水合邻苯二甲酸钠的合成、结构表征及热化学性质

选择邻苯二甲酸和氢氧化钠作为反应物,利用液相合成方法合成了水合邻苯二甲酸钠.利用X射线粉末衍射、化学与元素分析等方法表征了它的组成和结构.利用精密自动绝热热量计测定了该化合物在78～366K温区的摩尔热容.将该温区的摩尔热容实验值用最小二乘法拟合得到摩尔热容(Cp,m)对温度(T)的多项式方程,用此方程进行数值积分得到此温度区间内每隔5K的舒平热容值和相对于298.15K时的热力学函数值.另外,依据Hess定律,通过设计合理的热化学循环,利用等温环境溶解-反应热量计分别测量了固相量热反应的反应物和产物在所选溶剂中的溶解焓,从而确定反应的反应焓为:ΔrHm=29.073±1.05kJ·mol-1.最后,利用反应的反应焓和其它反应物和产物已知的热力学数据计算出水合邻苯二甲酸钠的标准摩尔生成焓为:-1493.637±1.11kJ·mol-1.     

4-硝基苯甲醇的低温热容和标准摩尔生成焓

用精密自动绝热量热计测定了4-硝基苯甲醇（4-NBA）在78 ~ 396 K温区的摩尔热容。其熔化温度、摩尔熔化焓及摩尔熔化熵分别为:(336.426 ± 0.088) K, (20.97 ± 0.13) kJ×mol-1 和 (57.24 ± 0.36) J×K-1×mol-1.根据热力学函数关系式,从热容值计算出了该物质在80 ~ 400 K温区的热力学函数值 [HT - H298.15 K] 和[ST - S298.15 K]. 用精密氧弹燃烧量热计测定了该物质在T＝298.15 K的恒容燃烧能和标准摩尔燃烧焓分别为 (C7H7NO3, s)＝- ( 3549.11 ± 1.47 ) kJ×mol-1 和 (C7H7NO3, s)＝- ( 3548.49 ± 1.47 ) kJ×mol-1. 利用标准摩尔燃烧焓和其他辅助热力学数据通过盖斯热化学循环, 计算出了该物质标准摩尔生成焓 (C7H7NO3, s)＝- (206.49 ± 2.52) kJ×mol-1 .     

邻苯二甲酸氢铵NH4(C8H5O4)(s)的低温热容和热化学研究

选择分析纯邻苯二甲酸和浓氨水为反应物,合成了邻苯二甲酸氢铵.利用元素分析、FTIR和X-射线粉末衍射技术表征了它的组成和结构.用精密自动绝热热量计测定了它在78～400 K温区的摩尔热容,将该温区的摩尔热容实验值用最小二乘法拟合,得到摩尔热容(Cp,m)随折合温度(X)变化的多项式方程,利用此方程计算出该温区内每隔5 K的舒平热容值和相对于298.15K的各种热力学函数值.另外,依据Hess定律,通过设计合理的热化学循环,利用等温环境溶解-反应热量计分别测定所设计反应的反应物和产物在所选溶剂中的溶解焓,得到该反应的反应焓为△rHθm=(1.787±0.514)kJ·mol-1.最后,利用此反应焓和反应中其他物质的热力学数据计算出邻苯二甲酸氢铵的标准摩尔生成焓为:△fHθm[NH4(C8H5O4),s]=-(912.953±0.628)kJ·mol-1.     

配合物Zn(Met)SO4·H2O(s)的低温热容和标准摩尔生成焓

利用精密自动绝热热量计直接测定了配合物Zn(Met)SO4·H2O(s)在78～370K温区的摩尔热容.通过热容曲线的解析得到该配合物的起始脱水温度为T0=329.50K.将该温区的摩尔热容实验值用最小二乘法拟合得到摩尔热容(Cp,m)对温度(T)的多项式方程,并且在此基础上计算出了它的舒平热容值和各种热力学函数值.依据Hess定律,通过设计热化学循环,选择体积为100cm3、浓度为2mol·L-1的盐酸作为量热溶剂,利用等温环境溶解-反应热量计,测定和推算出该配合物的标准摩尔生成焓为?fHms=-(2069.30±0.74)kJ·mol-1.     

电化学方法测定纳米材料的热力学函数

以纳米铜为例,首次采用电化学方法获取纳米材料的热力学函数.通过电化学沉积法制备了粒子尺寸约80nm的纳米铜电极,测定纳米铜与块体铜电极的电势差,以块体铜的热力学函数值为参考标准,根据纳米铜与块体铜的热力学关系式,求得纳米铜的标准摩尔生成焓、标准摩尔生成吉布斯自由能、标准摩尔熵分别为5.16kJmol-1、0.216kJmol-1、49.75JK-1mol-1,同时,求得纳米铜可逆电池反应的热效应为-4.95kJmol-1.     

水合烟酸钡的合成、结构表征和热化学性质

选择烟酸和氢氧化钡作为反应物,利用室温固相合成方法,借助于球磨技术,合成了一种新的化合物-水合烟酸钡.利用化学分析、元素分析、FTIR和X射线粉末衍射等方法确定了它的组成和结构为Ba(Nic)2·3H2O(s).利用精密自动绝热热量计直接测定了此化合物在78-400 K温区的摩尔热容.在热容曲线上出现了一个明显的吸热峰,通过对热容曲线的解析,得到了相变过程的峰温、相变焓和相变熵分别为(327.097±1.082)K、(16.793±0.084)kJ·mol-1和(51.340±0.164)J·K-1·mol-1将该温区的摩尔热容实验值用最小二乘法拟合得到摩尔热容(Cp,m)对温度(T)的多项式方程,并且在此基础上计算出了它的舒平热容值和各种热力学函数值.另外,依据Hess定律,通过设计合理的热化学循环,选择体积为100mL、浓度为0.5mol·L-1的盐酸作为量热溶剂,利用等温环境溶解-反应热量计分别测量固相反应的反应物和产物在所选溶剂中的溶解焓,利用溶解焓确定固相反应的反应焓为△rH0m=-(84.12±0.38)kJ·mol-1.最后,利用固相反应的反应焓和其它反应物和产物已知的热力学数据计算出水合烟酸钡的标准摩尔生成焓为△rH0m[Ba(Nic)2·3H2O(s)]=-(2115.13±1.90)kJ·mol-1.     

粒度对纳米体系化学反应热力学性质的影响

为了研究纳米粒子的粒度对化学反应热力学性质的影响规律, 以球形原子簇来模拟纳米金刚石颗粒, 用量子化学方法对粒度不同的金刚石纳米粒子与氧气反应的热力学性质进行了计算. 结果表明, 粒度对多相反应的标准摩尔反应焓△rH0m、标准摩尔反应熵△rS0m、标准摩尔反应吉布斯函数△rG0m和标准平衡常数K0均有明显的影响, 随着反应物粒径的减小, △rH0m、△rS0m和△rG0m均降低,而K0增大. 这些影响规律与实验结果基本一致.     

2-吡嗪羧酸银的合成、晶体结构及热化学性质

以二次蒸馏水为溶剂,合成了2-吡嗪羧酸银(Ag(pyza)(s)),并利用X-射线单晶衍射法表征了其晶体结构.根据晶体结构数据计算得到2-吡嗪羧酸银的晶格能为554.10 kJ/mol.利用TG/DSC热分析技术研究了该化合物的热分解过程;用精密自动绝热热量计测量了其在78~378 K温区的低温热容;通过最小二乘法拟合得到了摩尔热容随折合温度变化的多项式方程,利用此方程计算出该化合物的舒平热容和各种热力学函数.通过设计合理的热化学循环,利用等温环境溶解-反应热量计分别测定了所设计热化学反应的反应物和产物在选定溶剂中的溶解焓,通过计算得到反应的反应焓为:?(31.919±0.526)kJ/mol.利用Hess定律计算出2-吡嗪羧酸银的标准摩尔生成焓为:?(243.659±1.298)kJ/mol.利用紫外-可见光谱仪对反应物和产物溶解所得溶液分别进行测量,从而证实了所设计热化学循环的可靠性.     

单原子粒子体系标准摩尔熵和标准摩尔焓的计算

根据统计热力学原理,对单原子粒子体系(固体化合物中阳离子体系和气态阳离子体系)的标准摩尔熵和标准摩尔焓的计算公式进行理论推导,并根据文献中的实验数据进行计算机拟合,得到定量数学模型。通过模型检验,计算值与实验值非常吻合,说明此模型很好地揭示了影响单原子体系标准摩尔熵和标准摩尔焓的微观本质因素。     

水合烟酸钡的合成、±结构表征和热化学性质

选择烟酸和氢氧化钡作为反应物, 利用室温固相合成方法, 借助于球磨技术, 合成了一种新的化合物——水合烟酸钡. 利用化学分析、元素分析、FTIR和X射线粉末衍射等方法确定了它的组成和结构为Ba(Nic)2·3H2O(s). 利用精密自动绝热热量计直接测定了此化合物在78-400 K温区的摩尔热容. 在热容曲线上出现了一个明显的吸热峰, 通过对热容曲线的解析, 得到了相变过程的峰温、相变焓和相变熵分别为(327.097±1.082) K、(16.793±0.084) kJ·mol-1和(51.340±0.164) J·K-1·mol-1. 将该温区的摩尔热容实验值用最小二乘法拟合得到摩尔热容(Cp,m)对温度(T)的多项式方程, 并且在此基础上计算出了它的舒平热容值和各种热力学函数值. 另外, 依据Hess定律, 通过设计合理的热化学循环, 选择体积为100 mL、浓度为0.5 mol·L-1的盐酸作为量热溶剂, 利用等温环境溶解-反应热量计分别测量固相反应的反应物和产物在所选溶剂中的溶解焓, 利用溶解焓确定固相反应的反应焓为⊿rH0m=-(84.12±0.38) kJ·mol-1. 最后, 利用固相反应的反应焓和其它反应物和产物已知的热力学数据计算出水合烟酸钡的标准摩尔生成焓为⊿fH0m[Ba(Nic)2·3H2O(s)]=-(2115.13±1.90) kJ·mol-1.     

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.     

Apparent Molar Heat Capacities and Apparent Molar Volumes of Aqueous Nicotinamide at Different Temperatures

Specific heat capacities and apparent molar heat capacities of aqueous nicotinamide have been determined from 25.0 to 55.0°C using microdifferential scanning calorimetry in the molality range of 0.07433 to 1.50124 mol-kg^–1. Densities and apparent molar volumes have also been determined for aqueous nicotinamide from 10.30 to 34.98°C using a digital densimeter in the molality range 0.07804–2.02435 mol-kg^–1. The results of these measurements have been used to calculate the following partial molar quantities and temperature derivatives for aqueous nicotinamide as a function of temperature: C _p,2,m ^o, (C _p,2,m ^o/T)_p, (²C_p,2,m ^o/T ²)_p, V _2,m ^o, ( V _2,m ^o/T)_p, and (² V _2,m ²/T ²)_p. The results are discussed in terms of the changes in the packing of nicotinamide molecules in the crystal, interactions in the aqueous form, and its structure-promoting ability with rise in temperature.     

Specific thermal and thermodynamic properties of the tellurites Fe2(TeO3)3, Fe2TeO5 and Fe2Te4O11

The temperature dependence of the molar heat capacities of the tellurites Fe₂(TeO₃)₃, Fe₂TeO₅ and Fe₂Te₄O₁₁ were determined. By statistical manipulation of the values obtained, the parameters in the equations for the corresponding compounds showing this dependence were determined using the least-squares method. These equations together with the standard molar entropies were used to determine the thermodynamic functions Δ₀^T S _m⁰, Δ_T^T,H _m⁰ and (Φ_m⁰ + Δ₀^T’ H _m⁰ / T) for T’=298.15 K.     

Standard Molar Volumes and Heat Capacities of Aqueous Solutions of Trifluoromethanesulfonic Acid at Temperatures up to 573 K and Pressures to 30 MPa

Densities and heat capacities of dilute aqueous solutions (0.025 to 0.4 mol⋅kg⁻¹) of trifluoromethanesulfonic acid (triflic acid) were measured with original high-temperature, high-pressure instruments at temperatures and pressures up to 574 K and 31 MPa, respectively. Standard molar volumes and standard molar heat capacities were obtained via extrapolation of the apparent molar properties to infinite dilution. The evolution of these standard derivative properties of triflic acid with temperature and pressure is qualitatively compared with that of other acids of different strengths.     

Thermodynamic properties of the ethylammonium nitrate + water system: Partial molar volumes,heat capacities,and expansivities

Partial molar volumes at 15, 25, and 45°C and partial molar heat capacities and expansivities at 25°C for ethylammonium nitrate + water mixtures are reported. The results are compared with those for other aqueous cosolvents, particularly hydrazine and ammonium nitrate.     

多氟代、多氯代和多溴代二苯并对二噁英化合物的一些性质的比较研究

采用密度泛函理论(DFT)方法, 在B3LYP/6-311G**和B3LYP/6-31G*两种水平上, 对76种多氟代二苯并对二噁英系列化合物(PFDDs)进行了几何构型的全优化, 并计算了各分子在298.15 K, 1.013×10⁵ Pa的标准状态下的热力学参数. 基组从6-31G*增大到6-311G**没有显著改变标准生成热(Δ_fH^?)、标准生成自由能(Δ_fG^?)和标准熵(S^?)数值. 根据B3LYP/6-311G**水平计算得到的Δ_fG^?的相对大小, 求得PFDDs同数目取代氟原子的各异构体的相对稳定性的顺序. 采用基团贡献法计算了多溴代二苯并对二噁英(PBDDs)、多氯代二苯并对二噁英(PCDDs)和PFDDs的辛醇-水分配系数(lg K_ow). 并将PFDDs的Δ_fH^?, Δ_fG^?, S^?和lg K_ow的计算结果与PBDDs和PCDDs的相关数值进行了比较. 同时, 计算了PFDDs各组异构体化合物的生成反应相对速率常数, 采用统计热力学程序计算了这些化合物在200至1800 K的恒压摩尔热容(C_p,m), 并用最小二乘法求得C_p,m与温度之间的相关方程, 发现C_p,m与T, T^－1和T^－2之间有着很好的相关性.     

Measurements of the Molar Heat Capacities and Excess Molar Heat Capacities for Acetonitrile + Diethylamine or sec-Butylamine Mixtures at Various Temperatures and Atmospheric Pressure

As a continuation of our studies of the excess functions of binary systems containing acetonitrile (1−x)–amines (x) mixtures, the molar heat capacity, Cp, and excess molar heat capacity, Cp ^E, of acetonitrile + diethylamine or sec-butylamine mixtures have been determined as a function of composition at 288.15, 293.15, 298.15 and 303.15 K at atmospheric pressure using a modified 1455 PARR solution calorimeter. The excess heat capacity data are positive for both systems over the whole composition range. The experimental data on the excess molar heat capacity are discussed in terms of the influence of the magnitude of the experimental excess molar enthalpy, H ^E, over the curve shaped for the experimental Cp ^E data, molecular interactions in the mixtures, isomeric effect of the amines and modeling of Cp ^E data.     

Heat capacities of tetraphenyl phosphonium chloride in methanol; ethanol; acetonitrile and water

Measurement of heat capacities Cp at 308.65, 311.65 and 314.65 K have been made for solutions of tetraphenyl phosphonium chloride (TPPC) with methanol, ethanol, acetonitrile and water for dilute solutions (up to 0.1 M) by means of a microcalorimeter (Setaram C-80, model from France). The experimental values of heat capacity for the various solutions have been used to calculate the values of partial molar heat capacities Cp_2,m of the salt in different solutions. The results are studied in relation to the special features of solvations in solutions of the TPPC.     

Prediction of Heat of Mixing from Internal Pressure Data

Abstract

Excess enthalpies (H^E _m) and excess heat capacities (C^E _p) of three binary liquid mixtures comprising dimethylformamide, acetonitrile and benzene have been evaluated from internal pressure data obtained from three different approaches. The results obtained have been compared with the experimental H^E _m and C^E _p values determined by Miyanaga et al. [1]. H^E _m values evaluated through density, viscosity and ultrasonic velocity data [2] show anomalous behaviour. A critical review has been given.     

Apparent molar volumes and heat capacities of aqueous solutions of 6,6,9-trimethyladenine and 6,6-dimethyladenine at 25°C, 35°C, and 45°C

Experimental data for aqueous solutions of 6,6,9-trimethyladenine at concentrations from 0.006 to 0.020 molal is provided from differential scanning adiabatic calorimetry, batch calorimetry, and densimetry. The data show nonlinear variations of apparent molar volumes and heat capacities with temperature and concentration. The properties of aqueous solutions of 6,6-dimethyladenine investigated over a similar range of concentration present similar behavior as those of other purine derivatives.