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sodium thiosulphate

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Introduction

Waleed Mahmood Chemistry Coursework Rates of Reaction Sodium Thiosulphate and Hydrochloric acid In this piece of coursework, I will study how concentration affects the rate of reaction. I will do so by timing the reaction of Sodium Thiosulphate with an acid. In this coursework, I will include background knowledge, prediction, safety, results, calculations, graphs, an analysis, conclusion and an evaluation. In my evaluation I will comment on how reliable my results were and how I could have improved my coursework in any possible way. The definition of rate of reaction is 'The speed at which a chemical reaction takes place'. The factors that affect the rate of reaction are: * Use of a catalyst * Temperature * Surface area * Concentration I will be investigating Concentration in this experiment. In a higher concentration there are more Sodium Thiosulphate particles. This means there is a higher number of collisions which will have enough energy to react. This causes the rate to increase. The time it takes for a change to take place can be measured and can be estimated. For a reaction to take place 2 reactants must collide and the collision must have enough energy. ...read more.

Middle

The temperature is also the same because the results could be anomalous if tested in different conditions. Same beakers will not be used for different chemicals. This can cause reactions in the beakers and will lead to inaccuracies. Preliminary Results Table: Sodium Thiosulphate (cm3) Water(cm3) Hydrochloric acid(cm3) Time(seconds) 50 0 5 12.73 45 5 5 19.16 40 10 5 20.21 35 15 5 25.86 30 20 5 32.13 25 25 5 40.42 20 30 5 57.29 15 35 5 81.34 10 40 5 139.27 5 45 5 403.20 Experiment 1 Results: Sodium Thiosulphate (cm3) Water(cm3) Hydrochloric acid(cm3) Time(seconds) 50 0 5 11.88 45 5 5 20.43 40 10 5 21.67 35 15 5 27.05 30 20 5 32.34 25 25 5 39.87 20 30 5 57.03 15 35 5 81.74 10 40 5 140.47 5 45 5 403.59 Experiment 2 Results: Sodium Thiosulphate (cm3) Water(cm3) Hydrochloric acid(cm3) Time(seconds) 50 0 5 12.15 45 5 5 19.89 40 10 5 21.33 35 15 5 28.01 30 20 5 31.56 25 25 5 40.13 20 30 5 57.48 15 35 5 82.68 10 40 5 140.03 5 45 5 402.97 Experiment 3 Results: Sodium Thiosulphate (cm3) ...read more.

Conclusion

This would help me to obtain better results that are more accurate. My hand was not very steady in the preliminary experiment and I poured too much acid in some of the experiment. I improved this by using a beaker to pour the acid first and then transferred it to the flask. I would also repeat the experiment after obtaining the results to make sure of the results. I think my evidence of this experiment is reliable because I did it with precision and carried it out carefully. I thought that I might have some anomalies but there were not any. I can prove this by using my prediction earlier in the experiment. I said that "as concentration is increased the amount of time taken for the reaction is halved." I would have been perfectly right but I made a mistake while measuring. To improve my results, I would use a wider range of concentration and different acid solutions. This would help me to find a pattern and come to a firm conclusion. Overall I think that this experiment was a success as I have proved that concentration does affect rate, and I have also found that when the concentration is doubled the rate of reaction is halved. To draw a firm conclusion I would need to get more results, less inaccuracies and better measuring methods. ...read more.

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