Stopped-flow method first-order conditions

Under pseudo first order conditions this reaction could be studied by stopped-flow methods and plots of In(abs) versus time were linear over four to five half lives as shown in Figure 4. This data was analyzed in terms of the following mechanism (Wk = (P(C6Hu)3)2W(CO)3) ... 

Kinetic data were obtained under pseudo-first-order conditions in the presence of a large excess of a-CD The inclusion reactions with S-CD were too fast to measure by the stopped-flow method. The values of the rate constants are summarized in Table 3. The two-step process was observed in the formation of LH 3- aCDx MLH aCDx Figure k shows the plots of the observed rate constants, kg and k, for the fast and the slow processes respectively against the total a-CD concentration, [a-CD ] From the dependence of kg and k- on [a-CD ], two types of reaction Schemes, 3 and can be considered. 

Reaction (1) was followed at 25 C by the stopped-flow method in acetone as solvent and under pseudo first-order conditions with the nucleophile in large excess. The metallopor-phyrin concentration was about 5 x 10 M. The results are given in the Table and a typical kinetic plot in Figure 1. 

L Vov first developed a kinetic model for atomization, based on increasing temperature, such as that found in a rod-type system. Fuller developed a model for atomization under isothermal conditions, applicable to less volatile elements in tube-type systems. Fuller s model assumes first-order kinetics and involves a number of other assumptions, but its usefulness has been demonstrated. For example, it confirms the usefulness of integration when atomization is slow (at relatively low temperatures or when investigating involatile elements), the enhancement of sensitivity available from stopping the flow of purge gas during the atomization cycle, and indicates methods for the control of interferences. 

This method may be viewed as an adaptation of pulsed continuous flow, in which the flow rate through the mixer and observation chamber is varied during the course of one run. Most applications of this method have been from Margerum and co-workers. The method can be used for half-times down to -10 ps, compared to -10 ms for stopped flow. The complexity of the analysis limits the method to first-order reaction conditions. 

The kinetics of the redox reaction between iron(m) and iodide ion have been reinvestigated over a very wide range of reactant conditions using the method of initial rates. Both stopped-flow and conventional spectrophotometry were used, the first-order dependence on the oxidant and second-order on iodide being confirmed. No evidence was found for any intermediate complex and the reaction scheme proposed may be described as... 

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