Experimental study of a ternaryA+2B→Creaction-diffusion system with a propagating reaction front: Scaling exponents

We study experimentally the $A+2B\to C$ reaction-diffusion process with initially separated reagents in a capillary using an inorganic chemical reaction. We measure and compare with theory the dynamic quantities that characterize the kinetic behavior of the system: the global reaction rate $R\left(t\right),$ the location of the reaction center $x_f\mathrm{}\left(t\right),$ the front’s width $w\left(t\right),$ and the local production rate ${R(x}_f,t).\mathrm{}$ We demonstrate the nonclassical phenomena of reactant segregation and depletion-zone formation for this reaction-diffusion process. The experimental results are in good agreement with theory and simulation and quite different from the exponents for the elementary binary $A+B\to C$ reaction. The time exponents are 0.27 for the width, -0.48 for the global reaction rate, and -0.75 for the local reaction rate, compared to theoretical values of 0.25, -0.5, and -0.75, respectively.