Homogeneous Isotope Exchange Reactions: Part 3—H2S+D2

Abstract

The kinetics of the early stages of the exchange reaction in H2S + D2 mixtures [H2S, 0.55–9.34 Torr (1 Torr = 133 N m–2); D2, 0.55–6.39 Torr] have been studied in a static system at 808–937 K. The effects of excess argon and surface to volume (s/v) ratio were studied. The initial rate is independent of s/v and in the absence of Ar is described by d[HDS]/dt=[fraction three-over-two]k[H2S][D2]½, where log10([fraction three-over-two]k/dm[fraction three-over-two] mol–½ s–1)= 12.10 ± 0.25–(11 860 ± 220)†/(T/K). The results are in agreement with a homogeneous radical chain mechanism, initiated and terminated heterogeneously. The rate constants for H + H2S [graphic omitted] HS˙+ H2, HS˙+ D2 [graphic omitted] HDS + D, deduced are log10(k3/dm3 mol–1 s–1)= 10.44 ± 0.25–(330 ± 220)/(T/K), log10(k6/dm3 mol–1 S–1)= 10.13 ± 0.25–(3530 ± 220)/(T/K).