Homogeneous isotope exchange reactions

The kinetics of the early stages of the exchange reaction in H2S + D2 mixtures ) 7H2S, 0.55 to 9.34 Torr (1 Torr =133 N m-2); D2, 0.55 to 6.39 Torr{ have been studied in a static system at 808 to 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 d7HDS{/dt = sub(3/2)k7H2S{7D2{sup(1/2) where log10(sub(3/2)k/dmsup(3/2)molsup(-1/2)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 constant for H + H2S → HS. + H2 deduced is log10(k3/dm3mol-1s-1) = 10.44 +- 0.25 -(330 +- 220)/(T/K); and the rate constant for HS. + D2 → HDS + D deduced is log10(k6/dm3mol-1s-1) = 10.13 +- 0.25 -(3530 +- 220)/(T/K). (author). )]