Changing the concentration of reactants can significantly affect the selectivity of a chemical reaction. Selectivity refers to the preference for the formation of one product over another in a chemical reaction. There are several ways in which changing reactant concentrations can influence selectivity:1. Le Chatelier's Principle: According to this principle, if a system at equilibrium is subjected to a change in concentration, the system will adjust to counteract the change and restore equilibrium. If the concentration of a reactant is increased, the reaction will shift towards the side that consumes the reactant, potentially favoring the formation of a particular product.2. Reaction Rate: The rate of a reaction depends on the concentration of the reactants. If the concentration of a reactant is increased, the reaction rate may increase, leading to faster formation of products. If one reaction pathway has a higher reaction rate than another, increasing the concentration of a reactant may favor the formation of the product associated with the faster reaction.3. Reaction Mechanism: The mechanism of a reaction involves a series of elementary steps that lead to the formation of products. Changing the concentration of reactants can affect the relative rates of these elementary steps, which in turn can influence the overall selectivity of the reaction.4. Competitive Reactions: In some cases, a reactant can participate in multiple reactions that lead to different products. If the concentration of a reactant is increased, it may favor one reaction over another, leading to a change in selectivity.5. Catalysts and Inhibitors: The presence of catalysts or inhibitors can also affect the selectivity of a reaction. If the concentration of a reactant is changed, it may alter the effectiveness of a catalyst or inhibitor, leading to changes in selectivity.In summary, changing the concentration of reactants can have a significant impact on the selectivity of a chemical reaction by influencing factors such as equilibrium position, reaction rate, reaction mechanism, competitive reactions, and the effectiveness of catalysts or inhibitors.