The reaction between iodine I2 and thiosulfate ions S2O3^2- in an acidic solution can be represented by the following balanced chemical equation:2 S2O3^2- aq + I2 aq S4O6^2- aq + 2 I^- aq This reaction is a redox reaction, where iodine is reduced to iodide ions I^- and thiosulfate ions are oxidized to tetrathionate ions S4O6^2- . The presence of acid H+ in the solution helps to maintain the redox equilibrium.When the pH of the solution is increased, the concentration of H+ ions decreases. This can affect the redox equilibrium, as the reaction may be shifted towards the reactants' side left to compensate for the decrease in H+ ions. In other words, the reaction between iodine and thiosulfate ions may be slowed down or inhibited at higher pH values.However, it is important to note that the effect of pH on the equilibrium position of this reaction may not be significant, as the reaction itself does not directly involve H+ ions in the balanced chemical equation. The primary effect of increasing the pH would be on the rate of the reaction, rather than its equilibrium position. Nonetheless, it is generally recommended to carry out this reaction in an acidic solution to ensure optimal reaction conditions and maintain the redox equilibrium.