The redox reaction between iodine I2 and thiosulfate ions S2O3^2- can be represented by the following balanced equation:2 S2O3^2- aq + I2 aq S4O6^2- aq + 2 I^- aq In this reaction, iodine is reduced to iodide ions I^- , and thiosulfate ions are oxidized to tetrathionate ions S4O6^2- . The equilibrium position of this reaction is determined by the equilibrium constant K_eq , which is the ratio of the concentrations of the products to the concentrations of the reactants, each raised to the power of their stoichiometric coefficients:K_eq = [S4O6^2-][I^-]^2 / [S2O3^2-]^2[I2] Now, let's consider the effect of adding a catalyst to this reaction. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It does this by providing an alternative reaction pathway with a lower activation energy. However, it's important to note that a catalyst does not affect the equilibrium position of a reaction, nor does it change the equilibrium constant K_eq . In the case of the redox reaction between iodine and thiosulfate ions, adding a catalyst will increase the rate at which the reaction reaches equilibrium, but it will not change the equilibrium concentrations of the reactants and products. Therefore, there will be no quantitative change in the concentrations of each species, and the equilibrium position will remain the same.In summary, the addition of a catalyst to the redox reaction between iodine and thiosulfate ions will speed up the reaction, allowing it to reach equilibrium more quickly, but it will not affect the equilibrium position or the concentrations of the reactants and products at equilibrium.