To show the link, if any, between the rate of reaction of hydrogen peroxide and catalase and the surface area of the catalase source (potato).

AT1: HYDROGEN PEROXIDE AND CATALASE

Aim

Prediction

I am going to make 2 predictions on this experiment. The first prediction I am going to make is that the larger the surface area that the particles of hydrogen peroxide have to work on the larger the reaction. The second prediction that I am going to make is that if I double the surface of the catalase source then the reaction will double or if I triple the surface area of the catalase source then the reaction will triple. I have found out that potato is a strong source of catalase and therefore I will use potato as my catalase source in this experiment.

If you have a 1 cm3 piece of potato then you have 6 cm2 of surface area on which the reactant can react with, but if you cut this into 2 even pieces then you will have an extra 2 cm2 area on which the reactant can react, giving you a total of 8 cm2 surface area. So long as all the surface area is covered with hydrogen peroxide then all the surface area will react, so if you have 6 cm2 and 8 cm2 pieces of potato the 8 cm2 area will have more reactions causing a higher reaction rate.

If you have a piece of potato with a surface area of 6 cm2 and cut it into even parts so as that it has 12 cm2 then you will have twice the reaction, this is because you have twice the surface area for the hydrogen peroxide to work on, and so long as there is enough hydrogen peroxide to completely cover the potato this theory will work. This is called the collision theory. This states that ‘if 1 of the reactants is a solid then breaking it up into smaller pieces will increase its surface area. This means the ...

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Apparatus

1 X Potato

500ml Hydrogen Peroxide

Scalpel

Ruler

5 X Boiling tube

Stop Clock

Cutting Tile

Measuring Cylinder

Safety

Before you start the experiment I must draw your attention to safety aspects within this experiment.

Always wear goggles while handling the hydrogen peroxide.
Always lift and hold a bottle by the neck and base
Keep cap on bottles when not in use
Check hands for cuts before starting experiment and cover any that you may find
Be careful whilst using the scalpel
Wash hands thoroughly after experiment

Method

Take the potato and place on the tile. Cut 15 even 1 cm3 cubes out of the potato. You will need to use your ruler and scalpel.
Put 1 of the potato cubes into a Boiling tube. Now cut 1 of the cubes in half and place the pieces in different tube. Now cut 1 of the cubes into quarters and place pieces in a different tube. Now cut 1 of the cubes into eights and place pieces in a different tube. Now cut the last cube into sixteenths and place pieces into a different tube.
Measure out 60 ml of Hydrogen Peroxide with the measuring cylinder and pour into the first boiling tube. Now start the stop clock straight away making sure that all the potato is submerged. Time for 1 min 30 sec and then measure the height of the froth (oxygen bubbles) produced in the tube and record result.
Repeat step 3 with all off the tubes.
Repeat steps 1 to 4 twice more

Results

Conclusion

As my results show the predictions I made were correct. My predictions were as follows: the larger the surface area the faster the reaction AND if you double the surface area then you double the rate of reaction. I will conclude my first prediction first. I predicted that the larger the surface area then the faster the reaction would be. I have proved this prediction with my results. When I reacted potato with a surface area of 14 cm2 with Hydrogen Peroxide there was a much faster reaction compared to when I reacted 6 cm2 of potato with Hydrogen Peroxide.

My second prediction was that if I double the potatoes surface area then I would double the reaction thus doubling the froth produced. When I reacted 6 cm2 potato with Hydrogen Peroxide it produced 4.3 mm of froth and when I reacted twice the surface area (12 cm2) it produced 9.3 mm of froth which is over double but not by much which I think proves my second prediction.

Evaluation

As my graph shows my results back up my predictions quite well. I first predicted that the larger the surface area of potato the faster the reaction would be, if you look at my graph at surface area of 6 cm2 and 14cm2 you will see that the larger the surface area the faster the reaction, I also predicted that if you double the surface area of the potato then you will double the rate of the reaction and if you look at my graph at the surface areas of 6cm2 and 12cm2 then you will see that my results are only slightly out and I think that this is sufficient proof for my second prediction.

I did not get any anomalous results although my line of best fit did not include all my points, which means that my experiment was inaccurate in certain aspects. If you use a test tube to carry out the experiment that is not thoroughly clean then this may and probably affect your results and as I did not clean my test tubes before starting this may have played a part in the alterations of my results.

During this experiment there were many variables which could have been controlled and changed to alter the experiment. During my experiment I did not control factors such as light intensity and temperature which could have exposed my results to change to get better results in my experiment I could have changed a different variable which would have given me more results to work with.

There were many ways in which I could have extended my experiment as I briefly mentioned above. I could have repeated this experiment several times to receive a better average or used more surface areas to compare more results.

Overall I think my experiment went quite well.