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Investigation on Osmosis using a potato.

Extracts from this document...

Introduction

Investigation on Osmosis using a potato. Aim The aim of the experiment is to see osmosis in potato's by changing the variable which is going to be concentration, we are going to see at what concentrations the potato gains mass, and at which concentrations the potato loses mass, and at which individual concentration does the potato not gain or loss mass at all, this will be the equilibrium. Scientific Theory Osmosis is the movement of water molecules across a partially permeable membrane from its region of high water concentration to a region of low water concentration. In this test I have a range of choices in which I will have to choose from to prove a scientific fact. I have the options of testing with the potato to see how temperature will affect its rate of osmosis/plamolysis, and how the potato will be affected by osmosis when increasing/decreasing its surface area. But there is another choice and it is that I can change the concentration of solution which the potato is put into and this will very much affect the rate of osmosis/plasmolysis on the potato. I have decided to make the variable the difference in concentration because it will give a wider range of results helping me to analyse it better. Baring this in mind I also have to consider that these are my non variables: * Surface area * Solution volume * Duration of experiment * Temperature * Solution * Balances/Weighing scales * Conditions Theory 1. A partially permeable membrane is something with really small pores so very small particles can pass through like water molecules but bigger molecules like glucose molecules can not pass through. In this experiments case the partially permeable membrane is the potato and water will pass through this. Depending on the concentration of the solution the more or less the water shall pass through. 2. Water molecules can pass through the partially permeable membrane in both ways so this means the potato can lose or gain weight depending on the solution concentration. ...read more.

Middle

If the volume of one solution in a test tube is higher or lower than another, will affect the pattern of results later on. In this experiment to make it a fair test we will take down the mass of the potato on the allocated time then we will put them back in the solution and weigh them again in 2 hours to check if it has done all the osmosis it can do if it has done all of the osmosis it possibly can then it will have no change in mass. We will also make sure that the potato is fully covered by the 11 different kinds of solutions. This is because, is the potato is not covered up by the solutions, the effect of osmosis might not occur to the fullest. Small things such as a dirty test tube, and a slightly cracked measuring cylinder could still affect the results, and therefore we will take these into account as well. To avoid such things as these one should carefully check all equipment We will be using this range of solutions: Amount of 1 M sucrose (ml) Amount of water (ml) What molar sucrose solution this is. 0 30 0 Molars 3 27 0.1 Molars 6 24 0.2 Molars 9 21 0.3 Molars 12 18 0.4 Molars 15 15 0.5 Molars 18 12 0.6 Molars 21 9 0.7 Molars 24 6 0.8 Molars 27 3 0.9 Molars 30 0 1 Molar Method 1. We will get the following equipment: * Cutting tile - to cut the potato on * Knife - to cut the potato * 25 cm Measuring cylinder - to measure the solutions * Distilled water - part of the experiment * 1 molar sucrose solution - part of the experiment * Potatoes - part of the experiment * Tissue paper - to dry the potatoes after the osmosis takes place * Balance - to weigh the potatoes * Cork borer - to cut out potato cylinders * Get a ...read more.

Conclusion

If I were to repeat the experiment I would have possibly found a machine to cut the potato as it would ensure that all potatoes would be the same weight and dimensions. Even though I did measure the surface area it sill would not be fair because they still were not the same size. As well as the potato I could have found a more accurate way to measure out the solutions and to determine the molar concentrations. Perhaps I could have used a burette which would be a lot more accurate and leave less room for human mistakes. This would ensure that I have an accurate amount of fluid in each test tube. I could also weigh each potato cylinder on a more accurate scale, e.g. not to 0.00g but to 0.0000g. There were not any out of the ordinary results, but some were not as close to the line as others. This may have been caused by human error. When the potato chips were removed from the test tubes and dried I may well have dried some potatoes more thoroughly than others and so some would have more excess water, which would add to the mass. If the experiment was repeated I could 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 complete comparison of my results with my initial prediction. To extend the research and the amount of knowledge of this experiment I could use different potatoes like sweet potato because obviously they will have different concentration amounts inside. I could extend this even more because I could use different tissues instead of potatoes. This will make a lot of difference because it will extend my knowledge from osmosis in a potato into osmosis in an organism/ plant. By Abdelaziz Marzoug Osmosis Coursework 10 E By Abdelaziz Marzoug Osmosis Coursework 10 E ...read more.

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