Disappearing X Experiment Introduction I am going to investigate the rate of reaction between sodium thiosulphate (thio) and hydrochloric acid. Hydrochloric Acid + Sodium Thiosulphate "" sodium chloride + water + sulphur The reactants are both colourless, but one of the products, sulphur, is yellow, so we can use this fact to follow the rates of reaction. I am going to investigate how the concentration of the acid effects the speed of the reaction. Apparatus 1 small measuring cylinder 1 large …showed first 75 words of 673 total…

…showed last 75 words of 673 total…a faster reaction. If the solution is diluted, there aren't as many acid particles to collide with the thio particles and so the reaction is much slower. Results /mins Acid/cm3Water/cm3Reaction Time 1Reaction Time 2Average Reaction Time 2501.522.332.12 2052.092.432.26 15102.242.542.39 10153.053.383.21 5204.585.555.26 /secs Acid/cm3Water/cm3Reaction Time 1Reaction Time 2Average Reaction Time 250112153132.5 205129163146 1510144174159 1015185218201.5 520298355326.5 Analysis/Conclusion We discovered that 25cm3 hydrochloric acid and 25cm3 sodium thiosulphate solution had the fastest reaction rate, just as we had predicted.