Determination of rate constants by a double-line flow injection method incorporating a well-stirred tank reactor

Equations have been derived for the concentration-time profiles of reactants and products in a first order reaction obtained on passage of a reactant plug through a single well-stirred tank reactor. When taken together with the equations for physical dispersion of such a reactor under plug flow conditions, an expression for the reaction rate constant was derived which allowed its experimental determination in a relatively simple fashion. The method was tested for reactions between cerium and oxalic acid and between dichromate and ascorbic acid, for which values of the rate constants of around 2 x 10(2) sec(-1) and 5.5 x 10(3) sec(-1) were obtained. Good agreement with other experimentally determined values was obtained. The scope and the limitations of the proposed method are critically discussed with the aid of some model calculations. The range of values for which the method might be suitable is approximately 10(-3)-10(-1) sec(-1). An equation analogous to a peak-width equation was derived as a further development of this approach. Good agreement with the previously determined values were obtained for both systems. The extension of the method to reactions other than first order is discussed.