The reaction rate between sodium thiosulfate Na2S2O3 and hydrochloric acid HCl is affected by the pH level of the solution. The reaction between these two chemicals can be represented by the following equation:Na2S2O3 aq + 2 HCl aq 2 NaCl aq + H2O l + SO2 g + S s In this reaction, sodium thiosulfate reacts with hydrochloric acid to produce sodium chloride, water, sulfur dioxide, and solid sulfur. The pH level of the solution influences the reaction rate by affecting the concentration of H+ ions protons in the solution.At lower pH levels more acidic conditions , the concentration of H+ ions is higher. This increased concentration of protons can lead to a faster reaction rate, as there are more H+ ions available to react with the sodium thiosulfate. Conversely, at higher pH levels more basic conditions , the concentration of H+ ions is lower, which can result in a slower reaction rate.However, it is important to note that the reaction between sodium thiosulfate and hydrochloric acid is primarily an acid-base reaction, and the pH level is inherently determined by the concentration of hydrochloric acid in the solution. In other words, the pH level is not an independent variable in this reaction, as it is directly related to the concentration of one of the reactants HCl .In summary, the pH level of a solution does affect the reaction rate between sodium thiosulfate and hydrochloric acid, with lower pH levels higher H+ ion concentrations generally leading to faster reaction rates. However, the pH level is not an independent variable in this reaction, as it is directly related to the concentration of hydrochloric acid.