Risk Assesment:
There isn’t much risk involved, as it doesn’t have the need for any heat etc. However it is advisable that you’re careful with your equipment as if a petry dish splits or something to this affect then your results might be changed.
Background Information:
I have done a preliminary experiment, by investigating the change but using one sample of potato chip in each molarity, so I have been able to base my prediction on this as well as information from books and the Internet along with my own knowledge about the osmosis in plant and human cells. My results from my preliminary experiment are said in the prediction.
Prediction: I predict on the basis of my previous investigation and my own knowledge that Molarity 0 of sucrose solution (distilled water) will be the highest + percentage for example 0 might give +15% whereas 0.1 would give +12% my results will go on down and cross 0% increase/decrease, between molarities 0.4 and 0.6. Then the lowest result will be full molarity of sucrose solution (1), which will show around -15% decrease. The other results will differ between + and – 15% in roughly equal gaps each time. Explanation for these results; Osmosis is the passage of water through a semi-permeable membrane from a less concentrated solution (more water molecules) to a more concentrated solution (less water molecules) until there are equal concentrations of water on both sides of the membrane. The potato which is in full molarity will attempt to make equal concentrations of water on each side by passing water out of its cells into the full molarity solution and so there for it will decrease in size because it is passing water through its semi permeable membranes. It will increase in size the most in the distilled water because the chip is going to take on more water in attempt to balance the concentration of sucrose inside its cells with the distilled water on the outside. It will there for become bigger because it is taking on more water and its cells are expanding. It will neither decrease nor increase when the molarity of sucrose solution is the same inside the cells as out. Assuming the potato cells have equal amounts of sucrose solution as they do water, there will be no % change at around 0.5 molar, (half water, and half sucrose solution.) This is why there will be a change from + to – percent at 0.4 and 0.6 however it does depend on the molarity inside the cell. My results of percentages and molarities are taken from my background knowledge, in the previous experiments I have conducted.
Observation
My Results
Average Class Results (11 people)
Analysis
My Evidence shows that at lower molarities the potato chip increases in size, it crosses the x-axis on the graph (using the curve of best fit) at 0.36 molars. Then it begins to decrease in size from there when the molars are higher. On the class average percentage change graph of results, it does the same thing increasing at lower molarities, crossing the xaxis at 0.4 molars, and decreasing in size for molarities higher than that. There is a smooth curve of best fit on both graphs which is what you should expect and this backed up by the class average graph. Thus proving my prediction was correct.
I conclude that the reason for this result is, Osmosis is the passage of water through a semi-permeable membrane from a less concentrated solution (more water molecules) to a more concentrated solution (less water molecules) until there are equal concentrations of water on both sides of the membrane. The potato which is in full molarity will attempt to make equal concentrations of water on each side by passing water out of its cells into the full molarity solution and so there for it will decrease in size because it is passing water through its semi permeable membranes. It will increase in size the most in the distilled water because the chip is going to take on more water in attempt to balance the concentration of sucrose inside its cells with the distilled water on the outside. It will there for become bigger because it is taking on more water and its cells are expanding. It will neither decrease nor increase when the molarity of sucrose solution is the same inside the cells as out. This is shown in my results graph and table and backed up by the other graph and table because the average class results are close to mine and an average of 11peoples results is more reliable.
I feel my prediction backs up what my evidence shows to a good degree, there are no obvious anomalies and therefore the experiment was conducted as good as possible given the circumstances, I could have improved it with more knowledge and with better equipment etc.
Evaluation
My method for this project to get the evidence I feel was sufficient enough for the nature of the work that is to get a rough idea of how the osmosis works and to get good enough graphs to make a good conclusion. I feel my experiment went well as there were no major anomalies a few went away from the line but this is to be expected for an experiment of this type. The reliability of my results are backed up by the class results as the average results of 11people are more reliable than the results of one person, and my results fit much the same line and pattern. The quality of evidence is definitely good enough to support the conclusion. The method went smoothly and there were no mistakes in the results so this proves that the procedure was good enough to obtain my results. My results I think show a good understanding of osmosis and knowledge, backed up class results. The reliability is shown in the graphs and they show the correct patterns with curves on the graphs and a show of good reliable results.
I could have improved the experiment to get better results; by making more samples, using more molarities (0, 0.1, 0.2, 0.3, 0.4 etc…..). I could have investigated many more aspects like what happens when you use the same molarities but leave them in different temperatures or just investigate one molarity but change the temperature. I could investigate the time in which it takes for it to become turgid in distilled water; I could investigate the way the potatoes react with elements to gain more understanding of its properties. There are a lot of ways to improve my understanding of the initial experiment but to improve the results I’ve obtained I could as I have said investigate with more molarities but I could improve the initial method by using more accurate equipment, by using more accurate measuring methods, I could make sure the potato slices all have the same molarity inside them etc. I could also find a set of results which is perfect, the theoretical results. The evidence I gain from all of the extra small experiments and the small experiments to improve my current method would add to the quality of the evidence and back up my results further.
