I will also have to make sure that the amount of potato that I cut up is the same exactly otherwise it would not work i.e. exactly 5cm or something.
I would also have to make sure that exactly the same amount of Hydrogen peroxide is put in otherwise it will not be a fair test finally.
Finally I would have to make sure that the paste is the same consistency otherwise there could be more or less surface area against the hydrogen peroxide.
Safety
The safety is the same that it always is in a lab as follows:
1. Safety glasses or goggles are to be worn at all times when working in the lab, observing reactions, or preparing for a lab.
2. All accidents or spills must be reported immediately.
3. No food or drink is permitted in the laboratory area.
4. Nothing in the laboratory area should ever be tasted.
5. Laboratory areas should be kept clean and uncluttered.
6. Any spills or burns on the body should be flushed with water immediately and the teacher notified.
7. Always to tuck in your tie and take your jacket off.
8. Never sit down when using chemicals.
9.Never run around the lab and never leave bags in the aisle way.
Preliminary results
In my preliminary results I chose many variables to see which one would be to have a fair experiment. I would have to checked the following:
- How to have the potato.
- Amount of hydrogen peroxide.
- How long to time for.
The first thing I decided was that I should measure the amount of gas given off for 1cm-5cm of potato with a diameter of 1cm. I would first use the borer to get a cylinder of potato then measure the amounts of potato and cut them off. I decided not to mash the potato up, as it would not be possible to work out the surface area exposed to the hydrogen peroxide. I realised I would have to cut the skin off the end otherwise there would be less potato actually in contact with the hydrogen peroxide with the pieces at the end compared to the pieces in the middle.
I tried every amount of potato in the boiling tube and 20cm3 hydrogen peroxide was the best measurement as it covered all of the potato. I tried using 25cm3 but the foam that is given off when the potato reacts with the hydrogen peroxide goes up to the tube and starts going down into the measuring cylinder that is why I chose 20cm3.
The timing of the experiment was very important however it did not matter how long you timed it for as long as all the potato pieces where timed for exactly the same time. I chose to do 2 minutes as it shows a significant change between the amount of potato.
Hypothesis
I only have one real prediction for the experiment is the more surface area of potato in contact with the hydrogen peroxide the more gas would be given off. This happens because of peroxisomes in the potato. These are organelles inside the potato containing the catalyse. A catalyse is a chemical that speeds up the rate of reaction. This means that the more potato doesn’t actually make a difference to the amount of gas given off it just means it will happen quicker. So the real hypothesis is:
☺☺The more surface area of potato in contact with the hydrogen peroxide the quicker the rate of reaction☺☺
Results
To work out the surface area of a cylinder is worked out by using:
Surface Area of a Cylinder = 2 pi r 2 + s r h
The graph and the table of results show that the larger the amount of potato the more gas is given off in the 2 minutes.
Analysis
I have to change the table so it is easier to read:
This is a lot easier to see each length and SA compared to the average. This also shows that the amount of potato rises to the amount of gas given off. It also goes up quite consistently wit being just over the length of potato each time e.g. for 100mm of potato you get 139 cubic mm of gas given off.
Evaluation
The experiment has been very good, as it is exactly how I predicted it. There are only a few things that I would change if I did it again.
The first thing I would have to overcome would be the fact that when the cut potato is in the air it reacts with the oxygen. This would mean you would have to time from when the borer goes in until the hydrogen peroxide is added to the potato.
I would also have to change the method of adding the bung. As soon as the Hydrogen Peroxide gets added to the potato it starts reacting. This means that when you add the bung it will compress some of the air and blow it through into the measuring cylinder. So you would have to time how long till you put the bung in.
In conclusion I have found out that the catalyst should in fact make the reaction quicker but not actually make more gas be produced!
