The length of each cylindrical potato tube. I will measure each potato chip to ensure that; they are two cm long, by using a ruler. If the length of each chip is not the same then, there would be more water inside some of the potato chips then others. Therefore the results would not be fair.
The diameter of each potato chip. I will use the same cord borer to cut
the potato chip out from the potato, to ensure that each potato chip has the same diameter. If the diameter of one of the potato chips is larger than the others the, then there would be more change. As there would be more water inside that potato chip than the others.
The texture of the cylindrical potato tube. I will ensure that the texture of each potato chip is the same by, using the same white potato. For all three of the potato chips.
The time and duration of the experiment. This will mean that all three of the cylindrical potato tubes, stay in the sucrose solution for the same amount of time. If they do not stay inside the sucrose solution for the same amount of time, there would be more change in the one that is left inside the longest. This is because it was left in the solution longer than any other.
I am also going to use the same balance to weigh my potato chips. This is because the measurements may slightly vary between scales.
Prediction
I predict that the lower the concentration of the sugar solution in the test tube the larger the mass of the potato will be. This is because the water molecules pass from a high concentration, the water, to a low concentration, in the potato chip. Therefore, the chips in higher water concentrations will have a larger mass than in higher sugar concentrations.
Equipment
In order for me to do this experiment, I will need the following equipment:
- Different concentrations of sucrose solution
Before I do my final experiment, I will have to do some preliminary work first. For my coursework I have to do preliminary work because, the concentration of the sucrose needs to be very precise, in order to get accurate results. However I have a large range of sucrose solutions, from 1% sucrose to 80%. This is too large. So therefore I need to narrow down my range of solutions first, before I do my actual experiment. I will do this by using five solutions, covering a wide range: 10%, 20%, 30%, 40% and 50%. From this I will then I will look for the solution that causes the least change, in the mass of the potato. Having discovered this, I will then be able to use a new range either side of that particular percentage, for my real experiment.
Method
To do my preliminary experiment I will use the following step by step method:
Step 1 - First, I obtained all the apparatus I required, to do my preliminary experiment.
Step 2 - Then, I used a cork borer, to cut three cylindrical potato tubes from the fresh white potato. When cutting the cylindrical tube, I ensured that each was two centimetres long.
Step 3 - Having done this, I placed five test tubes in the test tube rack and added a different percentage of sucrose solution from my range, in each test tube.
Step 4 - Finally having added the solutions into the test tubes, I added one cylindrical potato tube in each test tube. Before placing the cylindrical potato tubes, I ensured that the mass of each was 2.5 grams. I also placed the potato tubes in the test tubes at the same time. So that they would stay in the solutions for the same period.
After completing my preliminary experiment I produced the following results:
From my preliminary work I discovered that, the largest mass change occurred from, the thirty percent sucrose solution. The least change occurred from the smallest concentration of sucrose solution, ten percent. This meant that I would use a range of sucrose solutions, either side of ten percent for my real experiment. Therefore for my real experiment I have decided, to use the following range of sucrose solutions: 4%, 8%, 10%, 12% and 14 % sucrose. Using this range will, give me an accurate result for the sucrose solution in the potato. Initially, for my range I had decided to use, three percentages of sucrose solution, on either side of the ten percent sucrose solution. However, there were not any other sucrose solutions available, so I had to do alter my range.
