility of copolymerizing monomers that cannot themselves give homopolymers. Examples are given for various possible mechanisms of polymerization. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2137–2146, 2000     

Thermodynamics of interface elasticity

We generalize and extend a series of articles on the thermodynamics of interface elasticity. The whole formulation is based on taking into account a finite elastic deformation. This leads to generalized forms of the equations for the surface excess of the internal energy, the Gibbs adsorption equation and the Shuttleworth equation. In all cases correction terms occur containing the strain tensor. Although the deformation might be small, the corrections are critical in performing derivatives with respect to the strain which are needed to obtain equations connecting measurable quantities. These consequences are demonstrated in detail for the simple case of the spherical electrode. In the traditional electrochemical treatment, the densities of extensive quantities are related to the deformed surface, which is usually not mentioned. In analogy to the theory of volume elasticity, where the densities are related to the unstrained solid, one can also relate the densities of surface excess quantities to the unstrained surface. This formulation gives at first an additional proof for some of the generalized equations. Moreover, within this formulation one can express the surface excess of the energy density by the superficial work of the unstrained surface and three surface elastic constants, two of them being the surface Lamé constants. In the alternative formulation, the Shuttleworth equation appears simply as the relation between a generalized force and a generalized potential. Published in Elektrokhimiya in Russian, 2009, Vol. 45, No. 1, pp. 78–86. The text was submitted by the authors in English. This study was prepared for the special issue devoted to the 100th anniversary of B.V. Ershler.     

Thermodynamics of tetraphenylantimony acetophenoneoxymate

In the present research for the first time, the heat capacity C_\textp ^° C_{\text{p}}^{ \circ } of crystalline tetraphenylantimony acetophenoneoxymate Ph₄SbONCPhMe has been measured using the methods of precision adiabatic vacuum calorimetry over the range from 6 to 350 K, the standard thermodynamic functions: heat capacity C_\textp ^° (T ) C_{\text{p}}^{ \circ } (T ) , enthalpy H°(T) − H°(0), entropy S°(T), and Gibbs function G°(T) − H°(0) have been calculated over the range from T → 0 K to 350 K. Low-temperature (20 K ≤ T ≤ 50 K) heat capacity data have shown a chain-layered structure topology of the compound under study. The energy of combustion of the compound has been determined in the isothermal combustion calorimeter with a stationary bomb. The standard thermodynamic functions of formation of crystalline Ph₄SbONCPhMe at 298.15 K have been calculated. The differential scanning calorimetry and thermogravimetric analysis studies have shown the compound melts with decomposition and its melting temperature has been estimated. Thermodynamic properties of Ph₄SbONCPhMe, Ph₅Sb and Ph₄SbONCPh₂ have been compared.     

Thermodynamics of polyether solutions

Measurements are reported of the vapor pressures and the heats and volumes of mixing of solutions of poly(ethylene glycol dimethyl ether) in chloroform and in carbon tetrachloride. The measurements have been used to calculate the thermodynamic mixing functions for mixing with zero volume change. These values have been compared with the predictions of the lattice theory of mixtures at three different levels of approximation, viz., the generalized “first approximation” theory of Barker, the “zeroth approximation” theory, and the Flory theory. In the hydrogen-bonding chloroform solutions the Barker theory is more successful than the other forms of the lattice theory. The results have also been used, in conjunction with those for solutions of poly(propylene glycol dimethyl ether) in the same two solvents, to test the ability of the Barker theory to correlate the properties of related systems. Good correlation is found between the two carbon tetrachloride solutions but not between the chloroform solutions. It is probable that the side-chain methyl groups in the propylene oxide repeating unit cause the hydrogen-bonding interaction to be weaker in this polymer than it is in the polymer with the ethylene oxide repeating unit.     

Thermodynamics of adsorption equilibrium

Russian Chemical Bulletin -     

Thermodynamics of polymer systems

This work gives an introduction into the thermodynamic modeling of polymer systems. After a short overview about the different basics of thermodynamic models, results obtained with the recently proposed PC-SAFT equation of state are discussed exemplarily for systems containing polymers as well as copolymers.     

Thermodynamics of azurin folding

The role played by the metal ion in thermodynamics of azurin folding was addressed by studying the thermal denaturation of the apo-form by differential scanning calorimetry (DSC), and by comparing the results with data concerning the holo protein. The thermal unfolding experiments showed that at 25°C the presence of metal ion increases the thermodynamic stability of azurin by 24 kJ mol⁻¹. A comparison between the unfolding and the copper binding free energies allow us to assert that the unfolded polypeptide chain binds copper and subsequently folds into native holo azurin, being this the thermodynamically most favourable process in driving azurin folding.     

Thermodynamics of supercooled water

We review the available experimental information on the thermodynamic properties of supercooled water and demonstrate the possibility of modeling these thermodynamic properties on a theoretical basis. We show that by assuming the existence of a liquid-liquid critical point in supercooled water, the theory of critical phenomena can give an accurate account of the experimental thermodynamic-property data up to a pressure of 150 MPa. In addition, we show that a phenomenological extension of the theoretical model can account for all currently available experimental data in the supercooled region, up to 400 MPa. The stability limit of the liquid state and possible coupling between crystallization and liquid-liquid separation are also discussed. It is concluded that critical-point thermodynamics describes the available thermodynamic data for supercooled water within experimental accuracy, thus establishing a benchmark for further developments in this area.     

Thermodynamics of nickel orthosilicate

The standard Gibbs free energy, enthalpy, and entropy of formation of nickel orthosilicate have been determined with the help of a solid-electrolyte galvanic cell involving Ni²⁺ exchanged β-alumina electrolyte. The results have been compared with those obtained by other authors.     

Thermodynamics of dye dimerization

The thermodynamic parameters for dimerization has been obtained for fluorescein and halo-fluorescein dyes. Results indicate an increasing contribution of hydrophobic bonding for more aggregating dyes.     

Thermodynamics of lattice heteropolymers

We calculate thermodynamic quantities of hydrophobic-polar (HP) lattice proteins by means of a multicanonical chain-growth algorithm that connects the new variants of the Pruned-Enriched Rosenbluth Method and flat histogram sampling of the entire energy space. Since our method directly simulates the density of states, we obtain results for thermodynamic quantities of the system for all temperatures. In particular, this algorithm enables us to accurately simulate the usually difficult accessible low-temperature region. Therefore, it becomes possible to perform detailed analyses of the low-temperature transition between ground states and compact globules.     

Thermodynamics of silver-thiosemicarbazide complexation

The stability constants of the complexes formed by the silver ion with thiosemicarbazide (tsc) are determined by a potentiometric method using a silver electrode, in a wide range of silver-ion overall concentration (from 10^?4 to 9 × 10^?3 mol dm^?3). Calorimetric measurements gave access to the enthalpy changes accompanying the formation of the species Ag(tsc)⁺, Ag₂(tsc)₃²⁺, Agtsc)₂⁺, and Ag(tsc)₃⁺, and the corresponding entropy changes have been calculated.     

Thermodynamics of polymer blends

The general principles of thermodynamic equilibrium in binary liquid systems are reviewed briefly, and extended to quasi-binary mixtures of polydisperse polymers. Molecular models allowing actual phase behaviour to be discussed in terms of molecular parameters are exposed to data on the system polystyrene/polyvinylmethylether. Disparity in size and share between the repeating units must be introduced to obtain reasonable agreement between theory and experiment. The neccessary introduction of the molar-mass distribution detracts from this agreement which makes clear that other aspects exist that must be taken into account. For example, cross association between repeating units has a marked effect on phase behaviour. Blends are subject to two kinds of thermodynamic aging which lead either to considerable mutual solubility in supposedly immiscible blends, or to metastable equilibria transforming into states of lower Gibbs energy. In both cases physical proerties of the blend will change with time.