Osmosis Coursework How does the amount of sugar in a water solution affect the process of Osmosis in potatoes? Introduction In this experiment, I will be looking to investigate the effect of varying concentration of a sugar solution on the amount of osmotic activity between the solution and a potato chip of a given size. The potato chips were cut to size, then added to a water based sugar solution, where the variable was the amount of sugar added.
The potato chips were cut to size by a potato chip cutter, leaving them all roughly the same size, then further adaptations to the potatoes were made using a sharp knife in order to allow the potatoes to be re-sized to a more accurate size in comparison to the other potato chips. Strategy To create a fair test, certain aspects of the experiment will have to be kept the same whilst one key variable is changed.
I have chosen to vary the concentration of the sugar solution, which will give me a varied set of results from which I shall make a conclusion. These aspects of the test that I maintained and kept the same were; The amount of water that is used in which the sugar will be added to form the sugar solution as if the amount of water is changed, the general ratio of sugar to water (n+1 to 100ml of water) will be changed, giving different results to what it should be if the ratio was maintained on all experiments.
To make sure that the amount of water used was the same for all the experiments that were carried out, I filled up a tube that was capable of filling up to just over 100ml, with 100ml, as there was accurate measurements leading up the side of it, making it simple and easy to read. I then added this water to the test beaker, meaning that 100ml was in the beaker each time. The initial mass of the potato was kept as close to the identical mass as was possible with the resources given, as any major differences in the mass of the potato chips would not give reliable results.
I did this by first slicing the potato with a chip slicer, which left the chips the same thickness and diameter, but all of different lengths, so a sharper knife was used to slice the ends off at the same points, leaving all the chips the same length. After this, the chips were weighed to see if there was a major difference could be seen regarding the mass of the chip, and if a difference was seen, further modifications would be made to the chip.
The time that the chip was kept in the water based sugar solution as this would be needed to make comparisons with later experiments. This was done by placing all the potato chips in the sugar solution at the same time, then, when all added, a timer would be immediately started for all chips, and later stopped at 20 minutes and the potatoes would be taken out, slightly dried and weighed again to find the new mass which would later be needed to find the change in the mass of the potato chips.
The amount of sugar used to create the sugar solution had to be kept the same as the strength of the sugar in the solution would affect the amount of water molecules that would be able to pass through the semi-permeable membrane that is the potato chip’s cell wall. This would affect the results that I would later collect and make the overall results unreliable as the overall mean and range would contain incorrect/irregular data, making it unreliable. The method of obtaining the results and carrying out the experiment were as follows; 1.
I took one average sized, checking that it was healthy and showed no signs of major damage. 2. Using a potato chip slicer, the potato was sliced into multiple pieces. 3. The potato chips that were made from the centre of the potato were chosen, and were all sliced at both ends to remove the skin and equal the sizes. 4. The potatoes were then weighed on a balance to identify their mass, so they can be recorded or modified again to become the same (or of a similar mass). 5. I then gathered six Pyrex beakers and filled each container with 250ml of distilled water then added the varying amounts of sugar to them. . I then used a timer to allow the chips to be submerged in the sugar solution, which created a fair test as Osmosis would occur in the same amount of time. 7. The chips were then dried slightly on paper towels to rid them of any excess water. 8. They were then weighed again on the same scales, which will give the correct results to the extent of that particular balances weighing system. 9. The test was then repeated a further two times in the same way as the first, in order to produce more overall reliable results. Collecting Data
There were certain factors of the test that might have affected the experiment, for example, the amount of water that was used for the sugar solution as if the amount of water is changed, the general ratio of sugar to water (n+1 to 100ml of water) would be changed also, giving us different results to the ones from the other experiments. To make sure that the amount of water used was the same for all the experiments that were carried out, I filled up a tube that was capable of filling up to just over 100ml, with 100ml, as there was accurate measurements leading up the side of it, making it simple and easy to read.
I then added this water to the test beaker, meaning that 100ml was in the beaker each time. Also, the potato gives a chance that the results will be altered as the mass of one potato cannot be identical to another using the equipment given. This was solved by first slicing the potato with a chip slicer, which left the chips the same thickness and diameter, but all of different lengths, so a sharper knife was used to slice the ends off at the same points, leaving all the chips the same length.
After this, the chips were weighed to see if there was a major difference could be seen regarding the mass of the chip, and if a difference was seen, further modifications would be made to the chip. Also, the mass of the potato is a dependent variable; this means that it will be measured throughout the experiment. I will measure the mass of the potato in grams and the potato chip will be measured before it is put in the solution, and after. This will allow us to see whether osmosis has taken place, and to what extent.
To ensure that the results produced were as reliable as possible, the experiment was repeated three times, all keeping the factors the same (amount of water/sugar etc. ) in order to allow each experiment to be as reliable as possible so comparisons between the experiments using the data will be accurate as the data used to compare will be reliable. As each potato chip was roughly the same size, I was able to compare the results and check for any outliers within the data, which would be easily spotted as the results should have been (and were) within the same range.
Interpreting Data Evaluation The experiment was very successful in my opinion. I obtained a large quantity of very accurate results from which I was able to create an informative graph. I think I took enough results for the amount of concentrations that I was using, and the time that I used for the experiment to last was enough to allow sufficient osmosis to occur. However if I was to repeat the experiment I might increase the time of the result to allow more osmosis to happen and possibly find out the saturation point of the chips.
The range of concentrations was adequate but I would possibly create more concentrations if I repeated the experiment so that I would have more varied results. This way would have allowed me to also find out the isotonic point far more accurately as the one that I estimated is very approximate. The cutting of the potatoes was the most difficult part of the experiment as although I was recording my results by mass, it could well have affected the surface area and so the overall rate of osmosis.
If I were to repeat the experiment I would have possibly spent more time cutting the potatoes to more of an identical size as it would ensure that all potatoes would be the same weight and dimensions. As well as the potato I could have found a more accurate way to measure out the solutions and to determine the concentrations, I could have done this by using a burette, which would ensure that I have an accurate amount of fluid in each test tube. I could also weigh each chip on a more accurate scale, e. g. not to 0. 00g but to 0. 0000g.
There were not any outliers located in the results of the test, but some were not as close to the line as others. This may have been caused by human error or doings. When the potato chips were removed from the test tubes and dried, I may have dried some potatoes more thoroughly than others and so some would have more excess water would add to the mass. If the experiment was repeated, I would find another way to dry the potatoes that would ensure that all were dried in the same way for the same time. However with all this said I think that the experiment was truly successful and I was very pleased with the completed results.