- Potato the pieces are cut from.
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The source of H2O2
- Delivery tube.
- Stop clock.
Preliminary Experiment
Apparatus
The apparatus I will use is: a scalpel, 6 pieces of potato, test tube, delivery tube and a stop clock.
Method
The apparatus will be set up as above and we will test which length of potato is the optimum size to time the reaction. The sizes will be 2cm through to 10cm with an incline of 2cm each time. We will then time how long it takes for the bubbles to move 5cm up the delivery tube.
Conclusion
From the preliminary experiment, it was found no addition safety measures where needed. The best size of potato was found to be 4cm as 10cm happened too fast to record and 2cm was too slow. So 4cm of potato will be tested with different concentrations of H2O2 and H2O, to see how the concentration affects the reaction.
Background Knowledge
Catalase is found in both plant and animal tissues. It is especially abundant in plant storage organs such as potatoes and the fleshy parts of fruits. Catalase is extremely important in cells because it prevents the accumulation of hydrogen peroxide. Hydrogen peroxide is a strong oxidizing agent, which tends to disrupt the delicate balance of cell chemistry. If too much hydrogen peroxide accumulates, it will kill the cell.
Several factors affect the action of enzymes: salt concentration, pH, temperature, enzyme poisons, radiation, the concentration of enzymes, and the concentration of the substance.
Catalase accelerates the breakdown of hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2).
The chemical equation for this reaction is:
2 H2O2 ----Catalase-------> 2H2O + O2
Prediction
I predict that the less diluted the H2O2 solution is the faster the bubbles will travel 5cm up the delivery tube.
Main Experiment
Apparatus
The apparatus used will be the same as the preliminary experiment.
Method
The apparatus was set up as before.
Then a 4cm piece of potato will be tested in a solution of 50ml of H2O2 and 0ml of H2O. This will continue till 0ml of H2O2 and 50ml of H2O changing it by 10ml each time.
Each reaction will be timed for the time it takes for the bubbles to move 5cm up the delivery tube.
Measurements:
Time will be measured in seconds.
Size of potato in cm.
The concentrations of the solutions in ml.
Conclusion
The graph shows that experiment number one reacted the fastest; we know experiment number one had the highest concentration of H2O2 and 0ml of H2O.
So this proves my hypothesis that the less diluted the solution was the faster the reaction, because there is no H2O dilution the solution.
Evaluation
All of the results fall into the same pattern; the less diluted the solution the quicker the reaction.
There where no anomalous results as such but on the graph experiment number 4 reacted 0.01 seconds faster than experiment number 3 but because of the closeness between the two times we could say it was down to human error, and the 0.01 is insignificant.
Inaccuracies in the experiment are cause by human error and the fact the test tube was not airtight. The experiment could be improved by using an air tight tube stopping some of the bubbles escaping.
