Reactions of hydrogen atoms in 6 mol dm–3 sulphuric acid. Part 1.—Temperature dependence of activation- and of diffusion-controlled reactions

Abstract

The reactions of hydrogen atoms in 6 mol dm^–3 H₂SO₄ have been studied over the temperature range 190–280 K, using a pulse-radiolysis technique. The reactions with Mn²⁺ and with propan-2-ol show Arrhenius behaviour, with rate parameters: A=(1.8 ± 0.4)× 10¹² dm³ mol^–1 s^–1, E= 20 ± 2 kJ mol^–1(H + Mn²⁺); A=(1.0 ± 0.3)× 10¹¹ dm³ mol^–1 s^–1, E= 16 ± 2 kJ mol^–1(H + propan-2-ol). The data for the reaction with Ag⁺ respond more satisfactorily to the equation k=A exp{–B/(T—T₀)}, with A=(3.6 ± 0.7)× 10¹² dm³ mol^–1 s^–1, B= 660 ± 100 K, for T₀= 139 K. The reaction between Ag⁰ and Ag⁺ also shows this non-Arrhenius behaviour, with A=(1.2 ± 0.2)× 10¹² dm³ mol^–1 s^–1, B= 670 ± 50 K, T₀= 139 ± 5 K.