A novel compound-monohydrated zinc nicotinate was prepared via room temperature solid phase synthesis and ball grinding.FTIR,chemical and elemental analyses and X-ray powder diffraction technique were applied to chara...A novel compound-monohydrated zinc nicotinate was prepared via room temperature solid phase synthesis and ball grinding.FTIR,chemical and elemental analyses and X-ray powder diffraction technique were applied to characterizing the structure and composition of the complex.Low-temperature heat capacities of the solid coordination compound were measured by a precision automated adiabatic calorimeter over a temperature range from 77 to 400 K.A solid-solid phase transition process occurred in a temperature range of 321―342 K inferred according to the heat capacity curve,and the peak temperature,molar enthalpy and entropy of the phase transition of monohydrated zinc nicotinate were determined to be Ttrs=（340.584±0.829） K,ΔtrsHm=（12.682±0.041） kJ/mol and ΔtrsSm=（37.235±0.101） KJ/mol）.The experimental values of the molar heat capacities in the temperature regions of 77―321 K and 342―400 K were,respectively,fitted to two polynomial equations.In addition,the polynomial fitted values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K.展开更多
The construction of an automated adiabatic calorimeter for heat capacity measurement ofsolids in the temperature range of 25- 90K is described in detail. The sample vessel of thecalorimeter has thin radial vanes which...The construction of an automated adiabatic calorimeter for heat capacity measurement ofsolids in the temperature range of 25- 90K is described in detail. The sample vessel of thecalorimeter has thin radial vanes which make no contact with its inner wall and are distrib-uted evenly, thus greatly improving the internal thermal equilibration of the vessel. Theprecision of temperature control for the adiabatic shields and electrical leads of the calori-metric system are heightened to a great extent by using the high precision ACD- 79 modeladiabatic controller specially developed by us for this purpose. Measurements of the heatcapacities of high purity α-Al_2O_3, one of the internationally-accepted standard referencematerials, agree with those of the National Bureau of Standards (NBS), USA within ±0.3%,demonstrating the reliability of this apparatus.展开更多
The solid potassium L-threonate hydrate, K（C4H7O5）·H2O, was synthesized by the reaction of L-threonic acid with aqueous potassium hydrogen carbonate and characterized by means of chemical and elemental analyses...The solid potassium L-threonate hydrate, K（C4H7O5）·H2O, was synthesized by the reaction of L-threonic acid with aqueous potassium hydrogen carbonate and characterized by means of chemical and elemental analyses, IR and TG-DTG. Low-temperature heat capacity of K（C4H7O5）·H2O has been precisely measured with a small sample precise automated adiabatic calorimeter over the temperature range from 78 to 395 K. An obvious process of the dehydration occurred in the temperature region of 364-382 K. The peak temperature of the dehydration of the compound has been observed to be （380.524±0.093） K by means of the heat capacity measurements. The molar enthalpy, △dHm, and molar entropy, △dSm, of the dehydration of K（C4H7O5）·H2O were calculated to be （19.655 ± 0.012） kJ/mol and （51.618 ± 0.051） J/（K·mol） by the analysis of the heat-capacity curve. The experimental molar heat capacities of the solid from 78 to 362 K and from 382 to 395 K have been respectively fitted to two polynomial equations of heat capacities against the reduced temperatures by least square method. The constant-volume energy of combustion of the compound, △cUm, has been determined to be （- 1749.71 ±0.91） kJ·mol^-1 by an RBC-Ⅱ precision rotary-bomb combustion calorimeter at 298.15 K. The standard molar enthalpy of formation of the compound, △fHm , has been calculated to be （- 1292.56± 1.06） kJ·mol^-1 from the combination of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities.展开更多
The heat capacity of 2- chloro- 6- (trichloromethyl)pyridine has heen measured with anadiabatic calorimeter in the range from 13 to 316K. There is no indication of any phasetransition or thermal anomaly in this temper...The heat capacity of 2- chloro- 6- (trichloromethyl)pyridine has heen measured with anadiabatic calorimeter in the range from 13 to 316K. There is no indication of any phasetransition or thermal anomaly in this temperature region for the present compound. Theresults have been compared with those reported in [1] in the overlapping temperaturerange. The experimental heat capacity data have been fitted to a smoothed curve by the aidof the effective frequency distribution method, and the heat capacities below 13K have beenobtained by extrapolating the fitting curve down to 0K. The standard molar thermodynamicfunctions between 0 and 400 K have been derived by combining the present heat capacitymeasurements with the previous ones. The values of C_p^o (T), S^o(T) - S^o(0), [H^o(T) -H^o(0)]/T, and - [G^o(T) - H^o(0)]/T at T = 298.15 K are 189.35, 244.60, 112 .45 and 132.15J·K^(-1)·mol^(-1), respectively.展开更多
基金Supported by the National Natural Science Foundation of China(No.20673050)Key Project of Science Foundation from Shaanxi Educational College of China(No.08KJ017)
文摘A novel compound-monohydrated zinc nicotinate was prepared via room temperature solid phase synthesis and ball grinding.FTIR,chemical and elemental analyses and X-ray powder diffraction technique were applied to characterizing the structure and composition of the complex.Low-temperature heat capacities of the solid coordination compound were measured by a precision automated adiabatic calorimeter over a temperature range from 77 to 400 K.A solid-solid phase transition process occurred in a temperature range of 321―342 K inferred according to the heat capacity curve,and the peak temperature,molar enthalpy and entropy of the phase transition of monohydrated zinc nicotinate were determined to be Ttrs=（340.584±0.829） K,ΔtrsHm=（12.682±0.041） kJ/mol and ΔtrsSm=（37.235±0.101） KJ/mol）.The experimental values of the molar heat capacities in the temperature regions of 77―321 K and 342―400 K were,respectively,fitted to two polynomial equations.In addition,the polynomial fitted values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K.
文摘The construction of an automated adiabatic calorimeter for heat capacity measurement ofsolids in the temperature range of 25- 90K is described in detail. The sample vessel of thecalorimeter has thin radial vanes which make no contact with its inner wall and are distrib-uted evenly, thus greatly improving the internal thermal equilibration of the vessel. Theprecision of temperature control for the adiabatic shields and electrical leads of the calori-metric system are heightened to a great extent by using the high precision ACD- 79 modeladiabatic controller specially developed by us for this purpose. Measurements of the heatcapacities of high purity α-Al_2O_3, one of the internationally-accepted standard referencematerials, agree with those of the National Bureau of Standards (NBS), USA within ±0.3%,demonstrating the reliability of this apparatus.
基金Project supported by the National Natural Science Foundation of China （No. 20171036）, Education Committee of Shannxi Province （Nos. 01JK229, FF02328 and 2004B 10） and Postgraduate Foundation of China.
文摘The solid potassium L-threonate hydrate, K（C4H7O5）·H2O, was synthesized by the reaction of L-threonic acid with aqueous potassium hydrogen carbonate and characterized by means of chemical and elemental analyses, IR and TG-DTG. Low-temperature heat capacity of K（C4H7O5）·H2O has been precisely measured with a small sample precise automated adiabatic calorimeter over the temperature range from 78 to 395 K. An obvious process of the dehydration occurred in the temperature region of 364-382 K. The peak temperature of the dehydration of the compound has been observed to be （380.524±0.093） K by means of the heat capacity measurements. The molar enthalpy, △dHm, and molar entropy, △dSm, of the dehydration of K（C4H7O5）·H2O were calculated to be （19.655 ± 0.012） kJ/mol and （51.618 ± 0.051） J/（K·mol） by the analysis of the heat-capacity curve. The experimental molar heat capacities of the solid from 78 to 362 K and from 382 to 395 K have been respectively fitted to two polynomial equations of heat capacities against the reduced temperatures by least square method. The constant-volume energy of combustion of the compound, △cUm, has been determined to be （- 1749.71 ±0.91） kJ·mol^-1 by an RBC-Ⅱ precision rotary-bomb combustion calorimeter at 298.15 K. The standard molar enthalpy of formation of the compound, △fHm , has been calculated to be （- 1292.56± 1.06） kJ·mol^-1 from the combination of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities.
文摘The heat capacity of 2- chloro- 6- (trichloromethyl)pyridine has heen measured with anadiabatic calorimeter in the range from 13 to 316K. There is no indication of any phasetransition or thermal anomaly in this temperature region for the present compound. Theresults have been compared with those reported in [1] in the overlapping temperaturerange. The experimental heat capacity data have been fitted to a smoothed curve by the aidof the effective frequency distribution method, and the heat capacities below 13K have beenobtained by extrapolating the fitting curve down to 0K. The standard molar thermodynamicfunctions between 0 and 400 K have been derived by combining the present heat capacitymeasurements with the previous ones. The values of C_p^o (T), S^o(T) - S^o(0), [H^o(T) -H^o(0)]/T, and - [G^o(T) - H^o(0)]/T at T = 298.15 K are 189.35, 244.60, 112 .45 and 132.15J·K^(-1)·mol^(-1), respectively.
基金supported by the National Natural Science Foundation of China (20373072)Construct Program of the Key Discipline in Hunan Province,China (Applied Chemistry)~~
