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How changing the concentration of acid affects the rate of reaction

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How changing the concentration of acid affects the rate of reaction Plan Aim The aim of my experiment is to see how changing the concentration of acid affects the rate of reaction. Prediction I am going to investigate the change in concentration of acid; I will be doing this by increasing the concentration of acid so the rate of reaction will be faster. There are five factors which affect the rate of reaction, according to the collision theroy of reacting particles: temperture, concentration (of solution), pressure (in gases), surface (of solid reactants), and catalysts. I have chosen to investigate the affect of concentration have on a reaction. I predict that as the consentration of the sodium thiosulphate increases the rate of reaction will increase, therefore the black cross will disapear more quickly due to the cloudiness of the solution. This means that the graph in my analysis will have a strong positive correlation, and will probably be curved because of the increase in rate of reaction. This can be justified by using the collision theory. When the consentration is increased the particles will have more energy and will move faster. Therefore they will collide more often and with more energy. ...read more.


Range of readings For my experiment I will be using a range of acids at 0.1, 0.2, 0,5 , 1.0 and 1.5m, this is so i have a wide range of readings. I repeated the experiment five times to get a wide range of results to make the experiment more accurate and fair. This will help me observe my results and plot then on graphs. Method 5 cm3 of Hydrochloric acid and 25 cm3 of sodium thiosulphate (at varying concentrations are poured out into two measuring cylinders and then poured into a conical flask, which is placed on top of a board marked with letter X. The stopwatch will now be started. When the mixture has turned sufficiently cloudy so that the letter X can no longer be seen the stopwatch will be stopped and the time will be recorded. The experiment is repeated with all the concentrations. The whole procedure is then repeated. Results Concentration of acid Time to react Time to react Time to react 1st 2nd 3rd Average 0.1m 01:44 01:52 01:47 01:47 0.2m 01:17 01:22 01:09 01:16 0.5m 0.41 0.39 0.45 0.42 1.0m 0.36 0.33 0.34 0.34 1.5m 0.29 0.3 0.28 0.29 These are my results i collected from my experiment, the table shows all 5 concentrations and the result highlighted in red is an anomaly. ...read more.


The result may have turned out anomalous because of basic human error, or maybe because we measured the substances wrong. It may have even been because we did not clean the apparatus properly.Apart from this, the accuracy of my experiment has been more or less accurate. Although there are a number of ways in which we could have made the results more reliable. For instance, we could have used better measuring equipment, because the apparatus we used was mainly basic equipment. Even though the experiment went well it was hard to tell when the cross had disapeard, so instaed we could of used a light beam and when that goes out, then that means the process has finished. The average still fitted the prediction even though there was an odd result. Another thing we could have done to bring more evidence is to have tried to use the hydrochloric acid as the variable substance, and used the sodium thiosulphate as the constant substance. This would have brought more evidence to support the idea that the higher concentration of a substance, the faster it will react. I think that the evidence, which I have received, is enough to reach a suitable conclusion, but there are a few anomaly's to the experiment (which I have mentioned). Apart from them, the experiment is fine. By Ricky Goldblatt Science Chemistry Coursework ...read more.

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