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Experiment to investigate the Process and effect of concentration of Osmosis

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"Experiment to investigate the Process and effect of concentration of Osmosis" Background knowledge Through previous experiments, and notes we've learnt that Osmosis is a process, which uses the method of diffusion to transfer water molecules from a low to high concentration. An example of this is in the "Experiment to investigate Osmosis". When we placed a sucrose solution into a beaker of water. The sucrose was held in visking tubing that acted as a partially permeable membrane. As we predicted, it allowed water molecules in, and so became turgid and heavier than before the experiment, but the sucrose molecules, were too large to pass the membrane, so the water remained the same. Prediction By using my background information, (which is solely based on previous class notes), I think that when the potato strip is placed in the sugar solution then it will be lighter when taken out after approximately 30 minutes, because no sugar particles will be able to pass into the potato cells, where as water molecules in the potato will be able to escape from the cells into the solution. However I think that the more that the solution is diluted with water, then the heavier the strip of potato will be. ...read more.


7. Take chips out after 30 minutes. Soak up excess water with tissue. 8. Weigh chip - record results. Fair Test To make the whole experiment a fair test, we have to make sure that that each of the six chips are all roughly the same size and weight, and that they are left in the water for the same amount of time. If we don't do this then the weight before and after will be completely different and the results will become unreliable. We also have to make sure that in the repeat the volume of sugar solution and water, that we selected to represent 100% is the same in every case. Otherwise different amounts of water and sugar solution may pass through the partially permeable membrane. Reliability The way that we have set up the experiment should leave us with fairly reliable results. The only possible ways that we could make the experiment unreliable is by using different sized chips and different molars of solution, and by leaving the chips in for different amounts of time. We also had to use the same potato. Making sure that all the equipment is clean is vital; because if a chemical is in the petri dish or in the measuring cylinder, it could affect the water. ...read more.


We were a little inaccurate, because we probably wiped some more than others, which could have led to some anomalous results. To make sure the potato strips were roughly the same length and width, this could be important in case the thickness of the potato affects the osmosis. Also we had to try and make sure all the potatoes spent exactly the same time in the solution, each of the six strips probably spent with a minute of each other. This was vital that they went in for the same amount of time, as they strips could change weight in seconds because of the random motion of the molecules. I think that the investigation was a very good way of investigating Osmosis; other methods that could have been used could be using rhubarb instead of the potato strips, or we could have done the visking tubing experiment. Where we have sucrose in the visking tubing, which we place in a beaker of water. The visking tubing then acts as the selectively permeable membrane. We could improve the experiment by making it more accurate, and making sure we act upon the variables I have made. If we had more time, we could see how the time effects the concentration of osmosis. We could also leave the strips in for a longer or shorter period, to see whether the strips are heavier or lighter. ...read more.

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