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Osmosis. I am going to do this experiment by placing potato chips into different concentrations of salt solution and measuring their change in mass.

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Introduction

Osmosis Coursework Investigation: To find out the concentration of solutes in the cytoplasm of plant cells Aim: To find out how much salt there is in a piece of potato I am going to do this experiment by placing potato chips into different concentrations of salt solution and measuring their change in mass. This will show me how much osmosis is taking place in the different concentrations of salt solutions. Chemicals and apparatus: 12 potato chips of equal dimensions Salt solution Distilled water 4 beakers Measuring cylinders (50cl) Electronic scales Knife Paper towels Variables: Independent -The independent variable in this experiment is the concentration f the salt solution because this will effect how the mass of the potato chips changes. I will be using 4 different concentrations of salt solution. Dependent -The independent variable in this experiment is the change in mass of the potato chips because this will be affected by the concentration of the salt solution. Controlled -The amount of time that the potato chips are left in the salt solution for, because if some of the chips are left in the salt solution for longer than others then they will have more time for osmosis to take place and it would therefore be an unfair test. I am going to leave my chips in the salt solution for 52 hours. -The volume of salt solution used because this may effect how the mass of the potato chips changes. ...read more.

Middle

Whereas is the high concentration salt solution the osmosis is going from inside of the potato to outside. When the osmosis goes from outside the potato to inside it the potato cells fill with water and become turgid. When the water goes from inside of the potato to outside the potato cells loose the water inside them and become flaccid. Prediction: I predict that the chips in the 0.1M salt solution will gain the most mass because when I did my preliminary experiment using salt solutions of 0.0M and 0.5M I found that the average percentage mass change in the 0.0M solution was 22.46%, but in the 0.5M solution it was -29.64%, this shows that the chips in the 0.5M solution actually lost mass; this was because there was a higher concentration of water inside the potato chips than in a 0.5M salt solution and therefore the net movement of water was from inside the potato to outside. The reason I am using the 4 concentrations of salt solution that I am is because they are all between 0.0M and 0.5M, and in my preliminary work I found that 0.0M was too low a concentration because the chips gained mass, and 0.5M was too high a concentration because the chips gained mass. Results: These are the results that I got from my experiment: Salt Solution concentration Chip No. ...read more.

Conclusion

I think that the Percentage Mass Change graph is slightly more reliable than the Average Percentage Mass Change graph because the Average Percentage Mass Change graph uses a line of best fit, which is not as reliable as the curved line which I used on the Percentage Mass Change graph. Conclusion: Overall I think that this experiment worked well. However I think that I could improve it next time by * Running each of the concentrations of salt solution 5 times instead of 3 so that I would get a more reliable average result from each of the concentrations of salt solution. * Using another 4 concentrations of salt solution- 0.15M 0.25M 0.35M 0.45M I would do this because it would mean that I would get a more accurate final result from the experiment. * I would create a graph showing the Mass Change as well as the two graphs that I made during this experiment showing the Percentage Mass change and the Average Percentage Mass change. I would do this because it would show me the actual Mass' that the potato chips gained and lost during the experiment as well having the other graphs showing me the percentage mass changes. I found that the concentration of solutes in the cytoplasm of plant cells, or in other words the amount of salt there is in a piece of potato was approximately between 0.125M and 0.15M. I found this out because between these two concentrations of salt solution the potato chips neither gained nor lost a measurable amount of mass. ...read more.

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