Kinetic study of the reaction between ferriin and nitrous acid by a concentration jump–stopped flow technique

Abstract

The kinetics of the reaction between ferriin and nitrous acid have been studied as an extension of the investigation of the 2Fe(phen)²⁺₃+ NO^–₃+ 3H⁺⇌ 2Fe(phen)³⁺₃+ HNO₂+ H₂O reversible reaction. Owing to the dynamic equilibrium which exists in this system, the equilibrium position can be shifted from the right-hand side by dilution, and this allows an investigation of the kinetics of the backward reaction by means of the concentration jump method. If excess nitrite (nitrous acid) was applied a pseudo-first-order condition was reached for the ferriin–nitrous acid reaction owing to the peculiar behaviour of the mechanism of the overall process. The kinetic results were compared to those obtained previously and confirm the two-step mechanism proposed for the forward reaction.