Catalase Investigation

Prediction:

I think that as the concentration of hydrogen peroxide is increased the height of froth will increase. I think this because there will be more hydrogen peroxide molecules for the catalase to collide with so the time between the products being ejected and a new substrate entering the active site will decrease. So the process will speed up because there will be a shorter period where the enzyme is not doing anything. I think that the difference in time taken will be large between the smallest and the biggest concentration I use. I think that the time taken to collect the hydrogen is going to be proportional to the concentration of the hydrogen peroxide.

Therefore as the concentration decreases I think that the height of froth will decrease. So the hydrogen peroxide is no longer what is stopping the rate from increasing e.g. the concentration of catalase.

Variables:

Surface area: Because if the surface area is greater that means more hydrogen peroxide molecules can collide with the exposed catalase. This means that more hydrogen peroxide will be decomposed and the rate will increase.

Temperature: Enzymes have an optimum temperature that they function best at, if the temperature increase over this temperature then they begin to become denatured. As you increase the temperature towards the optimum temperature the enzymes become more active. So temperature could affect the investigation because if the temperature is changed the enzymes will work at a different rate.

Concentration of catalase: The higher the concentration of catalase the more hydrogen peroxide that can be broken down at once. This will increase the rate of the test.

Concentration of substrate: If you increase the amount of hydrogen peroxide then the time it takes for the catalase to collide with it is decreased so the catalase works more efficiently. This would increase the amount of hydrogen gas so the 10cm³ would be collected quicker.

This is the variable that I am going to change. I am going to do this by diluting the hydrogen peroxide with water.

Variables I will keep constant:

I am going to keep concentration of catalase, temperature and surface area the same. I am not going to change these variables in order to keep the test fair otherwise I wouldn't know which variable it was that caused the rate of reaction to change.

Apparatus:

Boiling tube rack

Boiling tube x 6

Hydrogen peroxide

Water

Ruler

Diagram:

Method:

. Set up apparatus as shown in diagram.

2. Place 3cm³ of liver puree in each test tube and record the height of froth in a table.

3. Repeat experiment at least 4 times the results are reliable as we can average them and so it is possible to plot a decent graph.

4. Remember to be safe while doing this experiment by wearing safety specs because Hydrogen peroxide is harmful.

Results:

Tube

H2O/cm³

H2O2/cm³

Height of froth repeated 4 times

Average Height of froth/mm

0

5

87.5

2

4

69.5

3

2

3

35.25

4

3

2

2.75

5

4

4.5

6

5

0

0

Analysis:

The investigation was successful in changing the height of froth produced after adding increasing concentrations of hydrogen peroxide. This is easily seen in my results that the height of froth increases as concentration of Hydrogen Peroxide, for example; When the amount of hydrogen peroxide is 1 the height of froth is 4.5 mm, when the amount of hydrogen peroxide is 3 the height of froth is 35.25mm, and lastly when the amount of hydrogen peroxide is 5 the height of froth is 87.5mm so there is a definite increase of froth from the bigger increase in ratio to the smallest increases. This is also noticeable in my graph, which shows a steady increase in height of froth although perhaps slightly quicker towards the higher concentrations. The results are very similar to my prediction. These results show that that with added concentrations of Hydrogen peroxide the greater the height of froth. This is what I predicted to happen in this experiment.

Conclusion:

This investigation has shown that as the concentration of Hydrogen Peroxide gets greater the height of froth produced increases as well. This is because of enzymes. All living cells contain Catalase which are biological enzymes. All living cells some energy releasing reactions and they produce Hydrogen Peroxide, which is fatal to cells. Catalase breaks down Hydrogen peroxide to Water and oxygen. The concentration of Hydrogen peroxide affects the height of froth because there are greater numbers of Hydrogen Peroxide molecules which increases the chance of a successful collision with the Catalase. When a successful collision occurs a reaction takes place with turns Hydrogen Peroxide into Water and Oxygen.

Evaluation:

This investigation was a success and easy to perform and the results collected clearly show an increase in height of froth when the concentration of Hydrogen Peroxide is increased. During the experiment I found that measuring the height of froth slightly harder than expected mainly because of the test-tube rack. I found that I had to either remove the test-tube from the rack to measure it, which meant the froth had time to disperse or I had to measure the height a few centimetres away from the test-tube, meaning if I did not look straight on in front of the test-tube and ruler it could give the illusion of being lower or higher froth than it actually was. Another problem is that glass is well known to distort light and therefore any measurements I was taking may not have been accurate because the froth could be at a different height than it appears. There doesn't appear to be an anomalous result on my graph. I know this because my line of best fit roughly goes through all of the points.