A micro-oxygen-boinb calorimeter with a bomb of 4.8 cm3 internal volume was constructed in our laboratory. About 10 mg of sample was needed for each combustion experiment.The energy equivalent of this calorimeter was ...A micro-oxygen-boinb calorimeter with a bomb of 4.8 cm3 internal volume was constructed in our laboratory. About 10 mg of sample was needed for each combustion experiment.The energy equivalent of this calorimeter was determmed with electric energy. The standard diviation of mean from 5 measurements was 0.02 %.The enthalpies of combustion of pure C60 and C70 were determined, kJ. mol-1,kJ·mol. The enthalpies of formation of the two compounds were derived. Using the Laidlertype bond parameters for aromatic hydrocarbons, the estimated strain energies in C60 and C70 molecules were close each other and close to the estimated value from the model compound, corannulene.展开更多
By using a micro\|bomb calorimeter, the standard enthalpies of combustion of C 60 and C 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that...By using a micro\|bomb calorimeter, the standard enthalpies of combustion of C 60 and C 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion of C 60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C 60 and C 70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close.展开更多
An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic appro...An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.展开更多
文摘A micro-oxygen-boinb calorimeter with a bomb of 4.8 cm3 internal volume was constructed in our laboratory. About 10 mg of sample was needed for each combustion experiment.The energy equivalent of this calorimeter was determmed with electric energy. The standard diviation of mean from 5 measurements was 0.02 %.The enthalpies of combustion of pure C60 and C70 were determined, kJ. mol-1,kJ·mol. The enthalpies of formation of the two compounds were derived. Using the Laidlertype bond parameters for aromatic hydrocarbons, the estimated strain energies in C60 and C70 molecules were close each other and close to the estimated value from the model compound, corannulene.
文摘By using a micro\|bomb calorimeter, the standard enthalpies of combustion of C 60 and C 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion of C 60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C 60 and C 70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close.
文摘An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.
