I will make it a fair test by - Having all the measurements the same for each of the trials and by keeping the H2O2 at the same temperature.
I will make the experiment reliable by - Repeating the experiment three times, therefore having three trials giving us more accurate results and by following the Variables ‘instructions’.
Safety
- Goggles- to protect your eyes from Hydrogen peroxide( H2O2)
- Apron- to protect your clothes from Hydrogen peroxide (H2O2)
- Sharpe knifes- be careful and safe when handling them and always cut on the white tile.
- Corer- be careful and safe when using the corer as it is sharp.
Variables
Results table (empty)
Hypothesis
I predict that by increasing the surface area of the substrate the amount of oxygen produced will increase, which shows the enzyme is
breaking down the hydrogen peroxide faster.
As the surfaces are increased the catalase reaction will speed up, therefore more oxygen is released in the time allocated.
As the surface area increases, the speed of the reaction will increase therefore the gas will be produced faster, this is because most chemical reactions happen faster when there is more of the reactant to react with.
Hypothesis Graph
Using the apparatus safely and equipment properly
While working all safety procedures were followed very carefully like the use of safety goggles and the careful use of knifes. I feel the measurements we took were fairly accurate as the results were very close to what we were expecting. The stopwatch was accurate to the nearest millisecond. We were not able to measure this accurately however so our time was accurate to the nearest second.
Results table
Analysing
From my graph I have found generally, that as the surface area increases the volume of hydrogen peroxide increases too. Also, the volume of oxygen that was produced formed a positive correlation. For each piece of avocado, the graph shows that the oxygen produced increased fairly slowly and unevenly, they were not gradient results, as shown on the right→.
For example I would have hoped that as the surface area increased (doubled) the volume of oxygen would have doubled, for example shown on the right→.
The range was 9.66˙ml to 20.33˙ml, which shows that the oxygen level only increased by 10.67ml (20.33˙ – 9.66˙ = 10.67). There was one obvious anomalous result which was 16.33˙and probably due to the dent in the avocado, it is only 0.67ml more than the one before, which was 15.66 (16.33˙ – 15.66˙ = 0.67), whereas the other results are 3 to 4ml more than each other.
3ml Difference 3ml Difference 0.67ml Difference 4ml Difference
Anomalous result
Calculations ↑
As you can see from the calculations above, a pattern is revealed, 3ml difference, 3ml difference, anomalous result (due to dent in avocado), and 4ml difference. If the experiment was carried out more carefully (for example looking closely at the temperature of the hydrogen peroxide etc) then the pattern would have continued to be a 3ml difference, therefore our results would have been more accurate.
The average result for piece one was 9.66˙ml which proved to be the smallest amount of the oxygen produced and the smallest surface area, 1178mm.
The average result for piece five was 20.33˙ml which proved to be the biggest amount of the oxygen produced and the biggest surface area, 2748.4mm.
Comparing my results to my prediction
My results correspond with my original prediction. The graph however, does not correspond exactly but that was not to be expected and was probably due to the experiment not being carried out with extreme precision.
From my results it can be proved that as the surface area increases the amount of oxygen produced increases too.
Evaluation
I think the investigation was carried out well as the results recorded were roughly what we predicted and safety procedures were followed carefully so no accidents took place and no people were injured. If we were to do it again we would use the same avocado for each trial to give us more reliable results. The experiment was fairly easy to carry out. The aspects of the method I found most difficult to carry out was measuring the avocado lengths and managing to plug the bung in the conical flask as soon as the avocado hit the hydrogen peroxide. This proved difficult but I think we managed it well. We tried our hardest to carry out the experiment with great accuracy. Although we tried to carry out the investigation accurately the results did not seem to be as reliable as we had hoped.
An anomaly was found in our results which might suggest our experiment needed to be carried out more carefully with a higher level of precision.
This could be done by doing four trials (taking four sets of results) instead of three. This should give us the averages to a higher degree of accuracy. To give us a more accurate pattern (like the one stated above) we could repeat the experiment that did not fit the pattern again, therefore giving us accurate results that fir the pattern. To give us more precise results we could have taken more readings, for example instead of recording the volume every 120 seconds we could have recorded the volume of oxygen every 180 seconds, this would therefore improve the accuracy of our graph which would lead to us having a more distinct and obvious pattern.
The method could have been improved by using the same avocado for all three of the trials this would have made sure all the readings were accurate and precise. By doing this we could make the experiment more of a fair test.
I feel the evidence is of a sufficient accuracy to support the conclusion, but I do not feel we had enough roar data to find out what happens to the volume of oxygen after the reaction has slowed down this could be found out however by collecting more data. I predict that if we did collect more data the results would then drop and decrease as the reaction slowed down to a stop.
The results we recorded were what we expected apart from the anomalous result because the volume of oxygen only increased by 0.67ml. This could be solved though, by repeating that experiment again to give a more accurate result. The prediction however is still quite accurately followed by the results.
If we were to do the investigation again we would probably look at altering another variable, for example the temperature of the hydrogen peroxide. This would give us extra patterns, similarities and gradient data to look for in the results.
