A student is studying a multi-step reaction that can be represented symbolically as
overall reaction: A(g) + 2 B(g) → C(g) + D(g)
The student is told that the first elementary step is slow and the remaining steps are all much faster.
Use your knowledge of chemical kinetics to analyze how the rate of the overall reaction is governed by the nature of the slow step.
(a) Explain why, when one elementary step in a mechanism is significantly slower than all others, the rate law for the overall reaction depends exclusively on that slow step.
(b) Describe the relationship between the molecularity of an elementary step and the exponents that appear in a differential rate law derived from that step.
(c) The student claims that because the stoichiometric coefficient of B in the overall balanced equation is 2, the rate law must be r=k[A][B]2. Evaluate this claim and justify your reasoning.