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Osmosis Investigation.

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Introduction

Osmosis Investigation Skill area P: Planning Osmosis is the diffusion of water molecules from an area of high concentration to an area of low concentration through a partially permeable membrane. In this investigation I aim to find out how the amount of osmosis differs in potato chips in water and sucrose solutions of differing strength. Fair Test Variable Input Strength of solution Controlled Size of potato chip Temperature Quantity of solution Treatment of potato Outcome Change in length of strip The strength of the solution will affect how much osmosis occurs because with a weaker sucrose solution there will be a higher concentration of water. Therefore, by osmosis water molecules will pass through the minuscule holes in the membrane of the potato, which has a lower concentration of water, and cause it to gain weight and size. I will keep the other variables (listed below) constant so that it is a fair test and I am only changing the strength of the concentration. This way I will only be measuring how osmosis differs in solutions of varying sucrose concentrations. The size of potato chip is important because if one strip is longer than another the amount it has enlarged compared to the other will be inaccurate. ...read more.

Middle

End length (2dp) Percentage increase (1dp) Flexibility 1 2 Average 1 2 Average 0 24 6.00 6.00 6.00 6.20 6.30 6.25 4.2 Firm 0.2 24 6.00 6.00 6.00 5.80 5.90 5.85 -2.5 Quite firm 0.4 24 6.00 6.00 6.00 5.60 5.60 5.60 -6.7 Some rigidity 0.6 23.5 6.00 6.00 6.00 5.40 5.30 5.35 -10.8 Slightly flexible 0.8 23.5 6.00 6.00 6.00 5.20 5.30 5.25 -12.5 Flexible I used two potato strips for each concentration of sucrose and took an average of the start and length this way I could eliminate any results that were unreliable or inaccurate and have firmer evidence. I made one change to my plan and used only five different strengths of sucrose and left out the 1M variable. This way I saved time and still had a wide enough range of results to show me some clear conclusions. I could not control the temperature in this experiment and, therefore, it varied slightly throughout the investigation. I was unable to measure the temperature throughout the 24 hours of the experiment when the potato chips were left in the solutions. The temperature would not have differed much and would have stayed very close to the 24�C that the room temperature usually is in the specific room. ...read more.

Conclusion

I measured each strip by the length and width. I think I should have measured each strip by mass as well because two potato strips of the same dimensions could have different masses. I believe that the mass could affect the amount of osmosis more than length because a heavier chip would have a less water potential. I could also have used a wider range of sucrose concentrations with a smaller gap between them so I could see more intimately the relationship. Also this would make the results a lot more accurate. My investigation showed me that there is an obvious relationship between the concentration of sucrose and the amount of osmosis in a potato chip. To extend my investigation I could look to see if the amount of osmosis follows a similar pattern if a different solution was used instead of sucrose. It may also be interesting to investigate if the belief that keeping potatoes submerged in water is the most effective way to keep potatoes fresh and prevent them from going off. Also I could compare the rate of osmosis in a potato chip to the amount of osmosis in another object which has a partially permeable membrane. ...read more.

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