Acta Chimica Sinica ›› 1998, Vol. 56 ›› Issue (1): 13-20. Previous Articles     Next Articles

Original Articles

特征参量法1: 简单级数反应的热动力学研究法

曾宪诚;张元勤;胡启山;田安民   

  1. 四川大学化学系
  • 出版日期:1998-01-15 发布日期:1998-01-15

Characteristic parameter method I. Thermokinetic research method of simple order reactions

ZENG XIANCHENG;ZHANG YUANQIN;HU QISHAN;TIAN ANMIN   

  • Online:1998-01-15 Published:1998-01-15

A linear-fitting method for measuring the cooling constant of a thermokinetic system has been proposed in this paper. The cooling constants of thermokinetic systems of the reaction of nitroethane with tris (hydroxymethyl) aminomethane in 1mol.L^-^1 KCl aqueous solution and saponification of ethyl butyrate in ω=0.85 aqueous ethanol have been measured with this method at 15, 30, and 45℃, respectively. The results show that the cooling constants measured with this method have good reproducibility and self-adaptability, and are in good agreement with those measured with steady-state peak-height method. Therefore, the linear-fitting method for measuring cooling constants is believed to be correct. The effects of temperature, medium, concentrations of reactants and sample-feeding manner on the cooling constant of a thermokinetic system have also been discussed. The results show that medium and sample-feeding manner have great effects on the cooling constant. Nevertheless, the relative error of the cooling constant is only about 1% when the initial concentrations of reactants vary onefold at the same temperature and in the same solvent to a same reaction. Based on the basic theory of thermokinetics proposed in the literatures, a novel research method of thermokinetics which can be applied to study slow and fast reactions, the characteristic parameter method, has been developed in this paper. The general formulas for calculating kinetic parameter Kn and rate constants kn have been derived. In order to test the validity of this novel method, the saponification of ethyl acetate, ethyl propionate and ethyl benzoate, the formation of hexamethylenetetramine and the polymerization of acrylamide, have been studied. All the experimental results are in good agreement with those in the literatures, and therefore the characteristic parameter method has been proved valid.

Key words: NITRO COMPOUNDS, REACTION KINETICS, REACTION RATE CONSTANT, ETHANE P, ETHYL BUTYRATE

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