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The Rate of Decomposition of Hydrogen Peroxide with Catalase.

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Introduction

The Rate of Decomposition of Hydrogen Peroxide with Catalase -PLANNING- Introduction Catalase is a biological catalyst or enzyme. It is made up of protein molecules which are found in living cells. Enzymes speed up reactions in the body. Catalase is found in potatoes and liver and is the enzyme used to speed up the decomposition of Hydrogen Peroxide in the human body. Hydrogen Peroxide is also found in the human body however it is toxic to human cells, lipids, DNA and protein. It is a bi-product of metabolism. Examples of the reaction which produce Hydrogen Peroxide are amino acids being converted into fuel and lipids being converted into carbohydrates. Hydrogen Peroxide decomposes naturally, but slowly. The products of this are Water and Oxygen. The chemical formula for Hydrogen Peroxide is H2O2. An enzyme works if it has the same shape active site as that of the substance it is reacting with (substrate). The reaction or decomposition then occurs in the active site and the products leave. Human Enzymes are destroyed above temperature of 37 degrees C by their active sites being altered and no-longer fitting the shape of their substrate. Enzymes are never used up in a reaction so can continue to react with more substrates after one reaction. ...read more.

Middle

Timer - With minutes and seconds - Split seconds cannot be accurately used when forming a conclusion from results. Yeast solution Hydrogen Peroxide Distilled Water Right Armed test tube Diagram Method > Set up the apparatus as in the diagram > Measure out the concentration of yeast solution to 1ml with the 1ml syringe i.e (0.8ml yeast, 0.2ml distilled water for 80%. 0.6ml, 0.4ml distilled water for 60%. Etc.) > Place the 1ml solution into the test tube and then replace the bung. > Measure out 2ml of hydrogen peroxide with the 5ml syringe and place in the bung. > Start the timer when the hydrogen peroxide hits the yeast solution. > When the 20cm3 syringe gets to the 10cm3 mark stop the timer and record the result. > Repeat this for each percentage - 20%, 40%, 60%, 80%, and 100%. > Repeat all of these 3 times. Safety The hydrogen peroxide needs to be treated with care in the experiment as it can bleach skin and clothing. Therefore eye protection should be worn and loose garments taken off. Fair Test/ Accuracy To ensure that it is a fair test the temperature of the water bath will be monitored throughout the experiment if it changes +/- 0.5 then it will be brought back up/down. ...read more.

Conclusion

So with a 100% concentration catalyst - Catalase and a 100% concentration substance - Hydrogen Peroxide, the time taken for the Hydrogen Peroxide catalysing and decomposing is twice the time taken for Hydrogen Peroxide at 100% catalysing with Catalase at 50%; This is because there is another substance involved in the collisions - water. This is shown more clearly in the diagrams below: The conclusion has supported the prediction. As the conclusion shows that as the concentration goes up the rate and time taken for the decomposition of Hydrogen Peroxide will also go up. The conclusion also shows the quantative prediction to be true. That as the concentration of the Catalase doubles the time taken for the decomposition will halve. This is shown by the exponential curve on the graph. Rate has also been shown to be directly proportional to the concentration of Catalase by the straight line on the rate/concentration graph. My prediction was correct because the experiment uses the collision theory and how reaction time is affected by concentration. - Evaluation - The procedure used was adequate in getting the results found although if more time has been given the accuracy of results may have been better. There were a few anomalies found in this experiment Alex Oakes 11Rd Biology Sc1 Coursework Set 11J1 19/11/2002 5:40 PM Page 1 of 9 ...read more.

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