1. The problem statement, all variables and given/known data Reaction: 2A --> C Step 1: A <-> M (fast) Step 2: M + A -> C (slow) What is the observed rate law? 2. Relevant equations Rate = k[A][...] 3. The attempt at a solution The observed rate law seems to be k[A]^2. However, why is it so? Why does the rate depend on the concentration of A squared? I know that the rate of the reaction is determined by the slowest step, and that the steps in the reaction must add up to the overall reaction (it does in this case). What's the "for dummies" explanation for reaction mechanisms?