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# I am going to investigate whether altering the solute concentrate of a potato cell changes osmosis

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Introduction

Plan I am going to investigate whether altering the solute concentrate of a potato cell changes osmosis. My input variable will be the concentration of sodium chloride solution (NaCl). The different concentrations that I will be using are: * 20%- 12ml NaCl + 48ml Water * 40%- 24ml NaCl + 36ml Water * 60%- 36ml NaCl + 24ml Water * 80%- 48ml NaCl + 12ml Water * 100%- 60ml NaCl + 0ml Water My constants will be: * Length of potato- 30mm * Time in solution * Volume of sodium chloride solution- 60ml� * Temperature of room- �21�C I predict that the potato left in the more concentrated solution will lose more mass and get smaller than the potato left in the weaker solution, which will lose less mass and size in comparison. This is because the water from the potato will transfer from an area of higher concentration to an area of lower concentration, in relative terms this means that as the potato contains a higher concentration of water than the NaCl solution, therefore the water from the potato will be displaced into the surroundings, consequently losing size and mass. This theoretically proves my prediction correct, but I will carry out an investigation to prove that my prediction is precise. Method I am now going to explain the method that I will use in creating a safely executed investigation. * Firstly I will cut the slices of potato that I need, to the correct length of 30mm.; * I will then record the weight of ...read more.

Middle

29mm 3.66g 2.96g 60% 3 30mm 28mm 3.68g 3.00g 60% Average 30mm 28mm 3.72g 3.05g 80% 1 30mm 28mm 3.90g 2.93g 80% 2 30mm 27mm 3.82g 3.06g 80% 3 30mm 27mm 3.51g 2.88g 80% Average 30mm 27mm 3.74g 2.96g 100% 1 30mm 27mm 3.61g 2.66g 100% 2 30mm 26mm 3.76g 2.82g 100% 3 30mm 28mm 3.69g 2.53g 100% Average 30mm 27mm 3.69g 2.67g These results showed me that my method is correct, and if I carry it out properly I can obtain valid results. Results Salt Solution Test Length Before Length After Mass Before Mass After 20% 1 30mm 29mm 3.75g 3.10g 20% 2 30mm 30mm 3.80g 3.34g 20% 3 30mm 28mm 3.63g 3.02g 20% Average 30mm 29mm 3.72g 3.15g 40% 1 30mm 27mm 3.79g 2.60g 40% 2 30mm 29mm 3.85g 3.11g 40% 3 30mm 29mm 3.50g 3.14g 40% Average 30mm 28mm 3.71g 2.95g 60% 1 30mm 29mm 3.84g 2.85g 60% 2 30mm 29mm 3.67g 2.92g 60% 3 30mm 27mm 3.60g 2.47g 60% Average 30mm 28mm 3.70g 2.75g 80% 1 30mm 28mm 3.54g 2.89g 80% 2 30mm 27mm 3.88g 2.64g 80% 3 30mm 27mm 3.89g 2.63g 80% Average 30mm 27mm 3.77g 2.72g 100% 1 30mm 26mm 3.54g 2.42g 100% 2 30mm 28mm 3.56g 2.93g 100% 3 30mm 27mm 3.86g 2.62g 100% Average 30mm 27mm 3.65g 2.66g I do not need to repeat any of my tests as my results are clear an accurate. Conclusion My results tell me that my prediction is accurate. ...read more.

Conclusion

This would allow me to easily spot any anomalies and I could also plot all the points on a graph to get a more accurate line of best fit. Also, if I did the experiment again I would use 0% concentrate, distilled water. Another way to make my results more accurate in terms of finding the isotonic solution would be to do the experiment again but concentrate the investigation on a smaller area. This would give me more detailed results, so I could estimate the concentration of the isotonic solution. I could also investigate osmosis further by looking at how the volume of the potato changes in different concentrations of solution. This would look at the idea that cells should go turgid in pure water as they gain water, and flaccid in strong salt solution as they lose water. I would conduct this experiment in the same way except I would record the volume of the potato cylinders instead of the mass. I'd do this by filling a container with water and then putting the potato in. I'd collect the water that is displaced and the volume of this water would be the same as the volume of the potato. I'd take these measurements before and after osmosis and use the results in exactly the same way as I have when investigating mass. If I could change one thing about my experiment is the timing. My specified time was one hour, but due to circumstances the samples were actually left for twenty-four hours. This probably affected my results to some degree, but the end result is still as I expected. ?? ?? ?? ?? Osmosis Coursework ...read more.

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