The effect of varying the concentration of reactants on the reaction rate and selectivity for the synthesis of aspirin can be understood by examining the reaction kinetics and the Le Chatelier's principle.The synthesis of aspirin acetylsalicylic acid involves the reaction between salicylic acid and acetic anhydride, with a catalyst such as sulfuric acid or acetic acid:C7H6O3 salicylic acid + CH3CO 2O acetic anhydride C9H8O4 aspirin + CH3COOH acetic acid 1. Reaction rate: The reaction rate is influenced by the concentration of the reactants, as described by the rate law. In general, the rate of a reaction increases with an increase in the concentration of the reactants. This is because a higher concentration of reactants leads to a higher frequency of successful collisions between the reacting molecules, resulting in an increased rate of product formation.For the synthesis of aspirin, if the concentration of either salicylic acid or acetic anhydride is increased, the reaction rate will likely increase as well. However, the specific relationship between the concentration of reactants and the reaction rate depends on the reaction order, which can be determined experimentally.2. Selectivity: Selectivity refers to the preference of a reaction to form one product over another. In the case of aspirin synthesis, the main desired product is aspirin, but there may be side reactions or byproducts formed. Le Chatelier's principle states that if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust to counteract the change and restore equilibrium.If the concentration of salicylic acid or acetic anhydride is increased, the reaction will shift towards the formation of more aspirin and acetic acid to counteract the change and restore equilibrium. This could potentially lead to higher selectivity for aspirin formation, as the reaction will favor the formation of the desired product. However, it is essential to consider other factors, such as temperature and catalyst concentration, which can also influence selectivity.In summary, increasing the concentration of reactants in the synthesis of aspirin can lead to an increased reaction rate and potentially higher selectivity for aspirin formation. However, the specific relationship between concentration and reaction rate/selectivity depends on the reaction kinetics and other factors, such as temperature and catalyst concentration.