Final answer:
The rate law for an elementary reaction is determined by the stoichiometry of the reaction and takes into account the concentration of the reactants and the rate constant.
Step-by-step explanation:
The rate law for an elementary reaction can be determined by considering the stoichiometry of the reaction. For a unimolecular reaction, the rate law is proportional to the concentration of the reactant. For a bimolecular reaction, the rate law is proportional to the product of the concentrations of the reactants. In both cases, the rate constant is included to account for the specific reaction rate.