Thermodynamic Properties in Gold Phenylacetylide in the Range 0-330 K

The temperature dependence of the heat capacity of gold phenylacetylide in the range 13-330 K was measured in an adiabatic vacuum calorimeter with an accuracy of 0.3%. These data were used for calculating the thermodynamic functions C _p0(T), H ⁰(T) - H ⁰(0), S ⁰(T) - S ⁰(0), and G ⁰(T) - H ⁰(0) for the range 0-330 K. The standard entropy of formation _f S ⁰ of gold phenylacetylide from the elements at T 298.15 K and p 101.325 kPa was calculated. The thermodynamic properties of gold phenylacetylide and related silver and copper compounds were compared.     

Thermodynamic Properties of N-(Trimethylsily)ethyleneimine N-(Triethylsily)ethyleneimine and (Dimethylphenylsilyl)ethyleneimine Complexes with Zinc Chloride in the Range 0-340 K

Tmperature dependence of heat capacity of N-(trimethylsilyl)ethyleneimine, N-(triethylsilyl)-ethyleneimine, N-(dimethylphenylsilyl)ethyleneimine with zinc chloride was studied in the 5-340 K rangein an adiabatic vacuum calorimeter with 0.2% error. From the data obtained tge complexes thermodynamicfunctions C0 _p(T), H ⁰(T)-H ⁰(0), S ⁰(T)-S ⁰(0) and G ⁰(T)-H ⁰(0) are obtained in the 0-340 K, as well as fractal dimensions D and characteristic temperatures max for the functions of gractal heat capacity of solid substances.     

Thermodynamic functions of α,α-trehalose dihydrate and of α,β-trehalose monohydrate at temperatures from 13 K to 300 K

Thermodynamic properties at low temperatures were investigated for α,α-trehalose dihydrate and α,β-trehalose monohydrate. The heat capacities were measured using an adiabatic calorimeter at temperatures between 13 K and 300 K. The heat capacity data were expressed as a function of temperature, T, by a polynominal of forth to sixth order, with which thermodynamic functions, enthalpy, entropy, and Gibbs free energy, were determined.     

VTx Properties of the System Water-2-Propanol in the Range 275.15-338.15 K

Densities and volume expansivities were obtained for the system water-2-propanol was measured in the range 275.15-338.15 K at atmospheric pressure over the entire range of compositions. The volume expansivities are much dependent on the composition of the mixture in the range 0-0.15 mole fractions of 2-propanol.     

Thermodynamic properties of chitosan-based hydrogels in the range 0–350 K

The heat capacity, the temperature, and the enthalpy of physical transformations of hydrogels based on the copolymer of acrylamide and chitosan with N,N-methylene-bis(acrylamide) as a crosslinking agent, hydrogels based on the mixture of poly(vinylpyrrolidone) and chitosan with glutaric aldehyde as the crosslinking agent, and dehydrated hydrogels has been studied in the range 85–350 K with the use of adiabatic vacuum calorimetry. The temperatures and enthalpies of melting of free water in hydrogels have been determined. From the experimental data obtained, the thermodynamic functions C° _p (T), H° (T) ? H°(0), S° (T) ? S°(0), and G° (T) ? H°(0) have been calculated for the temperature range 0–350 K. The ratio of free and bound water in the hydrogels under study has been determined by calorimetry.     

Thermodynamic Properties of Alkanediols+Acetates at 298.15 K

In this work we present experimental values of the density, refractive index, speed of sound, isentropic compressibility and liquid-liquid equilibria of the binary mixtures (methyl acetate, ethyl acetate, propyl acetate, and butyl acetate) with (1,2-ethanediol, 1,2-propanediol, or 1,3-propanediol) at 298.15 K and atmospheric pressure, as a function of mole fraction. From the experimental values, the corresponding excess and deviation values were computed (excess molar volumes, changes of refractive index on mixing, and changes of isentropic compressibility), variable-degree polynomials being fitted to the results. The validity of different estimation methods for predicting the experimental values of physical properties was tested. The limiting partial excess molar volume of the components in each binary mixture was determined by means of predetermined Redlich-Kister parameters. Group contribution method (UNIFAC-Dortmund) was applied in order to compare their capability in predicting the experimental equilibria values. This revised version was published online in July 2006 with corrections to the Cover Date.     

p-V m-x Properties of Water-Dimethylformamide System at 288.15 K over the Pressure Range 0.1-100 MPa

The compressibility factors k ((p ₀) - ta;(p))/ta;(p ₀ )) of water-dimethylformamide (DMF) binary mixtures are measured over the entire concentration range at 288.15 K and pressures of up to 100 MPa with a constant-volume piezometer. The specific and molar volumes in the water-DMF system are estimated as well as the isothermal compressibility coefficient s and excess and partial molar volumes of the system components. The composition dependence of the specific volume in the water-DMF system has extrema, its shape being pressure-dependent; such a dependence of the compressibility factor passes through a minimum; and the partial coefficient of the isothermal compressibility of water has an inversion point.     

Analytical Expressions of Thermodynamic and Transport Properties of the Martian Atmosphere in a Wide Temperature and Pressure Range

Calculation of thermodynamic and transport properties of CO₂/N₂/O₂/Ar system (Martian atmosphere) have been performed in a wide pressure (0.01–100 bar) and temperature range (50–50,000 K). A self-consistent approach for the thermodynamic properties and higher order approximation of the Chapman–Enskog method for the transport coefficients have been used. Debye–Hückel corrections have been included in the calculation of thermodynamic properties while collision integrals derived following a phenomenological approach and accounting also for resonant processes contributions have been used. Moreover, charge–charge interactions have been obtained by using a screened Coulomb potential. Calculated values have been fitted by closed forms ready to be inserted in fluid dynamic codes in order to simulate plasma conditions for different technological applications. Comparison with data present in literature is also reported.     

Volume Properties of the H2O-DMF Mixture at the Pressure 0.101 MPa in the Temperature Range 278.15-323.15 K

The density of the water-N,N-dimethylformamide mixture throughout the entire range of compositions in the temperature range 278.15-323.15 K at atmospheric pressure (0.101 MPa) was measured. The coefficients of thermal dilatation were calculated. The value strongly depends on the composition of the mixture in the range 0 < X <: 0.3 (X is the molar fraction of dimethylformamide), which is associated with breakdown of water structure. An equation relating the molar volume of the water-dimethylformamide mixture to the composition of the mixture and to the temperature was proposed.     

Behavior of rate coefficients for ion-ion mutual neutralization, 300-550 K

Rate coefficients k(MN) have been measured for a number of anion neutralization reactions with Ar(+) and Kr(+) over the temperature range 300-550 K. For the first time, the data set includes anions of radicals and other short-lived species. In the present paper, we review these results and make note of correlations with reduced mass, electron binding energy of the anion (equivalent to the electron affinity of the corresponding neutral), and temperature, and compare with expectations from absorbing sphere models. An intriguing result is that the data for diatomic anions neutralized by Ar(+) and Kr(+) have k(MN) values close to 3 × 10(-8) cm(3) s(-1) at 300 K, a figure which is lower than those for all of the polyatomic anions at 300 K except for SF(5)(-) + Kr(+). For the polyatomic anions studied here, neutralized by Ar(+) and Kr(+), the reduced mass dependence agrees with theory, on average, but we find a stronger temperature dependence of T(-0.9) than expected from the theoretical E(-0.5) energy dependence of the rate coefficient at thermal energies. The k(MN) show a weak dependence on the electron binding energy of the anion for the polyatomic species studied.     

Heat Capacities and Thermodynamic Properties of a H2O + Li2B4O7 Solution in the Temperature Range from 80 to 356 K

The molar heat capacities of an aqueous Li₂B₄O₇ solution were measured with a precision automated adiabatic calorimeter in the temperature range from 80 to 356 K at a concentration of 0.3492 mol⋅kg⁻¹. The occurrence of a phase transition was determined based on the changes in the curve of the heat capacity with temperature. A phase transition was observed at 271.72 K corresponding to the solid-liquid phase transition; the enthalpy and entropy of the phase transition were evaluated to be Δ H _m = 4.110 kJ⋅mol⁻¹ and Δ S _m = 15.13 J⋅K⁻¹⋅mol⁻¹, respectively. Using polynomial equations and thermodynamic relationship, the thermodynamic functions [H _T −H _298.15] and [S _T −S _298.15] of the aqueous Li₂B₄O₇ solution relative to 298.15 K were calculated in temperature range 80 to 355 K at intervals of 5 K. Values of the relative apparent molar heat capacities of the aqueous Li₂B₄O₇ solution, C _p,φ, were calculated at every 5 K in temperature range from 80 to 355 K from the experimental heat capacities of the solution and the heat capacities of pure water.     

2-氨基-4，6-二甲氧基嘧啶的低温热容和热力学性质研究

通过精密自动绝热量热计测定了自行合成并提纯的2-氨基-4，6-二甲氨基嘧啶 在78-394 K温区的摩尔热容。实验结果表明，该化合物有一个固-液溶化相变，其 熔化温度、摩尔熔化焓以及摩尔熔化熵分别为：（370.97 ± 0.02）K，（29853. 91 ± 9.25） J·mol~(-1)和（80.45 ± 0.03）J·mol~(-1) · K~(-1)。通过分 步熔化法得到样品的纯度为0.9984 (摩尔分数)和绝对纯样品的熔点为371.031 K。 在热容测量的基础上计算出了该物质每隔5K的热力学函数值。DSC技术对基固-溶熔 化过程作了进一步研究，结果与热容试验相一致。     

Thermodynamic and Electrophysical Properties of Nanosized LaMeFeCrMnO6.5 (Me = Li,Na, K) Ferro-Chromo-Manganites

Russian Journal of Physical Chemistry A - Ferro-chromo-manganites with compositions LaMeFeCrMnO6.5 (Me = Li, Na, K) are synthesized via ceramic technology from La2O3 (special purity grade), Fe2O3,...     

298.15和308.15 K温度条件下甘氨酰甘氨酸在电解质溶液中的热力学性质的研究:体积性质

利用精密数字密度计测定了298.15和308.15 K甘氨酰甘氨酸在KCl-水和NaCl-水混合溶剂中的密度, 计算了甘氨酰甘氨酸的表观摩尔体积V_Φ和极限偏摩尔体积V_Φ^?, 得到了其由纯水溶剂转移至混合溶剂中的迁移偏摩尔体积Δ_trsV_Φ^?和理论水化数N_h. 正的迁移偏摩尔体积说明在本文所研究的浓度范围内盐溶液可以提高球形蛋白的结构稳定性. 结果表明, 温度对迁移偏摩尔体积的影响很小; 溶液中离子与甘氨酰甘氨酸带电中心间的相互作用占主导地位. 利用共球交盖模型对结果进行了讨论.     

Effect of orientation,anisotropy, and water on the relaxation behavior of nylon 6 from 4.2 to 300°K

The relaxation behavior of nylon 6 from 4.2 to 300°K was investigated as a function of orientation, anisotropy and moisture content by using an inverted free-oscillating torsion pendulum. Three new relaxations, δ at 53°K, ? below 4.2°K, and ζ at 20°K, were discovered. The characteristics of these new relaxations strongly depend on the orientation anisotropy, and concentration of adsorbed water in the specimens. The results suggest that the mechanism of the γ process is associated with the motions of both the polar and methylene units. The mechanism of the β relaxation is postulated to originate with motions of both non-hydrogen-bonded polar groups and polymer—water complex units. The behavior of the α peak is consistent with the hypothesis that it originates with the rupture of interchain hydrogen bonding due to the motions of long-chain segments in the amorphous regions. Finally, the data strongly support the proposition that two types of water, tightly bound and loosely bound, exist in nylon 6.     

Laser Raman spectroscopy of THF clathrate hydrate in the temperature range 90-300 K

In situ Raman and Fourier transform infrared (FTIR-NIR) spectroscopic studies on tetrahydrofuran (THF-C(4)H(8)O) clathrate hydrate (CH) were reported. The Raman results in lattice (64 cm(-1)), ring breathing and C-H stretching mode regions are in conformity with earlier reports, while the FTIR (NIR) studies in second order mode region were reported for the first time. Comparison of the results indicate that the band assigned to ring breathing mode around 922 cm(-1) (in Raman) and corresponding second order mode in NIR around 4295 cm(-1) broadens and shifts in enclathrated THF. The ring breathing mode at lower temperatures (T<120 K) is highly asymmetric and splits into two and are due to different host-guest interactions at lower temperatures.     

Isothermal vapor-liquid equilibria for methanol and 2,3-dimethyl-2-butene at 343.15 K, 353.15 K, 363.15 K, 373.15 K

Isothermal vapor-liquid equilibrium (VLE) data were measured for the binary system methanol and 2,3-dimethyl-2-butene at 343.15 K, 353.15 K, 363.15 K, 373.15 K, respectively. The measurements were carried out in a novel recirculation equilibrium equipment. Three activity coefficient models including Wilson, NRTL and UNIQUAC, as well as the Soave-Redlich-Kwong equation of state were used to correlate the experimental data. The correlation results showed that a good consistency between the experimental data and the Wilson model can be achieved.