Method:
- Grate 5g potato. This will increase the surface area and also break open the cells to release the enzyme Catalase.
- Put the tissue into a conical flask.
- Secure the top of the flask with a bung attached to a delivery tube
- Place the other end of the delivery tube into a tank of water. Place over it a measuring cylinder filled with water
- Measure 5cm3 hydrogen peroxide into a syringe. Place this into a hole in the bung of the flask.
- At room temperature, add the hydrogen peroxide to the potato and immediately start the stop clock.
- Shake the comical flask every 5 seconds to ensure that the reactions mix well.
- Record the volume of oxygen produced by displacing water in the measuring cylinder, after three minutes, RECORD THE RESULTS.
- Repeat this procedure at a range of temperatures
- Obtain these temperatures by:
0 C – placing the tissue + H2O2 in ICE.
40 C - Placing the tissue + H2O2
60 C - Placing the tissue + H2O2 + in a water bath.
80 C - Placing the tissue + H2O2 in a water bath
Apparatus:
- 5g potato
- Knife
- Grater
- White tile
- Comical flask
- Delivery tube + bung with 2 holes
- 100cm3 measuring cylinder
- Glass tank
- Stop clock
- Crushed ice
- Water bath
- Thermometers
- Electronic balance
Fair test:
To make it a fair test I had to……
- Make sure the potato was from the same batch.
- Same amount of potato is used
- Same volume of hydrogen peroxide used
- Time taken for reaction between potato and hydrogen peroxide
- Time taken to leave reactants at each temperature before mixing them
Prediction:
I predict that this experiment will be a success. I think that the most successful temperature was between 40 c and 50 c.
If I used liver instead of potato, it would be more effective, liver has more enzymes, which reacts better with hydrogen peroxide. By success I mean that the most oxygen will be produced at 40-50 c.
Safety precautions:
- Hydrogen peroxide is corrosive and can harm skin. Wash with water.
- Wash your hands after using liver/potato.
- Use sharp knives properly for cutting liver.
- Used goggle when using Hydrogen Peroxide
Use boiling water with care
Results:
Conclusion:
At 0 degrees a high volume of oxygen was produced. This is because there is a lot of heat energy, therefore the molecules collide and react. At room temperature, les energy was produced. This is because there is less heat energy therefore molecules cant move about which means there are less collisions between enzyme and substrate reactions.
At 40 degrees, the greatest volume of oxygen was given off, this is because lots of heat energy therefore lots of kinetic energy therefore the catalyst and hydrogen peroxide molecules collide more therefore more reactions take place and more oxygen is produced.
At the higher temperature (60 and 80 degrees). The volume of oxygen produced declines, this is because enzyme molecules begin to denature. This means that the active site of the molecules is put out of shape therefore cant react with hydrogen peroxide and no oxygen is given off.
Evaluation:
I found that my results had anomalies in experiment 1 at temperature 50 c3 and in experiment 2 at temperature 12 c3. This may have been due to errors in the method/procedure. For instance I left the catalyst and hydrogen peroxide at each temperature for 5 minutes to used to the temperature. Other reasons for anomalies could be because I measured the enzyme incorrectly or the potato was to old by the second experiment.
There were some problems with carrying out the experiment, they were that the baths were unreliable, it was hard to get them to the correct temperature. If I could do this experiment again I would improve it by doing the measurements correctly and following the procedure.
