Kinetics of oxidation of formic acid by silver(II) in aqueous perchloric acid solution

Abstract

The kinetics of oxidation of formic acid by silver(II) in acidic perchlorat emedia (1.00 ⩽[HClO₄]⩽ 4.00M) at 14.0, 22.0, and 30.0 °C have been investigated by means of a stopped-flow spectrophotometric technique. The experimental rate law, at constant [H⁺] and with formic acid in excess, is –d[Ag^II]/dt=k_I⁰[Ag^II][HCO₂H]+k_II⁰[Ag^II]²+[HCO₂H][Ag^I]^–1. The [H⁺] dependence of the terms is explained by taking into account the presence of the hydrolyzed species [Ag(OH)]⁺ and [Ag(OH)]²⁺: the corresponding hydrolysis equilibrium constants have been evaluated. The mechanism of the reaction is discussed in terms of different paths and reacting species. Comparison is made with previous findings concerning formic acid oxidation with other metal ions and oxidations with Ag^II.