Changing the concentration of reactants in a chemical reaction can significantly impact both the reaction rate and the yield of the reaction.1. Reaction rate: The reaction rate is the speed at which reactants are converted into products in a chemical reaction. According to the collision theory, the reaction rate is directly proportional to the frequency of effective collisions between reactant molecules. When the concentration of reactants is increased, the number of reactant molecules in a given volume also increases. This results in a higher probability of effective collisions between reactant molecules, leading to an increase in the reaction rate. Conversely, decreasing the concentration of reactants will result in a slower reaction rate.2. Reaction yield: The reaction yield refers to the amount of product formed in a chemical reaction. The effect of changing the concentration of reactants on the reaction yield depends on the type of reaction and the specific conditions under which the reaction is carried out.For reactions that reach equilibrium, the position of the equilibrium can be affected by changes in the concentration of reactants. According to Le Chatelier's principle, if the concentration of a reactant is increased, the equilibrium will shift in the direction that consumes the added reactant, potentially leading to a higher yield of products. Conversely, if the concentration of a reactant is decreased, the equilibrium may shift in the direction that produces more of the reactant, potentially leading to a lower yield of products.However, for reactions that do not reach equilibrium or are irreversible, the yield may not be significantly affected by changes in reactant concentration. In these cases, the reaction yield is primarily determined by the stoichiometry of the reaction and the limiting reactant.In summary, changing the concentration of reactants can affect the reaction rate and yield of a chemical reaction. Increasing the concentration of reactants generally leads to an increase in the reaction rate, while the effect on the reaction yield depends on the specific reaction and conditions.