The relationship between reactant concentration and reaction rate in the reaction between magnesium and hydrochloric acid can be described by the rate law. The rate law is an equation that shows how the rate of a reaction depends on the concentration of the reactants. For the reaction between magnesium Mg and hydrochloric acid HCl , the balanced chemical equation is:Mg s + 2HCl aq MgCl2 aq + H2 g The rate law for this reaction can be written as:Rate = k[Mg][HCl]^nwhere Rate is the reaction rate, k is the rate constant, [Mg] and [HCl] are the concentrations of magnesium and hydrochloric acid, respectively, and n is the order of the reaction with respect to hydrochloric acid.In general, as the concentration of the reactants increases, the reaction rate also increases. This is because there are more particles available to collide with each other, leading to a higher probability of successful collisions and thus a faster reaction.For the reaction between magnesium and hydrochloric acid, the reaction rate is directly proportional to the concentration of hydrochloric acid. This means that if the concentration of HCl is doubled, the reaction rate will also double. The reaction order n with respect to HCl is typically found to be 1, indicating a first-order reaction with respect to HCl.The efficiency of the reaction can be affected by the concentration of the reactants. A higher concentration of reactants can lead to a faster reaction rate, which may be desirable in certain applications. However, it is important to note that increasing the concentration of reactants can also lead to a higher likelihood of side reactions or the formation of unwanted byproducts. Therefore, it is crucial to find the optimal concentration of reactants to achieve the desired reaction rate while minimizing any potential side effects.In summary, the relationship between reactant concentration and reaction rate in the reaction between magnesium and hydrochloric acid is directly proportional, and this can affect the efficiency of the reaction. Higher concentrations of reactants generally lead to faster reaction rates, but it is important to balance this with the potential for side reactions or byproduct formation.