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Investigating Reaction Rates

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Matthew Attwood Investigating Reaction Rates I am going to investigate how temperature effects the rate of reaction between a starch/amylase solution. Enzymes are protein molecules which work because of their shape. They are easily damaged by heat. This is because the protein structure unravels, which changes the shape of the molecule so they no longer work. If the temperature goes above 45(C most enzymes are damaged or destroyed and no longer catalyse reactions. Enzymes are also very specific - each enzyme will only catalyse a certain reaction. Chemical reactions only take place when the reaction particles collide with each other, and collide with enough energy to react. The minimum amount of energy the particles must have to react is called the activation energy. Anything which makes the particles in a reaction mixture more likely to collide with the right amount of energy will speed up the rate of reaction. The surface area of the solid reactants, the temperature and the concentration of the reactants all affect the rate of reaction. A catalyst increases the rate of reaction without altering anything else. It is not used up during the reaction and can be used over and over again to speed up a process. There are many sorts of catalyst because different reactions need different catalysts. ...read more.


I will then repeat each experiment to confirm my readings, and so that I can work out an average time for the reactions to take place at certain temperatures. Here is a diagram of the apparatus I shall use: I predict that as the temperature is raised the reaction time will decrease. I think this because according to the background information the enzymes make the reaction possible at lower temperatures so in theory if the temperature is raised the reaction should speed up as long as the enzymes are not destroyed or damaged by too much heat. To keep the tests fair I am going to use the same amount of amylase, iodine, and starch in the solution in each experiment. I carried out this test by getting boiling tubes and washed them out to rid them of impurities from past experiments they may have been used in. I decided which one was going to be the control and which one was going to hold the test tube containing the amylase enzyme, poured 5mls of 0.5% starch solution into each and placed them in a beaker containing hot water. I then added three drops of iodine to each boiling tube to make the 0.5% starch solution turn a dark purple colour. ...read more.


This has proven to me that temperature does have an effect on the reaction between starch and amylase. The reason why the iodine fades out is because a reaction takes place between the starch and amylase, which changes starch to sugar, has successfully taken place. As the temperature went up the reaction happened at a faster rate. This is because as the molecules heat up they gain more kinetic energy and move faster causing the amylase molecules and the starch molecules to bump into each other which means that the experiment will happen faster. By doing this experiment I found out that amylase reacts with starch to make sugar. I also found out that temperature also effects the rate of reaction. I could also have tested the solution after the experiment with blue benedicts to make sure that the product from the reaction was sugar as well. If I was to do the experiment again I would improve the experiment by making sure the water temperature doesn't drop. I could possible do this by some form of insulation. I would also like to be able to use a different method of timing the reaction rather than having to do it myself, and last of all I would like to be able to measure the solutions with more accuracy. I might also do a different experiment where I change the concentrations of the liquid used. Here is a diagram of what happens: ...read more.

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