The effect of pH on the rate of reaction between hydrochloric acid HCl and magnesium Mg can be understood by considering the nature of the reaction and the role of pH in influencing the concentration of HCl.The reaction between hydrochloric acid and magnesium is an acid-base reaction, where magnesium acts as a base and hydrochloric acid acts as an acid. The balanced chemical equation for this reaction is:Mg s + 2HCl aq MgCl2 aq + H2 g In this reaction, the hydrogen ions H+ from the hydrochloric acid react with the magnesium to produce magnesium chloride MgCl2 and hydrogen gas H2 . The rate of this reaction depends on the concentration of HCl, as a higher concentration of HCl means more hydrogen ions are available to react with magnesium.The pH of a solution is a measure of the concentration of hydrogen ions H+ in the solution. A lower pH indicates a higher concentration of hydrogen ions, while a higher pH indicates a lower concentration of hydrogen ions. In the case of hydrochloric acid, a strong acid, the pH is directly related to the concentration of HCl.Therefore, the effect of pH on the rate of reaction between hydrochloric acid and magnesium can be summarized as follows:1. As the pH decreases i.e., the solution becomes more acidic , the concentration of HCl increases, leading to a faster rate of reaction between HCl and Mg.2. As the pH increases i.e., the solution becomes less acidic or more alkaline , the concentration of HCl decreases, leading to a slower rate of reaction between HCl and Mg.In conclusion, the rate of reaction between hydrochloric acid and magnesium is directly influenced by the pH of the solution, with a lower pH higher acidity resulting in a faster reaction rate, and a higher pH lower acidity resulting in a slower reaction rate.