Hydrogen peroxide (2H O ) is formed of many cells and is very toxic. It threfore needs breaking down quickly, so the enzyme catalase is very important.
Whilste the experiment is being conducted some errors may occur that could effect the final results. One possible effector is the heat/temperature. I know that, in the reaction of the enzyme catalase with hydrogen peroxide, the rate of reaction should double with every 10 degrees Celsius increase in temperature. I know that when conducting my experiment, the change in temperature will not be as high as 10 degrees Celsius, but it may cause a slight effect. The kinetic theory explains why the rate of chemical reactions will increase with temperature. As the temperature increases the movement of reactant molecules also increases leading to more collisions which result in reactions. I also know that a general is known, ‘rule of thumb,’ which suggests that the rate of a reaction doubles for each 10 degree Celsius rise in temperature. This has also been shown to be true of reaction catalysed by enzymes when other conditions, such as concentration of enzyme and substrate, are constant but it is important to remember that this will only occur between approximately 4 degrees and 50 degrees Celsius.
Prediction :
I believe that the rate of production of O and H O will increase, with substrate concentration. This rate is most probably proportional, until the saturation point is reached. After the saturation point has been reached I believe that adding extra substrate will make no difference.
I also think that the more substrate that is being used, the more enzyme will be used, so therefore the amount of O that will be given off will be higher.
The rate will steadily increase when more substrate is added, this is because there will be more molecules of the enzyme that are being used which will therefore result in more reactions so the amount of oxygen is produced more rapidly.
Apparatus :
* Bung * Hydrogen Peroxide :
* Conical Flask Variations of Concentrations:
* Large Bowl ¾ filled with water - 100%
* Spatula - 80%
* Stop Watch - 50%
* Test Tube - 40%
* Tubing - 20%
* Weighing Scales * Yeast
Plan/Method :
- Set up the apparatus, according to the diagram above.
- Using a spatula, weigh 0.2g of yeast (ensuring care is taken to ensure exact amount) and put it into the conical flask.
- Measure out 4ml of hydrogen peroxide (2H O ) (concentration 100%).
4. Once measured correctly, ensuring correct amount, pour the hydrogen peroxide (substance) into the conical flask containing the yeast and immediately cover up the conical flask by putting the bung into the top of the conical flask, at the same time start the stopwatch.
- Bubbles should start to appear in the conical flask, and the water in the test tube start to decrease. Once the water has gone from the test tube stop the stopwatch immediately and record the time.
- Repeat this experiment using a concentration of 100% three more times so that an average can be obtained.
- Repeat the experiment, exactly the same, but using hydrogen peroxide concentrations of 80%, 50%, 40% and 20%.
7..As with the 100% concentration, repeat all the tests at three more times so that an average can be obtained. Repeating the experiments several times will help to produce better and more accurate results.
Results:
(Results table)
The times above are in minutes/seconds. The average times that I have worked out for each concentration are showed in the far right-hand column, I have worked them out to two decimal place.
From the results I have found above I was able to plot various graphs of the rate of reaction against the concentration of Hydrogen Peroxide.