Changing the concentration of one reactant in a chemical reaction with multiple reactants can affect the reaction rate and reaction order in several ways. The reaction rate is the speed at which the reactants are converted into products, while the reaction order is an exponent that describes how the rate of a reaction depends on the concentration of its reactants.1. Reaction rate: The reaction rate is generally influenced by the concentration of the reactants. According to the law of mass action, the rate of a reaction is directly proportional to the product of the concentrations of the reactants, each raised to a power equal to their stoichiometric coefficients. If the concentration of one reactant is increased, the reaction rate will usually increase as well, assuming that the reaction is not limited by the concentration of another reactant.2. Reaction order: The reaction order is determined by the relationship between the reaction rate and the concentrations of the reactants. It can be determined experimentally by observing how the reaction rate changes when the concentrations of the reactants are varied. Changing the concentration of one reactant can help determine its reaction order. For example, if doubling the concentration of a reactant doubles the reaction rate, the reaction is first-order with respect to that reactant. If doubling the concentration of a reactant quadruples the reaction rate, the reaction is second-order with respect to that reactant.In summary, changing the concentration of one reactant in a chemical reaction with multiple reactants can affect the reaction rate by increasing or decreasing the speed at which the reaction occurs. It can also help determine the reaction order, which describes how the reaction rate depends on the concentration of the reactants.