Redox chemistry of hyponitrous acid: Part IV- Stoichiometry, kinetics and mechanism of oxidation by cerium(IV) in acid sulphate solutions, and determination of hyponitrous acid in acid perchlorate solutions

Abstract

In acid sulphate solutions one mole of hyponitrous acid (H₂N₂O₂) reacts with one mole of cerium(IV), and the products are nitrate, N₂O and N₂. The mechanism involves oxidation of hyponitrous acid to an intermediate (probably H₂N₂O₃) which decomposes to yield N₂O and an isomer of HNO₂. The latter reacts with H₂N₂O₂ to yield N₂ and HNO₃. Active oxidant and the substrate species in acid sulphate solutions are found to be CeSO and HN₂O respectively. A rate law compatible with the kinetic results has been derived. In acid perchlorate solutions the reaction is rapid. An indirect titration method of estimating H₂N₂O₂ in about 1.0 mol dm^-3 HClO₄ in the presence of Ce(IV) is described.