The reaction between sodium thiosulphate Na2S2O3 and hydrochloric acid HCl is a classic example of a precipitation reaction, where a solid product in this case, sulfur is formed. The balanced chemical equation for this reaction is:Na2S2O3 aq + 2HCl aq 2NaCl aq + SO2 g + S s + H2O l When the concentration of reactants is changed, it affects both the reaction rate and the reaction yield.1. Reaction rate:The reaction rate is the speed at which the reaction occurs. According to the collision theory, the rate of a reaction depends on the frequency of collisions between the reacting particles. When the concentration of reactants is increased, there are more particles in the same volume, leading to a higher probability of collisions. As a result, the reaction rate increases.In the case of the sodium thiosulphate and hydrochloric acid reaction, if you increase the concentration of either sodium thiosulphate or hydrochloric acid, the reaction rate will increase. This can be observed as the time taken for the sulfur precipitate to form and make the solution cloudy will decrease.2. Reaction yield:Reaction yield refers to the amount of product formed in a chemical reaction. In general, increasing the concentration of reactants can lead to a higher reaction yield, as there are more reactant particles available to form products. However, the reaction yield also depends on other factors such as temperature, pressure, and the presence of catalysts.For the sodium thiosulphate and hydrochloric acid reaction, the reaction yield is mainly determined by the stoichiometry of the reactants. If one of the reactants is present in excess, the reaction yield will be limited by the amount of the other reactant. In this case, increasing the concentration of the limiting reactant will lead to a higher reaction yield, while increasing the concentration of the reactant in excess will not have a significant impact on the reaction yield.In summary, changing the concentration of reactants in the sodium thiosulphate and hydrochloric acid reaction will affect the reaction rate and reaction yield. Increasing the concentration of either reactant will generally increase the reaction rate, while increasing the concentration of the limiting reactant will lead to a higher reaction yield.