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# Rates of reaction:- sodium thiosulphate + hydrochloric acid

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Introduction

Rates of reaction:- sodium thiosulphate + hydrochloric acid Plan:- We must produce a piece of coursework investigating the rates of reaction, and the effect that changing one particular variable has on the reaction time. The rate of reaction is the time it takes one or more of the reactants to react or the time it takes to produce a new product from a chemical reaction. To work out the reaction time we use the formula. 1 divided by time taken for reaction There are five factors which affect the rate of a reaction, according to the collision theory of reacting particles: 1. temperature of solution, 2. concentration of solution, 3. pressure of gases in reaction, 4. surface area of reactants, 5. Catalysts. For my preliminary experiments I have chosen to investigate the effect temperature and concentration have on a reaction. I have chosen to investigate these reactants because the are the most practical for the lab and equipment that I have available to use also it would take to much time to prepare a solid in powdered and unpowdered form, and it is difficult to get accurate readings due to the inevitabilities of human errors, and as gas is mostly colourless it is difficult to gauge a reaction changing the pressure, and if a substance is added to give the gas colour, it may influence the outcome of the experiment. ...read more.

Middle

I will then place a thermometer into the diluted thiosulphate and place it in to water bath. While the acid and thiosulphate solution are heating up I will place a conical flask on to a piece of a card which has a large black cross drawn on its center. Once the acid and thiosulphate have reached the temperature of the water bath that they're in, room temperature -70�C. I will pour them into the conical flask and start the stop clock. I will look at the solution and when it turns to cloudy to see the cross at the bottom of the conical flask I will stop the stop clock. I will repeat this process three times for each of my six temperatures. Repeat results and averages will be taken to improve the credibility of the findings, and present solid grounding for the final conclusion. The repeat results will help to iron out any anomalies and the average will give a good summary of the results of the experiment. However if one set of results is entirely different to the other, a third experiment will be performed to replace the anomalous set of results. Safety :- A pair of goggles will be worn during the heating part of the experiment in order to protect the eyes. I would ideally like to wear an apron to protect the skin and clothing but none are available for use so I will just have to careful when heating and transferring liquids. ...read more.

Conclusion

In the temperature experiment the average time taken for a reaction to take place decreased was 19.363 seconds for every 10�C increase in temperature. The above graphs show that rate against temperature has a negative positive correlation, however time against temperature has a negative correlation. This is because as you increase the temperature the rate of reaction increases meaning that it takes less time for each reaction to take place. This is because when the temperature is increased the particles have more energy and therefore move faster, meaning that the will collide more often with more energy. If the particles have got more energy they are more likely to overcome the Particles with more energy are more likely to react successfully. I wouldn't expect either of the lines of best fit to go through the origin because the increase in time/rate is not directly proportional to the increase of temperature. There aren't any obvious anomalous results in my graphs so therefore I believe that my results do support my prediction. Had I done this experiment again I would have used a Bunsen burner instead of a water bath as it is more accurate to get the temperatures that I would have wished. However apart from that I don't think that there is any thing else that I could have done to improve my test results except have had more time to have done the extra set of results that I need to get a wider range of results. By Kit Beaumont 11EBa ...read more.

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