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Crystal structure and thermochemical properties of bis(1-octylammonium) tetrachlorochromate phase change materials
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A new crystalline complex(C8 H17 NH3) 2 CdCl 4(s)(abbreviated as C8Cd(s)) is synthesized by liquid phase reaction.The crystal structure and composition of the complex are determined by single crystal X-ray diffraction,chemical analysis,and elementary analysis.It is triclinic,the space group is P-1 and Z = 2.The lattice potential energy of the title complex is calculated to be U POT(C 8 Cd(s))=978.83 kJ·mol-1 from crystallographic data.Low-temperature heat capacities of the complex are measured by using a precision automatic adiabatic calorimeter over a temperature range from 78 K to 384 K.The temperature,molar enthalpy,and entropy of the phase transition for the complex are determined to be 307.3±0.15 K,10.15±0.23 kJ·mol-1,and 33.05±0.78 J·K-1 ·mol-1 respectively for the endothermic peak.Two polynomial equations of the heat capacities each as a function of temperature are fitted by using the leastsquare method.Smoothed heat capacity and thermodynamic functions of the complex are calculated based on the fitted polynomials. 相似文献
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合成了乙二胺盐酸盐, 并表征了其晶体结构. 测定了其在78~370 K温度区间的低温热容, 通过最小二乘法拟合得到热容对温度的多项式方程. 设计了合理的热化学循环, 测定了所设计反应的反应物和产物的溶解焓, 得到反应焓. 利用Hess定律计算出乙二胺盐酸盐的标准摩尔生成焓为-(540.74±1.33) kJ/mol. 利用紫外-可见光谱和折光指数的结果检验了所设计热化学循环的可靠性. 相似文献
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熵—证券投资组合风险的一种新的度量方法 总被引:16,自引:0,他引:16
本文在研究马科维茨 ( Markowitz)证券投资组合模型的基础上 ,分析了该模型用方差度量风险的缺陷 ,进而提出用熵作为风险的度量方法 ,改进马科维茨 ( Markowitz)证券投资组合模型 ,并建立新的证券投资组合优化模型 相似文献
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Lattice potential energy and standard molar enthalpy in the formation of 1-dodecylamine hydrobromide (1-C12H25NH3 ·Br)(s)
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This paper reports that 1-dodecylamine hydrobromide (1--C12H25NH3·Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1--C12H25NH3·Br and the ionic volume and radius of the 1--C12H25NH3+ cation are obtained from the crystallographic data and other auxiliary thermodynamic data. The constant-volume energy of combustion of 1--C12H25NH3·Br(s) is measured to be Δc Umo(1--C12H25NH3·Br, s) =--(7369.03±3.28) kJ·mol-1 by means of an RBC-II precision rotating-bomb combustion calorimeter at T=(298.15±0.001) K. The standard molar enthalpy of combustion of the compound is derived to be Δc Hmo(1--C12H25NH3·Br, s)=--(7384.52±3.28) kJ·mol - 1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be Δf Hmo(1--C12H25NH3·Br, s)=--(1317.86±3.67) kJ·mol-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle. 相似文献
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无水苯甲酸锂的合成、结构表征及热化学研究 总被引:1,自引:1,他引:0
用分析纯苯甲酸和一水氢氧化锂作为反应物, 采用水热合成法制得苯甲酸锂. 利用X射线粉末衍射、FTIR、元素分析及化学分析等方法对样品进行组成和结构表征. 采用精密自动绝热热量计测量了其在80~400 K范围内的摩尔热容, 利用最小二乘法将此温区热容实验值对折合温度进行拟合, 得到热容随温度变化的多项式方程. 通过设计合理的热化学循环, 选用0.1 mol/L HCl溶液作为量热溶剂, 利用等温环境溶解-反应热量计分别测定合成反应的反应物和产物在所选溶剂中的溶解焓, 得到反应焓ΔrHm0=-(9.75±0.27) kJ/mol. 利用Hess定律计算出苯甲酸锂的标准摩尔生成焓ΔfHm0(C6H5COOLi, s)=-(307.82±0.57) kJ/mol. 相似文献
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无水烟酸锂的合成、结构表征及热化学性质 总被引:1,自引:0,他引:1
选择分析纯烟酸和一水氢氧化锂为反应物, 利用水热合成方法合成了无水烟酸锂. 利用FTIR和X射线粉末衍射等方法表征了它的结构. 用精密自动绝热热量计测定了它在78~400 K温区的低温热容, 将该温区的摩尔热容实验值用最小二乘法拟合, 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, 得到温区内每隔5 K的舒平热容值和相对于298.15 K时的各种热力学函数值. 在此基础上, 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该反应的反应物和生成物在所选溶剂中的溶解焓, 从而得到此反应的反应焓为: =-(20.21±0.41) kJ8226; mol-1. 最后, 依据Hess定律计算出无水烟酸锂的标准摩尔生成焓为: [Li(C6H4NO2), s]=-(278.29±1.01) kJ8226;mol-1. 相似文献
8.
Crystal structure and thermochemical properties of phase change materials bis(1-octylammonium) tetrachlorochromate
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A new crystalline complex (C8H17NH3)2CdCl4(s) (abbreviated as C8Cd(s)) is synthesized by liquid phase reaction. The crystal structure and composition of the complex are determined by single crystal X-ray diffraction, chemical analysis, and elementary analysis. It is triclinic, the space group is P-1 and Z = 2. The lattice potential energy of the title complex is calculated to be UPOT (C8Cd(s))=978.83 kJ·mol-1 from crystallographic data. Low-temperature heat capacities of the complex are measured by a precision automatic adiabatic calorimeter over a temperature range from 78 K to 384 K. The temperature, molar enthalpy, and entropy of the phase transition for the complex are determined to be 307.3± 0.15 K, 10.15± 0.23 kJ·mol-1, and 33.05± 0.78 J·K-1·mol-1 respectively for the endothermic peak. Two polynomial equations of the heat capacities each as a function of temperature are fitted by the least-square method. Smoothed heat capacity and thermodynamic functions of the complex are calculated based on the fitted polynomials. 相似文献
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合成了四氯合锌酸正九烷铵复合物(C9H19NH3)2ZnCl4(s) (C9Zn(s)), 并使用X射线单晶衍射、化学分析以及元素分析确定了其晶体结构和化学组成. 利用其晶体学数据推导了C9Zn(s)的晶格能UPOT=952.94 kJ·mol-1. 在298.15 K下, 利用恒温环境溶解-反应热量计测定了C9Zn(s)在不同质量摩尔浓度下的摩尔溶解焓. 在Pitzer电解质溶液理论基础上确定了C9Zn(s)的无限稀释摩尔溶解焓ΔsΗm∞=20.09 kJ·mol-1, 以及Pitzer焓参数组合(4βC9H19NH3,Cl(0)L+2βZn,Cl(0)L+θC9H19NH3,ZnL)和(2βC9H19NH3,Cl(1)L+βZn,Cl(1)L)的值. 相似文献
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