Inferring a rate law from data

A rate law relates reaction rate to reactant concentrations under specified conditions. Reaction orders are determined experimentally; they cannot generally be copied from coefficients in the overall balanced equation. Keep other variables fixed when comparing trials. If doubling one reactant's concentration makes the initial rate four times larger while other concentrations stay fixed, the reaction is second order with respect to that reactant. This observation alone does not determine the orders of other reactants.