溶液反应机理与动力学-2：影响因素与动力学方程的一般形式

对引起溶液反应与气相反应速率差异的因素进行了分析。指出大量溶剂分子的存在,并不会导致反应物分子之间的碰撞频率大幅度降低。除影响反应物活度和起催化作用之外,溶剂化和微观粘度是影响溶液反应速率的主要因素。微观粘度的影响可正可负,可能存在"负粘度"效应。基于简单碰撞理论和过渡态理论,给出了溶液反应速率公式的一般形式,可以综合活化能和微观粘度的影响。该方法可以比较合理地解释一些实验现象。

Kinetics and Mechanism of Solution Reaction-2: Influential Factors and General Form of Kinetic Equation

The influential factors for the rate of reactions occurring in solution which is different from those occurring in gaseous phase are discussed. The perception that the presence of solvent molecules will cause a significant decrease in the collision frequency between reactant molecules is proven incorrect. Except for the changes in activity of reactants and the catalysis due to the presence of solvent, solvent effect and micro-viscosity are found to be the two main factors affecting the rate of the solution reactions. The micro-viscosity is either of positive value due to the interaction between reactants and solvent molecules or of negative value due to the small molar mass of solvent which moves with higher speed. Based on the simple collision theory and transition state theory, a general kinetic equation correlating the change in reaction rate to the changein activation energy and micro-viscosity is proposed. Based on this equation, more satisfactory explanations to the experimental facts can be given.