Prediction
I predict that the potato chip in the distilled water will expand due to turgidity. I think the potato chip in the weak sucrose will change very little as the water levels are both balanced. I think that the potato chip in strong sucrose will decrease in size, as there is more water inside than outside so plasmolysis will occur.
My Results
Evaluation
When I did the experiment I measured the length of the potato chips and worked out the difference in length after 20 minutes. I then used those results to workout the average percentage length change. However I did not find that the results were accurate or easy to obtain accurately using this method. Also looking at my results I can see that there are a number of significant differences between test 1 and 2. this means that my average lengthchange is more thanlikely to be inaccurate. This is why I have not analysed my set of results as I feel that they are misleading due to the nature in which I carried out the experiment. They are not accurate enough to tell me anything specific. I faced many difficulties throughout the experiments. Although it was fairly easy to get the same diameter for each potato chip, as I used a borer to obtain this, I found it difficult to cut each potato chip to the same length accurately. I also did not feel that this particular method was accurate. When it came to find a change in length, my results were rather inaccurate, even though they did fit with my prediction. I found that there was very little length change. There was, however a change. This made me think that if the length has changed, will the width not have been altered also? I also think that there will have been a number of changes that were too small for me to measure using a ruler. I was unable to measure any of these things though using my method. Overall I feel that this method of measurement is not accurate enough. Therefore I will be doing further investigations so as to find the most accurate way of measuring the change in the potato chip.
Preliminary Experiment 2
As I felt that after my last experiment I needed to review my method I am going to carry out a second preliminary experiment. In this experiment I will use a slightly different method that I think will be more accurate. The reason for doing this is to check that my thoughts on what to change are correct. This experiment should show up any further difficulties I may come across. I should be able to make my final experiment fairer and more accurate after this.
Method
Changes to Method
In this experiment I will still measure the length of my potato chip but this time I will also measure the mass change. I measure this using a pair of electronic scales. This time I will also blot the potato chips after removing them from the solution they are in.
EQUIPMENT:
- Borer
- Chopping board
- Blade
- Stopwatch
- Potatoes
- Ruler
- Results table
- Distilled water
- Sucrose solution
- Labels
- Burettes
- 6 test tubes
- Test tube rack
- Electronic scales
- Tissue
WHAT I WILL DO:
I will use a borer to cut out 6 cylinder shaped pieces of potato chip. I will then use a ruler and a scalpel to cut each piece to the same size. After that I will measure the mass of each potato chip on the electronic scales. Then I will put 6 test tubes in a rack. The reason I will use 6 is that I am going to use 3 different concentrations of solution but do 2 tests of each. I will then put a strong sucrose solution in 2, a weak sucrose solution in another 2 and distilled water in the last 2. Then using the labels I will write on each of the test tubes what the solution strength is and also the length of the potato chip that will be put in it. I will then make sure the stopwatch is ready to start. Once all this is complete I will put a potato chip into each test tube of solution and time it for 20-30 minutes. After the allocated time is over I will remove each potato chip from its test tube and blot the surface of each one using a tissue. I will then once again measure their lengths and masses so as to see if there has been a change. I will then fill in my results table.
Prediction
I predict that the potato chip in the distilled water will expand and the mass increase due to turgidity. I think the potato chip in the weak sucrose will change very little as the water levels are both balanced. I think that the potato chip in strong sucrose will decrease in size and mass, as there is more water inside than outside so plasmolysis will occur.
My Results