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Gcse Chemistry/Biology Joint Investigation the Decomposition of H2o2 Using Catalase In Yeast As a Catalyst

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Introduction

GCSE Chemistry/Biology Joint Investigation The Decomposition of H2O2 Using Catalase in Yeast as a Catalyst Planning Aim In this experiment I will investigate the effect of using a catalyst (enzyme), called catalase found in yeast, on the decomposition of H2O2. To measure the rate of this reaction I will collect the O2 given off when the yeast and H2O2 react. I will then see how temperature effects the reaction. Safety 1. Goggles will be worn at all times to prevent any splashes from irritating the eye. 2. Any spills will be cleared up straight away. 3. H2O2 is flammable so the substance will be kept away from naked flames. 4. The gas syringe will be placed in a clamp to prevent it being knocked over. 5. The gas syringe has a string attaching the two pieces together so that if the rear part of the gas syringe gets pushed out it will not fall on the floor and smash. Pre-tests We set up an experiment as shown in the diagram below. The diagram also shows the equipment we used. Pre-test Results First we tried 5cm� of H2O2 at 40�C for 3 minutes. We collected a result after every 30 seconds. The results were as follows: Time (sec) O2 Produced (cm�) ...read more.

Middle

This is correct about biological catalysts (enzymes) but not about manmade catalysts e.g. magnesium(iv)oxide which do not use the lock and key mechanism so do not become denatured. Results My Results are as follows: Time (sec) O2 Produced (cm�) 20�C 30�C 40�C 50�C 60�C 70�C 1st 2nd Av 1st 2nd Av 1st 2nd Av 1st 2nd Av 1st 2nd Av 1st 2nd Av 20 3 5 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 40 8 8 8 11 11 11 15 17 16 12 14 13 9 7 8 5 7 6 60 10 12 11 18 16 17 24 28 26 15 17 16 15 13 14 11 13 12 80 14 16 15 26 24 25 35 37 36 21 23 22 19 21 20 15 15 15 100 19 21 20 34 30 32 40 44 42 28 30 29 23 23 23 18 18 18 120 24 24 24 39 33 36 46 50 48 33 35 34 28 28 28 22 20 21 140 28 26 27 45 41 43 52 54 53 36 38 37 30 32 31 24 26 25 160 31 33 32 50 44 47 56 56 56 40 44 42 34 34 34 26 28 27 180 33 33 33 53 49 51 58 60 59 44 46 45 38 36 37 29 31 30 From this table I can make a graph: (see next sheet) ...read more.

Conclusion

The way to stop this from happening would be to shake the conical flask but this would add another variable and it would be very difficult to shake it the same each time. This would make the results less accurate. We could make it the same each time by putting the conical flask on a vibrating surface. These improvements would make a vast difference in the accuracy of the results. But there was another major problem to do with the heat of the hydrogen peroxide. As we only heated up the water bath we did not take into account the heat of the H2O2 to begin with. So when we thought we were using 70�C as our temperature, the temperature of the H2O2 was nothing like that high a temperature. The way to solve this problem would be to heat up both the hydrogen peroxide and the water bath and keep them both at a constant temperature. It was these things that led to some of my results being slightly off what I expected e.g. my 70�C results. I also think that I should have taken 3 sets of results instead of 2, as this would have drawn out any anomalous results more clearly. If I were to do the experiment again I would use all my improvements to make it a fairer and more accurate test. Richard McAlpine 10S ...read more.

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