The concentration of reactants affects the rate of a chemical reaction according to the collision theory and the rate law. 1. Collision theory: The collision theory states that for a reaction to occur, the reactant particles must collide with each other with sufficient energy and proper orientation. When the concentration of reactants is increased, there are more particles present in a given volume. This leads to a higher probability of collisions between reactant particles, resulting in an increased rate of reaction.2. Rate law: The rate law is a mathematical expression that relates the rate of a chemical reaction to the concentrations of the reactants. It is usually expressed as: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 orders m and n are determined experimentally and can be positive, negative, or zero.According to the rate law, the rate of a chemical reaction depends on the concentrations of the reactants raised to their respective reaction orders. If the reaction order is positive, an increase in the concentration of the reactant will lead to an increase in the reaction rate. Conversely, if the reaction order is negative, an increase in the concentration of the reactant will lead to a decrease in the reaction rate. If the reaction order is zero, the concentration of the reactant does not affect the reaction rate.In summary, the concentration of reactants affects the rate of a chemical reaction by influencing the frequency of collisions between reactant particles and by following the rate law, which relates the reaction rate to the concentrations of the reactants raised to their respective reaction orders.