Changing the reactant concentration in a chemical reaction with fixed stoichiometry can significantly affect the rate of the reaction. According to the collision theory, the rate of a reaction depends on the frequency of effective collisions between reacting particles. When the concentration of reactants increases, the number of particles per unit volume also increases, leading to a higher probability of effective collisions between the particles.In general, the rate of a reaction can be expressed as:Rate = k[A]^m[B]^nwhere k is the rate constant, [A] and [B] are the concentrations of reactants A and B, and m and n are the orders of the reaction with respect to A and B, respectively. The overall order of the reaction is the sum of m and n.For example, if a reaction has a first-order dependence on reactant A m = 1 and a second-order dependence on reactant B n = 2 , the rate equation would be:Rate = k[A][B]^2In this case, if the concentration of A is doubled, the rate of the reaction will also double. If the concentration of B is doubled, the rate of the reaction will increase by a factor of 4 2^2 .It is important to note that the relationship between reactant concentration and reaction rate is not always a simple proportionality, as the reaction order m and n can be zero, fractional, or even negative. However, in most cases, increasing the concentration of reactants will lead to an increase in the rate of the reaction, assuming other factors such as temperature and pressure remain constant.