Variable-ionic-strength kinetic experiments

Variable-Ionic-Strength Kinetic Experiments Conclusions... 

Ahbrandi, G., Coppolino, S., D Aliberti, S., Ficarra, P., Micali, N., and Villari, A. (2003), Variable-ionic strength kinetic experiments to study drug stabihty, J. Pharm. Sci., 92, 1730-1733. 

Although the rate of the reaction is the parameter in kinetic studies which provides the link between the experimental investigation and the theoretical interpretation, it is seldom measured directly. In the usual closed or static experimental system, the standard procedure is to follow the change with time of the concentrations of reactants and products in two distinct series of experiments. In the first series, the initial concentrations of the reactants and products are varied with the other reaction variables held constant, the object being to discover the exact relationship between rate and concentration. In the second series, the experiments are repeated at different values of the other reaction variables so that the dependence of the various rate coefficients on temperature, pressure, ionic strength etc., can be found. It is with the methods of examining concentration—time data obtained in closed systems in order to deduce these relationships that we shall be concerned in this chapter. However, before embarking on a description of these... 

The elucidation of a substitution reaction mechanism depends on reliable kinetic and thermodynamic data obtained by measuring changes in the reaction rate as a function of a chemical property (e.g., concentration, pH, ionic strength, solvent polarity) or physical quantity (e.g., temperature). The determination of an empirical rate law, the observation of steric or electronic effects induced by the entering, spectator, or leaving groups, and the estimation of activation parameters from variable-temperature experiments (i.e.. A// and Aj ) contribute to the adjudication of a plausible mechanism for a given reaction. 

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