GAS-CHROMATOGRAPHIC DETERMINATION OF RATE CONSTANTS IN BIMOLECULAR GASEOUS REACTIONS

Rate constants for bimolecular reactions in the gas phase, under diffu sion controlled conditions, can easily be determined by the reversed-f low gas chromatography (RF-GC) technique. The analysis of the diffusio n band by means of a simple PC programme gives directly an apparent, s econd-order rate constant for gaseous reactions. By varying the amount s of the reactants, one can calculate the true order of the reaction a nd the true non-first-order rate constant of gaseous reactions. The ca libration problem of the analytical techniques in non-first-order reac tion kinetics is absent as are other disadvantages connected with carr ier gas flow, peak shape and their instrumental spreading. The method can be used for atmospheric reactions and was applied in the gaseous r eaction systems: SO2 + NO2, SO2 + Br-2, C6H6 + NO2, C6H5CH3 + NO2 and C3H6 + NO2 with various concentrations of reactants in nitrogen. The e ffect of the NO2 concentration on the apparent second-order rate const ant of C2H4 + NO2 at 333.2 K was also studied. Finally, the effect of sun light pre-irradiation of C2H2 + NO2 in nitrogen was investigated.