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  • Level: GCSE
  • Subject: Science
  • Document length: 3237 words

An experiment to show osmosis in potato chips in different concentrations of sucrose solution - also investigating how potato chips change in volume and weight when placed in different concentrations of sucrose solution

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Extracts from this essay...

Introduction

Factors affecting osmosis in potato tissue Introduction: I am going to design and modify an experiment used to show osmosis in potato chips in different concentrations of sucrose solution. I am also going to investigate on how potato chips change in volume and weight when placed in different concentrations of sucrose solution. I will also conduct a preliminary experiment before my final experiment. Aim: To investigate the effect of different concentration of sucrose solution on potato chips. Hypothesis: I would expect the potato chips to turn flaccid when they are placed in a strong sucrose solution because the water from within the cells will diffuse out leaving the potato flaccid. The potato chips left in the weak sucrose solutions should turn turgid in a weak sucrose solution, due to the water being absorbed by osmosis into the cells of the potatoes, this will make the potato chip larger in size. I should also be able to find some potato chips, which have neither increased nor decreased in size because the concentration in the potato is the same as the sucrose solution, so no mass or length would be gained or lost. Scientific knowledge: Osmosis is a type of diffusion, where the molecules move from an area of high concentration to an area of low concentration passing through a partially permeable membrane. When distilled water or a weak sucrose solution or a diluted sucrose solution is used, the water molecules will pass through the semi-permeable membrane into the potato. This is due to the fact that the water is more concentrated outside, so the molecules in the water will move through the permeable membrane, and in this experiment it will pass through into the potato. The potato chip will increase in length, and weight due to osmosis. When a strong sucrose solution or a concentrated sucrose solution is used, the water within the potato will move out of the potato through the semi-permeable membrane, and into the strong sugar solution, of which the potato is soaked in.

Middle

Graphs: See graph paper. Evaluation: Studying the results I obtained I realized that having three different concentrations were not enough, and I could increase the amount to six different concentrations. I only placed two potato chips into each solution, there weren't enough results and so to increase the reliability I will also increase the amount to three potato chips to each beaker. The length was hard to measure accurately, and so if I were a millimetre out it would have made a large percentage difference. I also realized that that length was very hard to measure and was difficult to measure the length precisely and weight the mass of the chips in two minutes. I have decided to measure the volume of solution instead of the length for my actual experiment, because the volume of solution is a lot easier and quicker to measure and is also more accurate. I will also be changing the volume of solution to 100cm3 of water, because 120ml was hard to calculate the percentage and so using 100ml3 would be easier to work out the percentage. The results collected are rather poor. There aren't enough concentrations for me to plot a good graph. It is also very hard to plot the graph when one of the results is an anomaly, and because there are only three concentrations it is very hard to defy which one is the anomaly, and even whether there are any anomalous results plotted. Conclusion: I have made some changes to my method and will be using the new method for my actual experiment. Final Experiment Introduction: I have done my preliminary experiment and with the experience gained from the experiment I have re-written the method and apparatus list to fit my new method. My experiment should work better this time due to the numerous changes and improvements made. Aim: To investigate the effect of different concentration of sucrose solution on potato chips.

Conclusion

I have realized that the volume of solution also increases as the concentration increases, and so when there is a low concentration the volume also decreases. Graphs: See graph papers Scientific explanation: The volume of water increase as the concentration becomes stronger, this is because the water in the potato chips' cells are in the area of high concentration and so the water moves out of the cells and into the solution. So when a weak solution is used the sucrose solution is more concentrated than the water within the potato cells, therefore the solution moves into the cells and so the volume of solution will decrease and the size of the potato chip increase. Evaluation: My results were better this time, but I still remain unsatisfied with the amount of results gathered. I think the experiment would of worked better if I could use more potato chips. Instead of only using three potato chips to a concentration I think I could of used five potato chips instead. When I did this experiment I was limited to half an hour to set up everything and so it was very rushed and I didn't have enough time to make my measurements accurate. Cutting the potato chips to all the same dimensions was very difficult because the dimensions are very small. The apparatus used was also very inaccurate, for instance instead of using a measuring cylinder I could have used a burette to make the reading more accurate. I increased the amount of concentrations from three to six but I still think six solutions are still very unreliable and that it should be ten or twenty different concentrations. When the experiment was conducted the temperature was not kept the same and this could increased or decreased the rate of which osmosis took place. Conclusion: Overall I think my experiment was relatively good, and if more modifications were made the experiment could have been better. My results were fair and I am pleased with the results.

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Here's what a teacher thought of this essay

3 star(s)

*** Overall a well planned and carried out experiment which needed more thought put into the discussion of results and the evaluation of the method.
Planning was well carried out with a trial experiment. The prediction could be made clearer. If the prediction could be made quantitative ( perhaps by doing some background research) this would be helpful
Obtaining results The student carried out and trial experiments and a good range of the independent variable with a fair number of repeats. The student should try to ensure all units and concentrations are clearly recorded. It would have been better to only use one method of recording the dependent variable. This would have allowed more time for repeating anomalous results.
Analysing Evidence and Evaluation The graph was not available to view. The student needed to explain the extent to which the conclusion supported the prediction and look at ways of improving the reliability of the evidence. The student should try to account for the anomalies mentioned.

Marked by teacher Stevie Fleming 01/01/1970

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