Charge exchange reactions of H3O+ with metals in flames

Abstract

Charge exchange reactions of the H₃O⁺ ion with metals have been investigated in the burned gases of atmospheric pressure flames of H₂+O₂+N₂. A quadrupole mass spectrometer was used to determine concentrations of ions in these flames, which cover a temperature range of 1815–2445 K. The following metals were used: Cs, Rb, K, Na, Li, Tl, Cr, Pb, Mn, Cu, Fe, and Cd. The reaction for charge exchange of H₃O⁺ with the alkali metals and Tl is with atoms of the metal M in M+H₃O⁺→M⁺+H₂O+H. For the remaining metals, apart from Cd with which charge transfer does not take place, two reactions MO+H₃O⁺→ MOH⁺+H₂O M+H₃O⁺→MOH⁺+H₂ occur with MOH⁺+H⇌M⁺+H₂O rapid and balanced. The derived rate constants are large, being in the range 0.5–50 × 10^–9 ions ml^–1 s^–1, and have slight negative temperature coefficients.