Kinetics of the oxidation of nitrous acid by tetrachloroaurate(III) inHCl

Summary The kinetics of the reaction between nitrous acid and gold(III) in an HCl medium was studied. The reaction was first order with respect to [Au^III] and [HNO₂]·H⁺ and Cl^- ions inhibit the rate and alkali metal ions have specific effects on the rate. The reaction appears to involve different gold(III) species, viz. AuCl_inf4^sup–, AuCl₃(OH₂) and AuCl₃(OH)^–, which undergo a two-equivalent reduction to gold(I) leading to the formation of NO_inf2^sup+which under-goes rapid hydrolysis to give nitric acid.