In this experiment I am going to investigate the difference of oxygen that is given off between mushy potato and liver. When contained in a quantity of hydrogen peroxide.

Aim:

Background Information:

Catalyse is an enzyme found in food such as potato and liver. It is used for removing Hydrogen Peroxide from the cells. Catalyse speeds up the decomposition of Hydrogen Peroxide into water and oxygen. It is able to speed up the decomposition of Hydrogen Peroxide because of the shape of the Hydrogen Peroxide molecule. This type of reaction where a molecule is broken down into smaller pieces is called an anabolic reaction.

Catalyse

2H202 -→ 2H2O + O2

Hydrogen peroxide → water + oxygen (+heat)

Enzymes are proteins that act as catalysts. They are made in cells. A catalyst is something that speeds up a reaction, but does not get used up in the reaction. One can usually be used many times. An example of this is shown in the following diagram:

Prediction:

I predict, that if I have a higher enzyme concentration, then this will cause a higher rate of catalyse activity, because there will be more active places for a reaction to take place, which will cause more chemical reactions because of successful collisions because of the active site of the enzyme and substrate.

Apparatus

· Hydrogen peroxide (H₂O₂)

· Water (H₂O)

· Bung

· Conical flask x2

· Delivery tube

· Measuring cylinder 150ml

· Potato

· Stop watch

Diagram

Method

First of all, I will get all my equipment out and ready, as shown in the diagram, making ...

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Prediction:

Apparatus

· Hydrogen peroxide (H₂O₂)

· Water (H₂O)

· Bung

· Conical flask x2

· Delivery tube

· Measuring cylinder 150ml

· Potato

· Stop watch

Diagram

Method

First of all, I will get all my equipment out and ready, as shown in the diagram, making sure my work surface and apparatus are completely clean, and ready for the experiment.

Next, I will cut a potato into 6 equal (3 cm) cylinders, and keep them ready. Then, I will put 10cm2 of hydrogen peroxide into a conical flask, and immediately put the bung with the delivery tube in it on the conical flask, so oxygen does not escape. Then, I will put 150cm2 of water into the other conical flask. I will then take the bung off the conical flask with the H₂O₂ in it, put one of the 5 potatoes into the H₂O₂, and quickly put the bung back on, and put the other end of the delivery tube into the conical flask containing the H₂O. I will then immediately start the stop watch.

Then, I will count the number of bubbles that come through the delivery tube, and out of the water in a time limit of 5 minutes.

Then, I will do the experiment using 20 CM2 of H2O2, then 40, then 50, etc…

To keep it a fair test, I will do the experiment at room temperature. I will also measure out all the chemicals at eye level, and I will keep the amount of water used constant (150 cm2) throughout the whole experiment. The time will also be kept constant at 5 minutes for each experiment. The equipment must be cleaned and dried after each experiment to keep it a fair test.

Results

Conclusion

In conclusion, I have found that my prediction was correct. The higher the enzyme concentration was, the more oxygen was produced, or in the case of my experiment, more bubbles were produced.

This is because the higher the enzyme concentration, the more active sites there are where a collision between an enzyme and the substrate can take place.

As you can see in the graph, the amount of bubbles increases as the amount of enzyme concentration decreases. This indicates that it was reaching the optimum state of catalyse activity.

Evaluation

My experiment has gone quite well, but I could do certain things in order to get more accurate results. Firstly, if I had time, I would certainly do the experiment more times, as this would give me a more precise average.

Also, I would have done the experiment with a piece of liver too, just to make sure that the catalyse activity is the same in the liver as the potato. Although, I already know from what I have been taught, that the liver would give similar results to the potato.

Another thing I would have done is use a pureed potato instead of using a potato cylinder like I did. This is because it would give more active sites for a reaction to take place.

According to the graph, there are no visible outstanding results. However, if I had done the experiment more times and got a more precise average, then there may have been a few outstanding results. (By outstanding results I mean results that do not fit in with the other results, for example they may be too high or too low).