The decomposition of H2O2 catalysed by I^- has rate = k[H2O2][I^-] and proceeds via a slow first step. What is the molecularity of the rate determining step?

1. The slow step is $H_2O_2 + I^- \rightarrow H_2O + IO^-$. 2. Two species collide simultaneously in this step. 3. So its molecularity is two, i.e. bimolecular. 4. This matches the observed overall second order rate law. _Source: syllabus Chemistry Ch 3 "Chemical Kinetics", p.9_