Increasing the concentration of reactants in a chemical reaction generally leads to an increase in the reaction rate. This is because a higher concentration of reactants results in more frequent collisions between the reacting molecules, leading to a higher probability of successful collisions and, therefore, a faster reaction rate.However, in the scenario you described, the concentration of one product is kept constant, and the concentration of another product is gradually increased. This situation implies that the reaction may be reversible, meaning the products can react to form the reactants again.As the concentration of one product increases, the reverse reaction rate may also increase, which can counteract the effect of increasing the reactant concentration. This means that the overall reaction rate may not increase as much as expected, or it may even decrease, depending on the specific reaction and the relative rates of the forward and reverse reactions.In summary, increasing the concentration of reactants generally increases the rate of a chemical reaction. However, in a reversible reaction where the concentration of one product is kept constant and another product's concentration is gradually increased, the effect on the reaction rate may be less predictable and depends on the specific reaction and the relative rates of the forward and reverse reactions.