Investigations on the influence of halogen and sulfate ions upon the catalytic activity of silver

Abstract

It is shown in the present work that bromine ions (like chlorine ions) block up the active surface of the silver catalyst, in the decomposition of hydrogen peroxide. This process is connected with a specific adsorption, leading to an increase of the pH value of the medium. Owing to the decomposition of H 2O 2, which grows with the alkalinity of the medium, the curve: activity vs. conc. of Br − passes through a maximum. The experimental data are in good agreement with Eq. (13), deduced for the above cases. Making an allowance for a Langmuir adsorption, the heat of adsorption of Br − on silver has been calculated from the kinetic data as γ Br− a = 5060 cal/mole. Analogous curves have been obtained for the effect of I − and SO 4 2− ions upon the catalytic activity of silver in the decomposition of H 2O 2. The place of the maxima in the curves agrees with the theoretical assumption given.