The reaction between iodine I2 and thiosulfate ions S2O3^2- in the presence of hydrochloric acid HCl can be represented as follows:2 S2O3^2- aq + I2 aq S4O6^2- aq + 2 I^- aq To determine the equilibrium constant Kc for this reaction, we need to know the equilibrium concentrations of all species involved. Unfortunately, without the specific concentrations or experimental data, we cannot directly calculate the equilibrium constant.However, if you have the initial concentrations and any changes in concentration during the reaction, you can use an ICE Initial, Change, Equilibrium table to determine the equilibrium concentrations and subsequently calculate the equilibrium constant.Keep in mind that the equilibrium constant is temperature-dependent, so the temperature at which the reaction occurs should also be considered when calculating Kc.