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Investigation to find out if changes in concentration of acid Effect the rate of chemical reactions.

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Investigation to find out if changes in concentration of acid Effect the rate of chemical reactions. Planning Introduction The rate of a reaction is defined as the speed at which the reaction takes place. Many things can affect the rate of reaction. In this coursework I am investigating what Effect the change in acid concentration will have on the rate of reaction. The reaction between sodium thiosulphate and dilute hydrochloric acid will be used. The concentration of the thiosulphate will be changed; I will do this by adding different amounts of water. The concentration of the acid (hydrochloric) will remain constant. Table of variables Variable Effect Reason Value Temperature A high temperature will speed up the rate of reaction. As the temperature is increased particles move quicker. Increasing the temperature increases the rate of reaction. 10 degrees raise in temperature doubles the rate of reaction. Catalysts Adding a catalyst increases the rate of reaction. It is not used up itself Catalysts speed up reactions by providing an alternative pathway for the reaction. Thus creating more collisions. Speed up the reaction Concentration As the concentration is increased the reaction increases. The greater the concentration the more reactant particles there are in the solution. There will be more collisions and thus the reaction rate is increased. ...read more.


To find the rate of reaction of thiosulphate solution with hydrochloric acid that will vary in concentration. Apparatus: list of the apparatus I will use for the experiment. The apparatus used for the following experiment is shown below: * 150cm� conical flask * 10 cm� conical flask * 50cm� conical flask * 10cm� measuring cylinder * Test-tube * Stop clock * Test tube rack * White tile * Marker pen Chemicals: The chemicals I will use for this experiment. * Sodium thiosulphate * Hydrochloric acid The measuring cylinder is easy to use and it is easy to read from, the marker pen will be used to mark a cross on the white tile. The stop clock is also easy to use and the test tube rack holds the solutions, which is very helpful when carrying out an experiment. Planning Safety Before starting there are a few safety aspects, which we have to be careful of. Firstly, safety glasses should be worn at all times, and secondly, we have to be careful because the acid is highly corrosive to our bodies and should be kept away from skin and from our clothes. Method 1. I put 10cm� of thiosulphate solution into the conical flask. 2. I added 40cm� of water. ...read more.


My prediction was correct as what I predicted happened. Evaluation and Improvements: The main drawback with my experiment was the accuracy. To get the best range of results possible I needed to be as accurate as possible. With my equipment I think that I achieved this, but I could have used more complex measuring devices. I had no anomalies in my results as they all fitted into my pattern on my graph. If I were to do the experiment again I could improve it by using a wider range of concentrations, which would lead to a more accurate line of best fit. I would also have done each reading more than three times and taken a larger average, which would have increased the accuracy. Possible problems with my coursework could have been caused by human error. Firstly, there could have been error in stopping the stopwatch, although this would have been minimal. Also, some of the solution could have escaped If I were to change a variable, I would use the temperature. I think that this would be interesting to see if the rate of reaction was directly proportional. Overall, however, I think that this experiment has been successful because my prediction has been accurate which shows that the results are accurate. I have also made sure that the test was done fairly. ...read more.

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