Prediction
I believe that as the amount of catalase added increases, more oxygen will be produced. This is because there is more catalase, so more particles can react at the same time, which will speed up the break down of the hydrogen peroxide and give off more oxygen in the set time period.
Safety/ fair test
To make the experiment safe I will wear safety goggles to protect my eyes from the hydrogen peroxide also all other lab safety rules must be obeyed. To make sure it is a fair test I will only change one variant which will be the amount of catalase (potato). I will also use the same apparatus for the initial experiment and the repeat. The potato will only make contact with the hydrogen peroxide when the stopwatch is started. I will try and measure the potato as accurately as possible using the scales provided.
Method
I will use;
- Conical flask
- Bung
- Rubber tube
- Burette
- Electronic scales
- Water basin
- Measuring cylinder
- Stopwatch
- Metal stand
- Clamp
I will then measure out 25 cm of hydrogen peroxide using the measuring cylinder and then pour the measured amount into a conical flask. Next I will measure out 1g of potato using the electric scales. Then I will fill the burette full of water and place it into the full water basin being careful so that no air gets into the burette. I will set the experiment up like this.
I will then drop the potato into the conical flask while at the same time inserting the bung into the conical flask. I will then measure the amount of oxygen being made in one minute by seeing how much water is being displaced by the oxygen travelling up the rubber tube and into the burette. When the one minute is up I will remove the bung from the conical flask so no more oxygen can get into the burette. I will then take the measurement from the burette buy seeing the total amount of water that has been displaced by the oxygen released. I will then wash out the equipment and do the experiment again but use 1g more of potato each time, stopping at 10g. There will also be a repeat of the experiment to make sure the test is fair. All measurements will be made accurately to ensure a fair test.
Results
The results I got from my experiments are listed below.
(Always 25cm of hydrogen peroxide used)
1st experiment
Repeat
I believe that these two anomalies are due to the scales not working properly for these two measurements. So the weight of potato may not have been correct.
Conclusion
My results show me that the more catalase that is added to the hydrogen peroxide, the more oxygen is produced. When 10g of potato was added the yield of oxygen was highest, with 1g of potato producing the least amount of oxygen. This shows that my predictions were correct. From the graphs below you can clearly see that the more catalase you ad the more oxygen is released, so this means there are more collisions happening in the reaction which backs up my prediction that the more catalase you add to a certain amount of hydrogen peroxide, the more oxygen will be given off.
1st experiment
Repeat
Evaluation
From my results I have found that generally the more catalase you add to a certain amount of hydrogen peroxide, the bigger the yield of oxygen. However there were two results in the repeat experiment that did not fit the general pattern, I believe that this is because during the repeat experiment when I was measuring out the mass of the potato the scales were not working accurately, but were changed for better scales for the rest of the experiment. I think that I could have improved my experiment by using only potato juice as the catalase is not in all of the potato, this would have affected the results. The experiments were carried out over two days in which the room temperatures were different; as temperature affects the rate of reaction this may have also affected the results. Also I used four different potatoes which could have affected the results because they may have contained different levels of catalase in the different potatoes. The scales I used for this experiment could have been more accurate as they only measured to one decimal place, this may also have affected the results slightly. I could also have done more repeats to make sure the results I was getting were accurate and consistent. The experiment could have been done the same accept for changing another variable like the concentration of hydrogen peroxide, the amount of hydrogen peroxide or the temperature at which the experiment was carried out at. Overall I think my experiment went well as it produced results which were similar to what I had predicted.
