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The effect of concentration on potato discs

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Introduction

John Saunders - 10R 23/9/01 What is the effect of concentration on the size of potato discs? Research The main process that will take place in this experiment is osmosis. To explain osmosis more, I've conducted some research to help me decide what will happen in the experiment, and create a prediction, and also perhaps help me set up a good method to get the best results from my experiment. What osmosis is: Osmosis is the movement of water from an area of high concentration to an area of low concentration through a semi-permeable membrane. The process of osmosis: Salt Water High concentration of salt Semi-permeable High concentration of water Low concentration of water membrane Low concentration of salt This generally shows the osmosis process. The semi-permeable membrane isn't a solid wall, so molecules can get through it, but only small molecules are deceptive enough to do it. In this case, only the water can get through it, and the salt solution can't. Osmosis is basically where the cell tries to form an equilibrium between itself and the solvent or solute around it. In the case of this diagram above, the side with the lower concentration of salt solution (higher concentration with water), passes on water to the side with the higher salt solution (lower concentration with water), to dilute it. This is to try and form an equilibrium between the two sides of the membrane. ...read more.

Middle

I will do this by using exactly the same weight of potato discs, and using exactly the same amount of concentrated solutions. In this case, I'm using 7 pieces of potato, each weighing 0.6g, and 7 x 30ml of concentrated solution. If I test fairly, this should mean that I wouldn't need to check on the statistics I found on the discs as closely. I will use 7 different concentrations, ranging from 0.05, up to 0.25, so I have a good range of statistics I can look at. From this, I may be able to see if I can find a set pattern between the relationship of concentration and the size of the discs. Depending on the time we have for the experiment, I will probably spend longer setting the experiment up, as this experiment needs time to develop. This would mean that I wouldn't need to wait another 3 or 4 days finding results if I repeat the experiment, for if I did something wrong the first time in setting the experiment up. I will record the results in a table, so that they are easier to compare and contrast, and so that I can comment on my findings a lot easier. Because there are seven different results to compare, I don't want to waste valuable time looking through paragraphs for data, which could be so easily found in a table. ...read more.

Conclusion

This could have affected how much it took or gave within the salt solution concentration, so we shouldn't have left some skin on one or two of them if there was any on. I did measure all the measurements exactly, so the only other factors I can think of are how much fluid was on the discs when we took them out of the concentrations, or, how much fluid was on the weighing scales if any excess water from earlier weight measurements was on them. This is especially true because were talking about tenths of a gram with this experiment. One particular result that I thought that went wrong was the 0.15 and the 0.175 results. This is because the trend is that the weights gradually decrease as the concentrations get higher. These trends break the sequence, as they gain weight dramatically from the 0.125 weight, which in comparison, weighed just over half of the 0.175 weight, even though it is a higher concentration. I personally don't think the conclusion earlier on in the analysis of the experiment is enough to support or undermine my experiment, for the simple reason that the experiment has so many flaws as far as the wild results are concerned. Although there do seem to be some trends within the weights, these still don't follow any exact trends, and we can't say they would follow any strict pattern if range of the concentrations was greater. 7 1 ...read more.

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