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In this investigation the aim is to find out whether the concentration of hydrogen peroxide affects the rate at which catalase breaks it down.

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Catalase Reaction Aim: In this investigation the aim is to find out whether the concentration of hydrogen peroxide affects the rate at which catalase breaks it down. Prediction: If we firstly see what a catalyst is, Catalyst is one of the factors which affect the speed of a reaction. Enzyme is one type of catalyst and catalase is an example of enzyme, which I will be using in my experiment. Enzymes work because they cover in active sites, which is more specific about molecules they will allow to stick on. It is often describe as a lock and key mechanism. In this experiment the lock is the catalase enzyme and the key is hydrogen peroxide. So increasing the concentration of hydrogen peroxide will increase the rate of catalase reaction because the laws of the kinetic theory states; that if there are less atoms (decreasing hydrogen peroxide concentration) there will be less collisions because it takes more time for catalase to catalyse the reaction below (fig 1.). It is expected that the time taken for oxygen to evolve will increase as the hydrogen peroxide becomes less concentrated (i.e. By increasing addition of water) (look at results table) ...read more.


This is to prevent any unwanted collisions, which may inadvertently speed up the rate of reaction. Results: (graph on graph paper) Hydrogen peroxide volume (ml) x-axis Water volume (ml) Time taken (seconds) 1st attempt A Time taken (seconds) 2nd attempt B Time taken (seconds) 3rd attempt C Mean avg. of A, B, C values (secs) Y-axis 20 0 280 306 300 295 15 5 385 570 522 492 10 10 720 752 808 760 5 15 947 964 1004 971 Conclusion: The prediction is correct, because the graph has a negative gradient, this means as hydrogen peroxide volume increases (therefore concentration) the time taken for 5ml of oxygen to evolve decreases, this clearly shown on my constructed graph. Note: time taken for 10ml of oxygen to evolve is indirectly proportional to rate of catalase. As time decreases, rate increases. This means catalase at a faster rate at higher concentrations of hydrogen peroxide and vice versa. If a graph of rate vs. concentration was constructed using this data, the graph would have a positive gradient. (Look at fig 2.) ...read more.


To stop the potato chips to dry out when I get to the experiment I could use cling film to cover them or not cutting them till the end. I could cut the potato pieces by using a electric ruler, it would virtually make every potato the same size, and it can go down to 4 decimal places. I could see the mass of each potato by weighing them so then each potato could be equal. Measuring the oxygen is a little harder; to measure oxygen there may be equipment that is not available to me, so this cannot be carried out. There were no anomalous results in this experiment. The results are reliable and sufficient enough to support the prediction. The method could be improved by stating certain reasons for doing certain actions e.g. peeling the potatoes, cleaning out the test tubes, etc. Doing some pre-liminary work, which would have been very helpful because then we could make better observations and predictions about this experiment, could have extended the investigation. We also could have done each concentration exercise each lesson, so we could spend more time on our method. I am quite pleased with the outcome of my exercise and the results. ...read more.

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