The reaction between hydrochloric acid HCl and sodium thiosulfate Na2S2O3 can be represented by the following balanced chemical equation:2HCl aq + Na2S2O3 aq 2NaCl aq + H2O l + SO2 g + S s The effect of the initial concentration of reactants on the reaction rate and yield can be analyzed using the principles of chemical kinetics and equilibrium.1. Reaction rate: According to the rate law and the collision theory, the rate of a reaction is directly proportional to the product of the concentrations of the reactants raised to their respective orders in the rate law. For this reaction, the rate law can be expressed as:Rate = k[HCl]^m[Na2S2O3]^nwhere k is the rate constant, m and n are the orders of the reaction with respect to HCl and Na2S2O3, respectively. As the initial concentration of either or both reactants increases, the reaction rate will also increase. This is because a higher concentration of reactants leads to more frequent collisions between the reacting molecules, resulting in a faster reaction.2. Reaction yield: The reaction between HCl and Na2S2O3 is a complete reaction, meaning that it goes to completion and there is no equilibrium involved. In such cases, the reaction yield is determined by the stoichiometry of the reaction and the limiting reactant. If the reactants are mixed in their stoichiometric ratio 2 moles of HCl for every 1 mole of Na2S2O3 , the reaction will proceed until one of the reactants is completely consumed, and the yield will be determined by the amount of the limiting reactant.If the reactants are not mixed in their stoichiometric ratio, the reaction will still proceed until one of the reactants is completely consumed, but the yield will be lower than the theoretical maximum because some of the excess reactant will remain unreacted.In summary, increasing the initial concentration of reactants will increase the reaction rate, but the reaction yield will be determined by the stoichiometry of the reaction and the limiting reactant.