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# biology coursework - osmosis in potatos

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Introduction

Osmosis in Potatoes Aim: To measure the difference in mass of potato chips in a variety of sucrose concentrations. Variables: The variables that I can change in my experiment are: the length and width of the chip, type of solution, the time the chip is left in the solution, the temperature of the sucrose solution, stirring or not stirring the solution or whether the potato chips are skinned or not. Preliminary Test: I did a preliminary test to find out a little about osmosis and the possible problems that I may face while doing the actual experiment. I got a potato and cut 3 chips of it which were all the same length and width. Then we got 3 test tubes with the same amount of water in them but with three different concentrations: pure water, weak sugar solution (2 spatulas of sugar) and a strong sugar solution (8 spatulas of sugar). I then added the chips and left it for 15 minutes. I then took them out and measured them, the chip in the pure water got bigger by 0.1cm and it got harder and stiffer, the chip in weak sugar solution stayed the same and the chip in strong sugar solution got smaller 0.2cm and it got floppy and softer. To improve it for the main experiment I will have to cut the chips more accurately, weigh the chips before and after putting them into the sucrose solution. ...read more.

Middle

to a low concentration (the chip), causing the chip to swell up. Results: Conc. (M) Mass At (g) Start Mass At (g) End Diff In Mass Average (g) 1 2 3 1 2 3 1 2 3 0.0 3.50 2.81 3.20 3.55 3.16 3.26 +0.50 +0.35 +0.60 0.48 0.2 3.03 2.98 3.04 3.08 3.06 3.08 +0.50 +0.08 +0.40 0.33 0.4 2.11 3.19 3.11 2.12 3.19 3.14 +0.10 +0.08 +0.30 0.16 0.6 2.70 3.35 3.32 2.89 3.55 3.53 +0.19 +0.20 +0.21 0.20 0.8 3.03 3.06 3.15 2.67 2.75 2.72 -0.31 -0.31 -0.43 -0.35 1.0 3.50 2.43 3.05 2.73 2.40 2.69 -0.78 -0.30 -0.36 -0.48 Analysis: From my graph I can see that as the concentration increases the weight of the chip stars to decrease. The chips in water grow by an average of 0.48g.As the concentration starts to increase the weight of the chip starts to decrease, because the water particles in the chip were it is high concentration will diffuse into the solution were it is a lower concentration. As the sucrose increases the chip still grows but not as much. As the concentration increases the chip stays the same at a certain point this is because the concentration and water inside and outside the chip are the same, this is known as equilibrium and this happens at approximately 0.5M. ...read more.

Conclusion

For this problem it could have been solved if each group had their own pair of scales. The chips were not the same weight to start of with so the change in weight was not the best way of looking at the results, its not a very fair test Another problem I came across was that we had to wait for the scales a long time and this made the chips dry out as we were waiting. For this problem it could have been solved if each group had their own pair of scales. The chips were not the same weight to start of with so the change in weight was not the best way of looking at the results; it's not a very fair test. A better way is too look at percentage change in weight. If I was to do the experiment again I would change the temperature of the water and this is another variable. I would have to change the temperature of the sucrose solution from low temperature and gradually get to a higher temperature then add the potato chips to each concentration. I could use a kettle to boil the water to the different temperatures. After adding the chips to the boiling tubes and leaving them in the solution for the same amount of time e.g. 15minutes, you can take the chips out of the boiling tubes and see which chips have increased, decreased or stayed the same. ...read more.

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1. ## Osmosis Coursework

I recorded the results in line graphs. On the Y axis the mass/length is plotted in g/cm. On the X axis the beakers containing solutions of varying concentrations are plotted. The straight lines plotted on 2 and 5 on the Y axis shows the masses and lengths of the potato chips before osmosis.

2. ## Osmosis in Potato's

Figure 1: Shows us how osmosis takes place within a liquid. There are many factors that can affect it such as the concentration of the solutions can have a big difference in the rate of osmosis, the room temperature, and the area or volume over which the osmosis is to take place.

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