The effect of varying the concentration of reactants on the rate of reaction and the resulting yield of product in the chemical reaction between hydrochloric acid HCl and sodium thiosulphate Na2S2O3 can be explained using the collision theory and the law of mass action.According to the collision theory, the rate of a chemical reaction depends on the frequency of collisions between the reacting particles. When the concentration of reactants is increased, the number of particles per unit volume also increases, leading to a higher probability of collisions between the particles. As a result, the rate of reaction increases.In the reaction between hydrochloric acid and sodium thiosulphate, the following reaction occurs:HCl aq + Na2S2O3 aq 2NaCl aq + H2O l + SO2 g + S s When the concentration of either HCl or Na2S2O3 is increased, the rate of reaction will increase due to the higher frequency of collisions between the reactant particles. This can be observed as a faster formation of the sulfur precipitate S , which causes the solution to become cloudy.However, it is important to note that the yield of the product in this case, sulfur will not be affected by the concentration of the reactants. The yield depends on the stoichiometry of the reaction, which is determined by the balanced chemical equation. In this reaction, one mole of HCl reacts with one mole of Na2S2O3 to produce one mole of sulfur. Therefore, the yield of sulfur will be determined by the limiting reactant, which is the reactant that is completely consumed during the reaction.In summary, increasing the concentration of reactants in the reaction between hydrochloric acid and sodium thiosulphate will increase the rate of reaction but will not affect the yield of the product, as the yield is determined by the stoichiometry of the reaction and the limiting reactant.