Visible spectrum of dinitrogen trioxide in aqueous solution

Abstract

The visible absorption spectrum of N₂O₃ has been measured by stopped-flow mixing of solutions of NaNO₂ and HNO₃. It has a maximum at 630 nm, ε= 29.3 dm³ mol^–1 cm^–1. The spectrum is similar to that reported for solutions of N₂O₃ in anhydrous organic solvents at low temperatures. Comparison with the blue species observed for solutions of NaNO₂ in moderately concentrated HClO₄ and HNO₃ shows that although the spectra are very similar there must be an additional species present in these very acidic media, possibly N₂O₃H⁺.