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An Investigation into Rate of reaction

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GCSE science Coursework An Investigation into Rate of reaction NOVEMBER 2002 By Helen Crutcher Bibliography Books: 1. Hill, G. (1998) Science for GCSE Hodder and Stoughton. Pages 170-3 2. Smart, T. (1998) visual encyclopaedia of science DK. Page 52 URL's: 3. http://www.studentcentral.co.uk/coursework/essays/1530.html 4. http://www.gcsechemistry.co.ukop1.htm Other: 5. encyclopaedia standard edition 2002, Encarta (computer program) An investigation into rate of reaction The aim of the investigation The aim of this investigation is to see what effect temperature change has on the rate of reaction between Sodium Thiosulphate and Hydrochloric acid. Background information The Collision theory When two substances are put together, the particles of each will collide but they may not react. A reaction can only take place when the particles of the reactants collide with enough energy to break their chemical bonds. When these chemical bonds are broken, new ones can be created between the component substances. The energy required for successful collisions is called activation energy. The more collisions between particles in a given time the faster the reaction is There are four factors affecting the number of successful collisions, these are: Temperature - increased heat means that particles have more energy; they will move around more and with more energy and so more particles can collide with enough energy to react. ...read more.


When the reactants have reached the correct temperature, take them out of the water bath and quickly pour them both into the conical flask. 6. simultaneously start the timer 7. 1 person watches the reaction and stops the timer when the cross is no longer visible 8. Record results in table Here are the results from the preliminary experiment: Temperature (oC) Time (Seconds) 1 119.51 20 53.98 50 12.81 100 04.38 From these results, I can see that it would be possible to use this range of temperatures for the final experiment. Evaluation of preliminary experiment: Although the temperatures I chose gave me successful results after doing the preliminary experiment, I found that it would be dangerous to heat the reactants to temperatures as high as 100 degrees, since at temperatures above 60 degrees large amounts of Sulphur Dioxide gas are produced. Sulphur dioxide is toxic and harmful. Therefore, for our final experiment, we will range our temperatures from 0-60 degrees but we will use the same interval, we should still have enough results to draw a reliable graph. As you can see from the table, we didn't manage to get the reactant temperature as low as 0 degrees. ...read more.


Evaluation The results were overall good, although there are some anomalies. We can see from the results table that the results for 5 degrees were especially unreliable, they are all very different from each other, and this suggests error in the experiment. Other anomalous results are the first time for 30 degrees and all three times for 50 degrees. The problem with the anomalous results could be that: * The person watching the reaction inaccurately judged when the cross was fully obscured. * Errors in the co-ordination of the person watching the experiment affected the time. Using a light sensor would remove these human errors; a light sensor measures the amount of light shining through a substance. It would be wired up to a timer and to the experiment, it would automatically stop the timer at the exact point that no light passes through the liquid, therefore giving us fairer, more reliable results. Simply repeating the experiment more would give us data that are more accurate, and being extra careful not to affect the concentration by adding water would also help. To investigate this experiment further we could do more repeats and do a wider range of temperatures with a smaller interval, this would give us more results from which to draw evidence that is more reliable. ...read more.

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