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 .     

配合物Zn(Phe)(NO3)2·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(Phe)(NO3)2·H2O(s) (Phe:苯丙氨酸)在78-370 K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=(324.27±0.37) K. 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100 mL浓度为2 mol·L-1 的盐酸作为量热溶剂, 利用等温环境溶解-反应热量计分别测定混合物{ZnSO4·7H2O(s)+2NaNO3(s)+L-Phe(s)}和{Zn(Phe)(NO3)2·H2O(s)+Na2SO4(s)}的溶解焓为, ⊿dH0m,1 =(69.42±0.05) kJ·mol-1, ⊿dH0 m,2 =(48.14±0.04) kJ·mol-1, 进而计算出该配合物的标准摩尔生成焓为, ⊿fH0m =-(1363.10±3.52) kJ·mol-1. 另外, 利用紫外-可见(UV-Vis)光谱和折光指数(refractiveindex)的测量结果检验了所设计的热化学循环的可靠性.     

烟酸钠Na(C6H4NO2)(s)的低温热容和热化学

选择分析纯烟酸和无水醋酸钠作为反应物, 用室温固相合成方法合成了无水烟酸钠. 利用FTIR和X射线粉末衍射等方法进行了表征, 利用化学分析和元素分析确定其组成为Na(C6H4NO2). 用精密自动绝热热量计测量其在78~400 K温度区间的低温热容. 研究结果表明, 该化合物在此温度区间无热异常现象发生. 用最小二乘法将实验摩尔热容对温度进行拟合, 得到热容随温度变化的多项式方程. 用此方程进行数值积分, 得到在此温度区间每隔5 K的舒平热容值和相对于298.15 K时的热力学函数值. 在此基础上, 通过设计合理的热化学循环, 选用1 mol/L NaOH溶液作为量热溶剂, 利用等温环境溶解-反应热量计分别测得固相反应的反应物和产物在所选溶剂中的溶解焓, 得到固相反应的反应焓. 最后, 计算出无水烟酸钠的标准摩尔生成焓为: ΔfHm0[Na(C6H4NO2), s]=-(548.96±1.11) kJ/mol.     

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.     

L-丙氨酸和L-组氨酸与铜离子混配合物的热化学

合成了一种新的氨基酸与铜 (Ⅱ )混配型配合物 ,并用具有恒定温度环境反应热量计 ,测定了配合物和反应物在 2 98 2K时 2mol·L-1HCl溶液中的溶解焓 ,由设计的热化学循环得出了配合反应焓变ΔrHm =1 45 92kJ·mol-1,根据热力学原理计算出该配合物的标准摩尔生成焓ΔfHm ,[Cu(Ala·His) ]·4H2 O =-2 0 0 6 5 8kJ·mol-1,为进一步研究这类物质提供了热化学基础参数。     

氯化钆与L-酪氨酸和甘氨酸三元固态配合物的热化学及热分解动力学研究

合成表征了氯化钆与L 酪氨酸和甘氨酸形成的三元固态配合物Gd(Tyr) (Gly) 3 Cl3 ·3H2 O .用具有恒温环境的溶解 -反应热量计 ,测定了配位反应GdCl3 ·6H2 O (s) +Tyr (s) +3Gly (s) =Gd(Tyr) (Gly) 3 Cl3 ·3H2 O (s) +3H2 O (l)在 2 98.15K时的反应焓为 ( 9.45 1± 0 .468)kJ·mol-1 .计算得配合物Gd(Tyr) (Gly) 3 Cl3 ·3H2 O (s)在 2 98.15K时的标准摩尔生成焓为ΔfH m =-( 4 2 69.7± 2 .3 )kJ·mol-1 .并用热分析手段对配合物进行了非等温热分解动力学研究 ,推断配合物第二步热分解反应机理为二级化学反应 ,其动力学方程为 :dα/dT =(A/β)exp( -E/RT) ( 1-α) 2 ,求得分解反应的表观活化能为E =2 15 .17kJ·mol-1 ,指前因子为 10 1 8.71 s-1 .     

三氯醋酸钕与8-羟基喹啉配合物的热化学研究

用溶解量热法 ,在自行研制的具有恒定温度环境的新型反应量热计中 ,测定了NdCl3·6H2 O(s)、CCl3COOH(s)和Nd(TCA) 3·3H2 O(s)在1mol/LHCl中的溶解焓。再根据盖斯定律设计了一个热化学循环 ,计算得到了六水合氯化钕与三氯醋酸反应的反应焓ΔrHmθ(2 98.15K) =2 0 1.688kJ/mol,并求出了Nd(TCA) 3·3H2 O(s)的标准生成焓ΔfHmθ[Nd(TCA) 3·3H2 O ,s ,2 98.15K ] =-3 0 5 3 .3kJ/mol。同时测定了Nd(TCA) 3·3H2 O(s) ,C9H7NO(s) ,Nd(TCA) (C9H6 NO) 2 (s)和CCl3COOH(s)在 4mol/LHCl、二甲亚砜和无水乙醇混合溶剂中的溶解焓 ,再根据盖斯定律设计了一个热化学循环 ,计算得到了三氯醋酸钕与 8 羟基喹啉反应的反应焓ΔrHmθ(2 98.15K) =-3 .2 2 6kJ/mol,并求出了Nd(TCA) (C9H6 NO) 2 (s)的标准生成焓ΔfHmθ[Nd(TCA) (C9H6 NO) 2 ,s ,2 98.15K] =-13 5 5 .6kJ/mol。     

298.16 K时Na+, Mg2+//Cl-, SO42-, NO3-, H2O体系中NaCl饱和区域相平衡

采用等温溶解平衡法研究了五元体系Na+, Mg2+//Cl-, SO42-, NO3-, H2O在298.16 K下氯化钠饱和平衡体系的溶解度, 获得了相应的投影干盐图、氯图和水图. 研究结果表明, 在298.16 K下氯化钠饱和时, 该五元体系投影干盐图由8个二盐共饱和的双变面、13条三盐共饱的单变线和6个四盐共饱的零变点构成, 存在两种复盐, 8个二盐共饱双变面分别对应于NaCl+NaNO3, NaCl+Na2SO4, NaCl+MgCl2·6H2O, NaCl+MgSO4·Na2SO4·4H2O, NaCl+Mg(NO3)2·6H2O, NaCl+NaNO3·Na2SO4·2H2O, NaCl+MgSO4·7H2O 和NaCl+MgSO4·(1—6)H2O. 讨论了该相图在新疆硝酸盐矿开发利用过程中的应用.     

过渡金属二取代三元杂多酸盐的制备和表征

在水中由Na2 WO4 ·2H2 O ,Na2 MoO4 ·2H2 O和KH2 PO4 ·2H2 O反应生成具有半Dawson结构的钨钼混配杂多阴离子Na9PW6Mo3O34 ·1 0H2 O。以阴离子和过渡金属硝酸盐为原料在水溶液中合成了一系列过渡金属二取代的具有Keggin结构的杂多酸四丁基铵盐 [TBA]4 Hn[PW7Mo3M2 O38(H2 O) 2 ]·C3H6O(n =1 ,M =Fe3+;n =3,M =Mn2 +,Co2 +,Ni2 +,Cu2 +) ,用元素分析和波谱进行了表征。     

Tb甘氨酸配合物的热化学研究

本文合成了配合物Tb(Gly)2Cl3·3H2O,用高精度全自动绝热量热仪在81～378 K温区测定了热容,发现在186.054 K和 244.063 K分别存在固-固相变。对配合物进行TG-DTG分析,推测了可能的热分解机理。通过设计适当的Hess热化学循环,利用溶解反应量热计测定了该配合物在298.15 K的标准摩尔生成焓为 -3109.5±3.1 kJ×mol-1。     

Thermochemistry on the Complex of Erbium Perchlorate with L-α-Glutamic Acid [Er2（L-Glu）2（H2O）6]（ClO4）4·6H2O（s）

A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）, was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with relevant literatures, its chemical composition and structure were established. The mechanism of thermal decomposition of the complex was deduced on the basis of the TG/DTG analysis. Low-temperature heat capacities were measured by a precision automated adiabatic calorimeter from 78 to 318 K. An endothermic peak in the heat capacity curve was observed over the temperature region of 290-318 K, which was ascribed to a solid-to-solid phase transition. The temperature Ttrans, the enthalpy △transHm and the entropy △transSm of the phase transition for the compound were determined to be： （308.73±0.45） K, （10.49±0.05） kJ·mol^-1 and （33.9±0.2） J·K^-1·mol^-1. Polynomial equation of heat capacities as a function of the temperature in the region of 78-290 K was fitted by the least square method. Standard molar enthalpies of dissolution of the mixture [2ErCl3·6H2O（s）＋2L-Glu（s）＋6NaClO4·H2O（s）] and the mixture {[Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）＋6NaCl（s）} in 100 mL of 2 mol·dm^-3 HClO4 as calorimetric solvent, and {2HClO4（1）} in the solution A＇ at T=298.15 K were measured to be, △dHm,1=（31.552±0.026） kJ·mol^-1, △dHm,2 = （41.302±0.034） kJ·mol^-1, and △dHm,3 = （ 14.986 ± 0.064） kJ·mol^-1, respectively. In accordance with Hess law, the standard molar enthalpy of formation of the complex was determined as △fHm-=-（7551.0±2.4） kJ·mol^-1 by using an isoperibol solution-reaction calorimeter and designing a thermochemical cycle.     

Preparation and Thermal Chemical Property of Complexes of Zinc Nitrate with Trytophan

IntroductionZincisanessentialtraceelementtothelife .Manydiseasesarousedfromadeficiencyofzincelementhavere ceivedconsiderableattention .L α Aminoacidsarebasicunitsofproteins .L α Trytophanisoneoftheeightspeciesofaminoacidsindispensableforlife ,whichhastobeab sorbedfromfoodbecauseitcannotbesynthesizedinthehumanbody .InviewofthecomplexesofL α trytophanandessentialelementsasaddictiveswidelyusedinsuchfieldsasfoodstuff,medicineandcosmetic ,1 3theyhaveabroadenprospectforapplications .Briefly ,ab…     

Thermal studies and spectral characterization of the chelate of bis-(η5-cyclopentadienyl titanium(IV) with salicylidene-4-methylaniline

A new chelate (η⁵-C₅H₅)₂Ti(SB)₂, whereSB=O, N donor Schiff base salicylidene-4-methylaniline, was synthesized. The course of thermal degradation of the chelate was studied by thermogravimetric (TG) and differential thermal analysis (DTA) under dynamic conditions of temperature. The order of the thermal decomposition reaction and energy of activation was calculated from TG curve while from DTA curve the change in enthalpy was calculated. Evaluation of the kinetic parameters was performed by Coats-Redfern as well as Piloyan-Novikova methods which gaven=1, ΔH=1.114 kJ·mol^?1, ΔE=27.01 kJ·mol^?1, ΔS=?340.12 kJ·mol^?1·K^?1 andn=1, ΔH=1.114 kJ·mol^?1, ΔE=20.01 kJ·mol^?1, ΔS=?342.60 kJ·mol^?1·K^?1, respectively. The chelate was also characterized on the basis of different spectral studies viz. conductance, molecular weight, IR, UV-visible and¹H NMR, which enabled to propose an octahedral structure to the chelate.     

Dehydration Kinetics of Zinc Phosphate Tetrahydrate α-Zn3（PO4）2·4H2O Nanoparticle

TG-DTG technique and Harcourt-Esson integrated equation were used to study the dehydration process of zinc phosphate tetrahydrate α-Zn3（PO4）2·4H2O nanoparticle and its thermal decomposition kinetics. The results show that there are three stages of dehydration between 300 and 800 K during the thermal decomposition of α-Zn3（PO4）2·4H2O nanoparticle. The first stage is controlled by chemical reaction with an activation energy of 69.48 kJ·mol^-1 and a pre-exponential factor of 1.77×10^6 s^-1. The second is controlled by nucleation and growth with an activation energy of 78.74 kJ·mol^-1 and a pre-exponential factor of 5.86×10^9 s^-1. The third is controlled by nucleation and growth with an activation energy of 141.5 kJ·mol^-1 and a pre-exponential factor of 1.01×10^12 s^-1. The kinetic compensative effects not only exist in Arrhenius equation but also in Harcourt-Esson equation. Activation energy E is dependent on both the decomposition fraction α and temperature T.     

Thermochemical Study on [La(Hsal)2•(tch)]•2H2O [Hsal＝salicylate ( ), tch＝thioprolinate (C4H6NO2S-)]

The product from reaction of lanthanum chloride heptahydrate with salicylic acid and thioproline, [La(Hsal)2•(tch)]•2H2O, was synthesized and characterized by IR, elemental analysis, molar conductance, thermogravimatric analysis and chemistry analysis. The standard molar enthalpies of solution of LaCl3•7H2O (s), [2C7H6O3 (s)], C4H7NO2S (s) and [La(Hsal)2•(tch)]•2H2O (s) in a mixed solvent of absolute ethyl alcohol, dimethyl sulfoxide (DMSO) and 3 mol•L－1 HCl were determined by calorimetry to be [LaCl3•7H2O (s), 298.15 K]＝(－102.36±0.66) kJ•mol－1, [2C7H6O3 (s), 298.15 K]＝(26.65±0.22) kJ•mol－1, [C4H7NO2S (s), 298.15 K]＝(－21.79±0.35) kJ•mol－1 and {[La(Hsal)2•(tch)]•2H2O (s), 298.15 K}＝(－41.10±0.32) kJ•mol－1. The enthalpy change of the reaction LaCl3•7H2O (s)＋2C7H6O3 (s)＋C4H7NO2S (s)＝[La(Hsal)2•(tch)]•2H2O (s)＋3HCl (g)＋5H2O (l) (Eq. 1) was determined to be ＝(41.02±0.85) kJ•mol－1. From date in the literature, through Hess’ law, the standard molar enthalpy of formation of [La(Hsal)2•(tch)]•2H2O (s) was estimated to be {[La(Hsal)2•(tch)]•2H2O (s), 298.15 K}＝(－3017.0±3.7) kJ•mol－1.     

Determination of the Enthalpies of Formation of DyI2 and DyI3 and estimation of the Dy3+/Dy2+ standard aqueous electrode potential

DyI₂ and Dy_3I were synthesized by literature techniques. Their enthalpies of solution were determined and their enthalpies of formation calculated to be Δ_fH°(DyI₂, s, 298 K) = ?(394 ± 16) kJ· mol^?1 and Δ_fH°(DyI₃, s, 298 K) = ?(616 ± 10) kJ· mol^?1. With appropriate literature and estimated enthalpies of solution and standard entropies, the E°(Dy³⁺/Dy²⁺, aq) was calculated to be ?(2.6 ± 0.2) V. A comparison is made of the enthalpies of reduction of DyI₃ to DyI₂ and of DyCl₃ to DyCl₂.     

Standard molar enthalpies of formation of KCdCl3 and K4CdCl6 by high-temperature drop calorimetry

Enthalpies of the synthesis reactions of the two compounds KCdCl₃(cr) and K₄CdCl₆(cr) from KCl(cr) and CdCl₂(cr) have been measured by drop calorimetry of solid samples of KCl, CdCl₂, KCdCl₃, and K₄CdCl₆ into melted mixtures of KCl and CdCl₂. For the two reactions: (1), CdCl₂(cr)+KCl(cr) = KCdCl₃(cr); and (2), CdCl₂(cr)+4KCl(cr) = K₄CdCl₆(cr), the experiments lead to the two standard molar enthalpies of reaction at 298.15 K: Δ₁H_m^o = ?(21.7±1.0) kJ·mol^?1 and Δ₂H_m^o = ?(39.0±3.8) kJ·mol^?1. These values are not in good agreement with those of previous workers.     

对氨基苯甲酸热力学性质的量热和热分析研究

在80～400 K温区,用高精度全自动绝热量热仪测定了对氨基苯甲酸摩尔热容,得到摩尔热容随温度的变化的关系式为：     

Crystal Structure, Phase Transition, and Thermodynamic Properties of Bis-dodecylammonium Tetrachlorozincate (C12H25NH3)2ZnCl4(s)

The crystal structure and composition of (C₁₂H₂₅NH₃)₂ZnCl₄(s) were characterized by chemical and elemental analysis, X‐ray powder diffraction technique and X‐ray crystallography. The lattice energy of the title compound was calculated to be U_POT=888.82 kJ·mol^?1. Low temperature heat capacities of the title compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 403 K. An obvious solid to solid phase transition occurred in the heat capacity curve, and the peak temperature, molar enthalpy and molar entropy of the phase transition of the compound were determined to be T_trs= (364.02±0.03) K, (_trsH_m= (77.567±0.341) kJ·mol^?1, and (_trsS_m= (213.77±1.17) J·K^?1·mol^?1, respectively. Experimental molar heat capacities before and after the phase transition were respectively fitted to two polynomial equations. The smoothed molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at an interval of 5 K.