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What is the effect of concentration of H2O2 on the rate of catalase activity?

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What is the effect of concentration of H2O2 on the rate of catalase activity? Aim: - This is an experiment to examine how the concentration of the substrate hydrogen peroxide (H2O2) affects the rate of reaction of the enzyme catalase. Preliminary: - Enzymes such as catalase are proteins. They are specific to a certain shape and are used to speed up a certain reaction. They do not run out for they are not used up. Catalase is a catalyst. Catalase is an enzyme found in food such as potato and liver. It is manufactured by cells to break down H2O2 (hydrogen peroxide) a poisonous bi-product of metabolism. Catalase speeds up the decomposition of hydrogen peroxide into water and oxygen as shown in the equation below. catalase 2H2O2 ???? 2 H2O + O2 hydrogen water oxygen peroxide It is able to speed up the decomposition of hydrogen peroxide because the shape of its active site matches the shape of the hydrogen peroxide molecule. This type of reaction where a molecule is broken down into smaller pieces is called a catabolic reaction. ...read more.


3. Immerse the thistle funnel into the beaker with the steam below the surface of the hydrogen peroxide over the funnel stem. 4. Measure the volume of oxygen evolved in a time of 5mins. 5. Repeat the procedure with the other hydrogen peroxide solutions. Take care not to contaminate any solution with another, as this would cause inaccurate results. 6. Repeat all the tests at least three times (time dependent) so that an average can be obtained. Note all the results in a table such as the one below. Concentration of H2O2 (g/cm3) Amount of oxygen produced (cm3) Average (cm3) 25 2.00 2.03 2.02 2.02 20 1.84 1.86 1.86 1.85 15 1.46 1.50 1.47 1.48 10 1.11 1.13 1.11 1.12 5 1.00 0.80 0.90 0.90 This gives the rate in cm3 of oxygen produced in the time of 5 minutes, this is because I am timing how much oxygen gas is given off in the space of 5 minutes for the various concentrations of hydrogen peroxide. From these results, a graph can be plotted with concentration on the x-axis and the volume of gas released on the y-axis. ...read more.


the same. However, unfortunately, in practice it was impossible with this basic apparatus I had to keep all measurements precisely the same. For example: 1. There is a slight delay between pouring the thistle funnel into the beaker of hydrogen peroxide. This will slightly affect all the results for each individual experiment but as I carried out all the steps in the same way, it should not make any negotiable difference to the overall result. 2. It is also impossible to precisely measure out the amounts of hydrogen peroxide and distilled water each time. As the scale on the measuring cylinder shows the measurement to the nearest 1mm3, the solutions that I used should be correct to the nearest mm3. Criticisms & ways to improve experiment. I used catalase found in potatoes, which made amount was hard to measure, however, measuring the amount of potato wasn�t difficult. However, that piece could contain different amounts of catalase compared to another piece. The results from both pieces would be negotiable. Maybe having a source of catalase from yeast would have been much easier to use and handle. Specific amounts could be measured much more precisely. James Trebilco ...read more.

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