To find out the effects of changing the surface area of a potato chip has on the rate of reaction between catalase and hydrogen peroxide.

        

We used this factor for our preliminary test to determine which temperature to use in our experiment, as it would affect the results. We set up 5 test tubes with potato and hydrogen peroxide and kept them in the chosen temperatures. We measured the height of foam in cm. Obviously the temperature with the highest foam height worked the best at that temperature.

Preliminary Test results

The reaction worked best at room temperature, producing the biggest height of foam. This is the temperature we will use in our main experiment. This will need to be controlled for the experiment to be a fair test otherwise the enzymes will gain kinetic energy and the rate would increase. To make sure the solution of catalase (in potatoes) and hydrogen peroxide will remain in a test tube at room temperature that will remain constant throughout the experiment.

The concentration of the enzyme catalase will increase the rate of reaction, the overall gas given off will not be affected but the time taken will be quicker if the concentration is increased. This is due to the increase of enzymes in the same amount of volume and therefore the more active sites available, the quicker the substrate (hydrogen peroxide) can be broken down.

The surface area of the potato would affect the experiment due to the increase of catalase on the outside of the potato for the hydrogen peroxide to react with. As the catalase is contained within the cells, the more cells that are exposed to the hydrogen peroxide, the more enzymes there are to react with. The number of active sites increases and this increases the number of enzyme substrate complexes, which then release more hydrogen. This is the factor we are going to use in our experiment and change the length of the potato chip with the width remaining the same.

Equipment List:

• 5 test tubes
• Test tube rack
• Knife
• Potato chips (width and depth of 1cm)
• Measuring cylinder
• Hydrogen peroxide 6% concentration
• Goggles
• Stopwatch
• Delivery tube
• Tub full of water
• Measuring cylinder

Method:

1. Set up the equipment as in the diagram above.
2. Cut up 5 strips of potato, one strip 1cm long, one strip 2cm long etc. (All strips have a width of 1cm) then place each strip into a tube.
3. Measure out 5cm cubed of hydrogen peroxide into the measuring cylinder, pour it into the tube with the strip 1cm long and put the stopper on top of the test tube with the delivery tube attached to the beaker full of water.
4. Every 30 seconds see how much hydrogen has been released by looking at the measuring cylinder in the water.
5. Repeat these steps for each length of the potato chip.

Prediction:

I predict that the bigger the surface area of the potato chip, the quicker the rate of reaction will be. This is due to the increase of catalase on the surface area of the potato, which means that there are more active sites for the hydrogen peroxide to react with. For example a piece of potato with a surface of 2cm squared would have double the more catalase covering its surface than a piece 1cm squared. So, if there is more catalase that results in more active sites available for the substrates.

        The maximum length we are using is 5cm, which has a surface area of 22cm, squared and I predict this will produce the most hydrogen gas, however if we were to use bigger pieces I think the rate would still continue to increase.

Results

Average Set (used for graph)

Conclusion of Results

On the graph, the potato chip with the largest surface area had the greater gradient.