Quantization Heat Capacity Equations at Constant Volume According to Energy Levels and Planck Constant

The quantization thermal excitation isotherms based on the maximum triad spin number (G) of each energy level for metal cluster were derived as a function of temperature by expanding the binomial theorems according to energy levels. From them the quantized geometric mean heat capacity equations are expressed in sequence. Among them the five quantized geometric heat capacity equations, fit the best to the experimental heat capacity data of metal atoms at constant pressure. In the derivations we assume that the triad spin composed of an electron, its proton and its neutron in a metal cluster become a basic unit of thermal excitation. Boltzmann constant (kB) is found to be an average specific heat of an energy level in a metal cluster. And then the constant (kK) is found to be an average specific heat of a photon in a metal cluster. The core triad spin made of free neutrons may exist as the second one additional energy level. The energy levels are grouped according to the forms of four spins throughout two axes. Planck constant is theoretically obtained with the ratio of the internal energy of metal (U) to total isotherm number (N) through Equipartition theorem.

Constant-Volume Heat Capacity of Mixed Supercritical Fluids and Molecular Interaction in the Systems

Constant-volume heat capacities of supercritical (SC) CO2, SC CO2-n-pentane, and SC CO2-n-heptane mixtures were determined at 308.15 K in the pressure range from 6 to 12 MPa. It was found that there is a maximum in each heat capacity vs pressure curve. Intermolecular interaction in the fluids was studied.

Elastic constants and thermodynamic properties of Mg_2Si_xSn_(1-x) from first-principles calculations

This paper stuides the elastic constants and some thermodynamic properties of Mg2SixSn1-x （x = 0, 0.25, 0.5, 0.75, 1） compounds by first-principles total energy calculations using the pseudo-potential plane-waves approach based on density functional theory, within the generalized gradient approximation for the exchange and correlation potential. The elastic constants of Mg2SixSn1-x were calculated. It shows that, at 273 K, the elastic constants of Mg2Si and Mg2Sn are well consistent with previous experimental data. The isotropy decreases with increasing Sn content. The dependences of the elastic constants, the bulk modulus, the shear modulus and the Debye temperatures of Mg2Si and Mg2Si0.5Sn0.5 on pressure were discussed. Through the quasi-harmonic Debye model, in which phononic effects were considered, the specific heat capacities of Mg2SixSn1-x at constant volume and constant pressure were calculated. The calculated specific heat capacities are well consistent with the previous experimental data.

Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C11H17NO（s）

This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO（s） have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO（s） relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

立方相BaTiO_3电子结构及物理性质的第一性原理计算

采用基于密度泛函理论的第一性原理平面波赝势法计算了立方相BaTiO3的电子结构、弹性常数、等容比热容和声子散射关系曲线.计算得到的立方相BaTiO3的弹性常数和热容与实验结果符合得很好.计算并详细分析了立方相BaTiO3沿高对称方向(X→R;R→M;M→G;G→R)的声子色散曲线.

Studies of Thermodynamic Properties and Relative Stability of Polybrominated Xanthones by Density Functional Theory

The thermodynamic properties of xanthone（XTH） and 135 polybrominated xanthones（PBXTHs） in the standard state have been calculated at the B3LYP/6-31G＊ level using Gaussian 03 program.The isodesmic reactions were designed to calculate the standard enthalpy of formation（△fHθ） and standard free energy of formation（△fGθ） of PBXTH congeners.The relations of these thermodynamic parameters with the number and position of Br atom substitution（NPBS） were discussed,and it was found that there exist high correlation between thermodynamic parameters（entropy（Sθ）,△fHθ and △fGθ） and NPBS.According to the relative magnitude of their △fGθ,the relative stability order of PBXTH congeners was theoretically proposed.The relative rate constants of formation reactions of PBXTH congeners were calculated,Moreover,the values of molar heat capacity at constant pressure（Cp,m） from 200 to 1000 K for PBXTH congeners were also calculated,and the temperature dependence relation of them was obtained,suggesting very good relationships between Cp,m and temperature（T,T^1 and T^2） for almost all PBXTH congeners.

DFT Study on Some Properties of Polybrominated Phenoxathiin 10-Oxides

With the B3LYP calculation method of density functional theory（DFT）and the 6-31G＊ basis set,full optimization calculation was made for phenoxathiin10-oxide（PTO）and 135 polybromine phenoxathiin 10-oxides（PBPTOs）with the Gaussian 03 program and molar heat capacity in constant volume（CVθ）value of each molecule in the standard state was obtained.The relation between CVθ and the substitution position and number of bromine atom（NPBS）was studied,and the results indicated good correlation（R2 = 1.000）between CVθ and NPBS of PBPTO compounds.Based on the output file of Gaussian 03 program,molar heat capacity at constant pressure（Cp,m）of PBPTO compounds from 200 to 1,000 K was calculated with the statistical thermodynamics program,and the correlation equation between Cp,m and temperature（T,T-1 and T-2）was obtained with the least-squares method,and the correlation coefficient of the correlation equation（R2）was 1.000.In addition,based on the partition function of each molecule calculated by vibration analysis,the relative rate constant of formation of each molecule was calculated.

Speed of Sound and Ideal-Gas Heat Capacity at Constant Pressure for HFC-125

The gaseous speed of sound, the ideal gas heat capacity at constant pressure, and the second Virial coefficient were determined for pentafluoroethane (HFC 125). A total of 49 data points of speed of sound for gaseous HFC 125 were measured for temperatures from 273 to 313 K and pressures from 32 to 479 kPa with a cylindrical, variable path acoustic interferometer. The ideal gas heat capacity at constant pressure and the second acoustic Virial coefficient were determined over the temperature range from the speed of sound measurements and were correlated as functions of temperature. An analytical expression for the second Virial coefficient derived using the square well intermolecular potential model was compared with the data.

变容积量热器法测量液体比热容实验研究

基于准稳态理论，建立了一种可以实时改变工作腔体容积的非流动型量热器，并自行搭建了比热容测量系统。通过测量温度为273．15～293．15K常压下纯水的比热容，对实验系统的测量精度及可靠性进行了检测。结果显示．该实验系统的相对偏差绝对平均值为0．35％，验证了该套实验系统设计原理的正确性及实验装置的准确性。此外，测量了4种配比下．含油制冷剂R134a在温度为273．15～293．15K，其饱和液体的比定压热容和比定容热容。

气体定压比热容测量实验教学系统开发

为了满足大学工程热力学课程的实验教学要求,针对传统实验装置因加热温差范围过大而导致实验结果不准确的问题,设计开发了一套新型气体定压比热容测定实验系统.设计的新型气体定压比热容测定实验系统通过结合预热段、保温、两次测量算法改进等方式,使实验结果更加准确可靠,真实地反映了实验原理,具有较高的精度,完全满足本科研究性实验教学要求.

用微扰理论计算磁场对低浓度磁性胶粒体系热力学性质的影响

The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.According to the low density system of magnetic colloidal particles in water,a theoretic model is set up based on perturbation theory.The relations between internal energy,specific heat of magnetic colloidal particles system and temperature,density of colloidal particles are calculated.The calculated results are useful in explaining the magnetic memory effect.

用恒流量热器测定水的比热容

介绍了用恒流量热器测定水的比热容的一种新方法.当达到稳定状态时,电阻丝中电流产生的热量等于流过的水吸收的热量与散逸到环境中的热量之和,利用两次独立的实验消去了散逸到环境中的热量这一未知因素,从而使实验结果的准确度得到显著地提高.

带冷凝热回收变容量恒温恒湿系统的研究

高能耗问题一直是恒温恒湿空调面临的难题。针对这一问题,设计了一种带冷凝热回收装置的变容量系统,将部分的冷凝热回收用于空气再热,节省了电能,减少了热污染。进行了可行性分析,介绍了系统的原理、控制方法、技术特点及发展前景。

流体液相定压比热容方程

An equation for the specific heat capacity of liquids which contains four constants hasbeen developed in this paper by means of analysis of data of heat capacities and properties offunction curves and its form is simple and convenient for use. It is testified that the equationhas good extrapolating property and so cp values of subcooled liquids which are deficient canbe predicted by that of saturated liquids and vice versa.

1,1,1,2,3,3,3─七氟丙烷的气相声速

分析了气相声速与理想气体比定压热容的热力学关系，用超声变程干涉仪测定了１，１，１，２，３，３，３－七氟丙烷（ＨＦＣ－２２７ｅａ）的 ７２组气相声速值，温度范围 ２７３－３３３ Ｋ，压力范围 ２６－３１５ ｋＰａ，测量不确定度小于 ０．０５％。根据这些实验数据，确定了ＨＦＣ－２２７ｅａ的理想气体比定压热容和声速第二维里系数，并分别拟合得到了与温度的函数，理想气体比定压热容的不确定度小于 ０．５％．使用方阱势能模型导出了 ＨＦＣ－２２７ｅａ的第二维里系数，并与文献值进行了比较。

DSC法测定联苯的热力学性质与纯度

利用差示扫描量热仪（DSC）对联苯的熔点、熔融焓、结晶焓进行测定，实验结果显示在不同升温／降温速率下DSC法对联苯的熔点的测定结果影响较大，而对熔融焓和结晶焓并无影响．测定联苯固体比定压热容（283．15～323．15K）、液体比定压热容（363．15～443．15K），并将比定压热容与温度进行关联，导出计算比定压热容的方程．同时介绍利用DSC测得联苯纯度的方法．

Lu(Et_2dtc)_3(phen)的生成反应焓变、摩尔热容和恒容燃烧能测定(英文)

A ternary solid complex Lu(Et2dtc)3(phen) has been obtained from the reaction of hydrated lutetium chloride with sodium diethyldithiocarbamate (NaEt2dtc), and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol. IR spectrum of the complex indicates that Lu3+ binds with sulfur atom in the Na(Et2dtc)3 and nitrogen atom in the o-phen. The enthalpy change of liquid-phase reaction of formation of the complex, △CHM- (l), was determined to be (-32.821 ± 0.147 ) kJ·mol-1 at 298.15 K by an RD-496 Ⅲ type heat conduction microcalormeter. The enthalpy change of the solid-phase reaction of formation of the complex, △CHM- (s), was calculated to be (104.160 ± 0.168) kJ · mol-1 on the basis of an appropriate thermochemistry cycle. The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, such as the activation enthalpy (△HM-), the activation entropy (?驻SM-), the activation free energy (△GM-), the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A) and the reaction order (n), were obtained by combination the reaction thermodynamic and kinetic equations with the data of thermokinetic experiments. The molar heat capacity of the complex, cm, was determined to be (82.23 ± 1.47) J·mol-1·K-1 by the same microcalormeter. The constant-volume combustion energy of the complex, ΔcU, was determined as (-17 898.228 ± 8.59) kJ·mol-1 by an RBC-Ⅱtype rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, △CHM-, and standard enthalpy of formation, △CHM-, were calculated to be (-17 917.43 ± 8.11) kJ·mol-1 and (-859.95 ±10.12) kJ·mol-1, respectively.

空气比热容比的标准值与测量的误差

在绝热膨胀过程中,用电磁阀、大口径管(φ≥4mm)迅速放气和关闭。对空气的比热容比γ的标准值进行了详细的论证计算1.3990<γ<1.4025,并对实测值的误差进行了分析讨论。

应用分子聚集模型计算醇类的气体热容及其缔合常数

应用分子聚集模型修正的维里方程导出计算气体热容的表达式,关联了11种汽相缔合的低级脂肪醇的气体热容与温度的关系,计算值与量热实验值符合得很好,表达出醇类气体热容的高度非理想性.在此基础上,求得醇的分子缔合平衡常数,与文献数据吻合.

HFC-125气相声速和理想气体比定压热容的研究

分析了气相声速与理想气体比定压热容的热力学关系 ,用超声变程干涉仪测定了HFC -12 5的 4 9组气相声速值 ,温度范围 2 73- 313K ,压力范围 32 - 4 79kPa。根据这些实验数据 ,获得了HFC - 12 5的理想气体比定压热容和声速第二维里系数 ,并分别拟合得到了理想气体比定压热容和声速第二维里系数与温度的函数关系。使用方阱势能模型导出了HFC - 12 5的第二维里系数 。