Participation of hydrogen peroxide in halogen activation in the low stratosphere
Abstract:Measurements of hydrogen peroxide conversion into Caro's acid in sulphuric acid at T ≈ 298 K and H2SO4 content 78/95 wt% were performed to monitor the equilibriums: H2O2 + H3O+ ↔ H3O2+ + H2O and H2O2 + HSO4- ↔ HSO5- + H2O yielded K(298) = 8 × 10-4 and K(298) = 1.2 × 10-2, respectively. The physical solubility of H2O2 as well as that including H3O2+ and HSO5- has been estimated. The calculation of the Henry's law coefficient (T = 298) of H2O2 shows the typical salting-out effect, while for the case of H3O2(aq)+ and HSO5(aq)- this coefficient exhibits a sharp rising with H2SO4 content, starting from almost 50 wt%. An increase in the oxidative power of H2O2, H3O2(aq)+ and HSO5(aq)- is observed, as H2SO4 concentration increases. In addition, the kinetics of the liquid-phase reactions involving these reagents are analysed on the basis of a correlation between the rate constants and the thermodynamic data. Finally, the occurrence of sulphate aerosol reactions involving the components that affect halogen activation in the low stratosphere is discussed.
Document Type: Research Article
Affiliations: Institute of Energy Problems of Chemical Physics, Moscow, Russia
Publication date: March 1, 2010