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How does the concentration of sodium thiosulphate acid affect the rate of reaction?

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How does the concentration of sodium thiosulphate acid affect the rate of reaction? AIM: In this investigation my aim is to find out how the rate of reaction between Sodium thiosulphate and Hydrochloric acid is affected by the concentration. INTRODUCTION: The purpose of this investigation is to understand the effects of changing concentrations of variables have on the rate of reaction. The reaction is going to be between two chemicals, Sodium thiosulphate solution and hydrochloric acid dilute. The equation below shows how they react. sodium thiosulphate + hydrochloric acid � sodium chloride + sulphur + sulphur dioxide + water Na2S2O3(aq) + 2HCl(aq) � 2NaCl(aq) + S(s) + SO2(g) + H2O(l) THEORY: The collision theory sets to clarify how chemical reactions take place and where the rate of reaction vary. Reactant particles must collide for a reaction to occur. Only a percentage of collisions cause chemical change; these are called successful collisions. These successful collisions have sufficient energy at the moment of impact to split existing bonds and forms new ones. Therefore increasing the concentration of reactants as well as raising temperatures result in more collision and consequently more successful collisions, thus increasing the rate of reaction. ...read more.


Prediction: Therefore the cross will disappear quickly due to the cloudiness of the solution. This is because the more hydrochloric particles there are, the more likely chance of successful collisions with sodium particles in the beaker. If the strength of the concentration is doubled the rate of reaction is twice as fast. I believe the concentration of a solution effects the rate of reaction as the rate of reaction relies on how often the molecules of the reacting substance collide. The more concentrated a substance is, the more the number of molecules it contains. The frequency of collisions is greater, as there are more molecules about, and the reaction will therefore happen more rapidly. Method Draw a black cross on a white piece of paper Place cross under conical flask Measure and add 50 ml of sodium thiosulphate into the beaker In a test tube add hydrochloric acid and water depending on the concentration Add dilute hydrochloric acid to beaker Start the stopcock, immediately as soon as the hydrochloric acid is added to the beaker Stop the time when the cross is no bigger Record your results Repeat test 3 times for every concentration Safety Health and safety had to be carried out before and whilst during the experiment. ...read more.


From the readings taken I found the average by working out the mean. After plotting these points on a graph the correlation can clearly be seen, the higher the concentration the faster the reacting time. However as I predicted that double the strength of a concentration would make the rate of reaction go twice as fast, this ended up being untrue as my evidence proves. All results I got from the experiment were exactly as I expected them to be like. The graphs back up my prediction as well as the table. I got good results as I concentrated on the task at hand and carefully measured all solutions. I did not encounter any anomalies which means the data taken was flawless and I avoided mistakes when creating my table and graph. To improve this experiment next time I should use a more accurate measuring cylinder, which measures to the micro litre, and use the same cross under the beaker all the time. Also I must be much more careful when it comes to watching the exact moment the cross is disappeared and stopping the clock. ?? ?? ?? ?? name Mr.Keble - 7 - Additional Science ...read more.

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