Changing the reactant stoichiometry affects the reaction rate of a chemical reaction by altering the concentration of the reactants involved. The quantitative relationship between the two variables can be described using the rate law and the reaction order.The rate law is an equation that relates the reaction rate to the concentrations of the reactants. It has the general form:Rate = k[A]^m[B]^nwhere Rate is the reaction rate, k is the rate constant, [A] and [B] are the concentrations of reactants A and B, and m and n are the reaction orders with respect to A and B, respectively.The reaction order m and n indicates how the reaction rate is affected by the concentration of a particular reactant. For example, if the reaction is first-order with respect to reactant A m = 1 , then doubling the concentration of A will double the reaction rate. If the reaction is second-order with respect to A m = 2 , then doubling the concentration of A will quadruple the reaction rate.To determine the quantitative relationship between reactant stoichiometry and reaction rate, you would need to perform experiments to find the reaction orders m and n for the reactants involved. Once you have the reaction orders, you can use the rate law equation to predict how changes in reactant concentrations will affect the reaction rate.It's important to note that the reaction order is not always equal to the stoichiometric coefficient of the reactant in the balanced chemical equation. The reaction order is determined experimentally, and it can be zero, a positive integer, or even a fraction.In summary, changing the reactant stoichiometry affects the reaction rate by altering the concentration of the reactants. The quantitative relationship between the two variables can be described using the rate law and the reaction order, which are determined experimentally.