Increasing the concentration of reactants in a chemical reaction generally leads to an increase in the reaction rate. This is because there are more reactant particles in a given volume, which increases the frequency of collisions between the particles. According to the collision theory, a higher frequency of collisions results in a higher probability of successful collisions, leading to an increased reaction rate.In the specific reaction between hydrochloric acid HCl and magnesium Mg , the reaction can be represented by the following balanced equation:Mg s + 2 HCl aq MgCl2 aq + H2 g When the concentration of hydrochloric acid is increased, there are more HCl molecules available to collide with the magnesium atoms on the surface of the solid. This leads to an increased frequency of successful collisions between the reactant particles, and thus, the reaction rate increases.It is important to note that the reaction rate will eventually reach a maximum value, as the magnesium surface becomes saturated with HCl molecules, and further increasing the concentration of HCl will not have a significant effect on the reaction rate.