The rate of reaction between hydrogen peroxide H2O2 and iodide ion I- can be affected by the change in pH. This reaction is typically catalyzed by an acid, such as hydrochloric acid HCl , and is known as the iodine clock reaction. The overall reaction can be represented as:H2O2 + 2I- + 2H+ I2 + 2H2OAs the pH of the solution changes, the concentration of H+ ions in the solution also changes. The pH is defined as the negative logarithm of the H+ ion concentration:pH = -log10[H+]When the pH decreases becomes more acidic , the concentration of H+ ions increases. This increase in H+ ions leads to a faster rate of reaction between hydrogen peroxide and iodide ion, as the reaction is acid-catalyzed. Conversely, when the pH increases becomes more basic , the concentration of H+ ions decreases, resulting in a slower rate of reaction.In summary, the rate of reaction between hydrogen peroxide and iodide ion is directly proportional to the concentration of H+ ions in the solution. As the pH decreases more acidic , the rate of reaction increases, and as the pH increases more basic , the rate of reaction decreases.