Question

Consider the decomposition of hydrogen peroxide in the alkaline medium which is catalysed by iodide ions.
This reaction takes place in two steps as given below
step-1 `H_(2)O_(2) + I^(-1) to H_(2)O + IO^(-)(Slow)`
Step II `H_(2)O_(2) + IO^(-) to H_(2)O + I^(-) +O_(2)` (fast)
a) Write the rate law expression and determine the order of reactan w.r.t `H_(2)O_(2)`
b) What is the molecularity of each individual step?

Answer 1

a) Rate law expression:
Rate = `k[H_(2)O_(2)][I^(-)]`
Order of reaction w.r.t `H_(2)O_(2)=1`
b) Molecularities of both step-I and step-II are two.