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In this investigation, I plan to see which factors would affect the rate of osmosis in potato cells

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Introduction

Osmosis Introduction: In this investigation, I plan to see which factors would affect the rate of osmosis in potato cells. Osmosis is the concentration gradient moving from a high concentration to a low concentration through a partially permeable membrane. I will weigh the potato chips before and after, if the weight increases, it shows that the potato chip has a lower concentration than the liquid it is in. Therefore, osmosis has taken place. Vocabulary (Taken From the Internet- Check Bibliography) Osmosis- the diffusion of fluids through a semi-permeable membrane or porous partition. Concentration Gradient- The change in solute concentration per unit distance in solute. Concentration gradients cause Fickian diffusion (spreading) of solutes from regions of highest to regions of lowest concentrations. In slow-moving groundwater, this is the dominant mixing process. Partially Permeable Membrane- A semi permeable membrane (or more accurately a selectively permeable membrane) is a membrane which will allow certain molecules or ions to pass through it by diffusion (sometimes "facilitated diffusion"). The rate of passage depends on the pressure, concentration and temperature of the molecules (or "solutes") on either side, as well as the permeability of the membrane to each solute. Factors that affect osmosis: Temperature- if the temperature is high, the particles will gain kinetic energy. This would increase the rate of osmosis. Because the particles have kinetic energy, they move around. This could result in them bumping into the membrane. If this does happen, the chance of molecules getting through the membrane increases, therefore; the rate of osmosis does too. ...read more.

Middle

Each solution was 10mm� to make it fair. The different solutions were chosen to see if the concentration of sugar affected the experiment in any way. The test tubes were left for three days then weighed again. The method was repeated thrice for each different solution the potato chip was put into. This is so that an average could be obtained to make sure my results were as accurate as possible. A simple guideline to follow: 1) Cut the potato up into chips of the same size 2) Weigh them, make sure they all weigh the same 3) Measure out 10mm� of every solution used 4) Put the solutions into a test tube each, then put the test tubes into a test tube rack 5) Leave the test tubes for three days 6) Dry the potatoes with tissue so no water is left on them 7) Weigh them again to see the difference Potato chip in test tube. Safety Although the experiment seems extremely safe, all things must be considered. Knife- the knife may be unsafe if not used properly whilst chopping the potato. It could cut you or someone around you. If this does happen, apply pressure to the cut for ten minutes and elevate the part of body which has been cut. The Solutions- although the solutions are not extremely dangerous, we do not know the affect of the solutions if they somehow entered our body. If this did happen, and irritation began, you would have to notify your doctor. ...read more.

Conclusion

Also, if we had used more types of sugar solutions and possibly other types of solutions, it would have given me more results and maybe even more accurate results. Another way we could have improved the experiment is by doing all of the different solutions one after the other. This would mean three days of a water solution, three days of a 0.2m solution, and a further three days each for a 0.5m and 0.7m solution. This would make it easier and would mean that it is not as confusing to see which solution is which if some people did not label theirs. However, if we did change the measuring method, how we dried the potato and how many solutions we used; it would prolong the experiment and make it more complicated than it actually has to be. It would also mean the time scale would be longer as the experiment would take much longer to do. If the molarity levels were more precise, this would mean even more accurate results. I used 0.2m, 0.5m and 0.7m solutions but more could have been used. This too, would have made the experiment a lot more complicated. Also, the things I kept consistent such as the temperature would have affected the rate of osmosis. It would be good if I could have changed these to see what would have happened. Considering the method and equipment used, I believe this to have been a very successful experiment and my results to be helpful and accurate. I am satisfied with how I did the practical and the results obtained. ...read more.

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