1. The problem statement, all variables and given/known data There was a statement in a question which said: "The order of an elementary chemical reaction step can be determined by examining its stoichiometry. " And it was given correct. 2. Relevant equations 3. The attempt at a solution But shouldn't it be wrong? Order of a reaction is found experimentally and nothing else can determine it. So how can we simply see the stoichiometry of a reaction and say " yeah... it has this and this order". Does here "elementary chemical reaction step" make any change to the thing that I am saying?