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Osmosis Coursework

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Osmosis Coursework Osmosis is the movement of water particles through a partially permeable membrane, water molecules move by osmosis from where they are more water particles to where there are less water particles. This diagram above shows the amount of water particles in two different cells (A & B) and a partially permeable membrane, which means particles of a certain size can get through it. As you can see by looking at the diagram, side A has more water particles whereas side B has more solute particles. Together, both sides will even out the amount of water particles by osmosis. This will mean that water particles will pass through the partially permeable membrane from side A to side B. The blue arrows show this process. The direction of the blue arrows is where some of the water particles will move by osmosis to side B. Solute molecules cannot pass through the partially permeable membrane as the particles are too big so they stay on the same side and the water particles will travel by osmosis to whichever side needs more water. When the concentration of water is the same, there will be equal movement but in both directions. Preliminary Work For this experiment I cut 3 pieces of potato of which were all of similar size and mass, I then removed any excess moisture for the slices by using a paper towel. ...read more.


I think this because I think the potato has a similar concentration to the solution. For the 0.50M I predict that the potato will lose water and become flaccid because I think there will be less salt in the potato than the solution. This means that the water concentration of the potato is greater that the solution concentration of water. The mass decrease will be greater than the solution concentration of water. The mass decrease will be greater that the change in mass for the 0.25M solution. For the 0.75M I predict that results for this solution will be similar to those of the 0.50M, however the potato will have lost more water than the previous potato in the 0.50M solution. I also predict that this potato will become more flaccid than the potatoes in the last 3 solutions, furthermore I predict that this potato will have shrunk down I size compared to it's original length. For the 1.00M I predict that this potato will have shrunk the most in size, have the lowest mass and be the most flaccid compared to potatoes in the previous experiments. I also predict that the average concentration of salt in a potato is between 0M and 0.5M, as a potato has a weaker concentration to a 1.00M solution. ...read more.


* Ensured the potatoes where in the solutions for no longer that 30 minutes Conclusion After conducting my experiment I have decided that it was a good idea to repeat my experiment twice as my results are now more reliable. I have discovered about osmosis and it's effects on cells as my experiment proves, different strength solutions let in / let out water by osmosis. I have also found out that a potato contains a weak salt solution. I have found out that salt cannot be passed through a partially permeable membrane and that the water concentration could be moved around. My predictions were correct for the 0.25M the % change was negative so the concentration of salt solution in a potato must be around 0.1/ 0.2 M. My improvements were successful in making my experiment fairer and my preliminary work was a success. Evaluation The two sets of results where different and don't look similar on the graph, I must have gone wrong somewhere and this is why my results don't tally. I think that the mistake was on the second experiment as on the graph there are many results spread out all over the place, whereas on the 1st experiment graph we can see a nice curved line that indicates good results. ?? ?? ?? ?? Page 1 of 6 Thomas Grayson 11J ...read more.

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