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Osmosis investigation

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Introduction

Osmosis investigation Aim In my investigation, I aim to see how the water potential of a solution affects the mass of potato placed in it after twenty four hours. Prediction I predict that as the concentration of the sugar solution increases the mass of the potato will decrease. Science I predicted this because as the sugar solution becomes more concentrated then the water potential decreases because there are more sugar molecules. Therefore the water potential is higher in the potato so in theory, relating to the rule of osmosis which states that 'Molecules is a place of high water concentration should move to a place of lower water potential through a semi-permeable membrane' (Where the membrane is the cell membrane of the potato). Thus the water in the potato should move to the lower water potential in the sugar solution resulting in the potato decreasing in mass. Below is a diagram of the states of osmosis. My prediction relates to the diagram with low water potential. Pilot Study I am going to carry out a pilot study to find suitable ranges for my forthcoming investigation. ...read more.

Middle

following things: 1)Be careful with the scalpel 2)Clear up spillages and breakages 3)Never leave my experiment unattended Fair Test To make my experiment a fair test I will make sure I carry out the following: 1)Cut the potato to the same size every time this will reduce possibility of anomalous results. 2)Keep the experiment in a dry place away from sunlight to stop the climate affecting the results List of Apparatus 1)Six test tubes 2)Test tube rack 3)Six pieces of the same potato 4)Scalpel 5)Paper towels 6)Electronic Balances 7)Labels 8)Writing equipment 9)Water 10)1M sugar solution Diagram of Apparatus Method 1)First set up apparatus as illustrated on the last page using six test tubes and a test tube rack. 2)Place labels on test tubes consisting of: - 0% - 100% in 20% intervals 3)Cut a potato in to 6 x 3cm slices using the scalpel 4)Place the appropriate amount of mixture in each test tube (see concentration table) 5)Weigh each slice of potato and record in a table 6)Place one piece in each test tube making sure they are completely immersed in the solution 7)Leave for twenty-four hours 8)Store in a ...read more.

Conclusion

I can also conclude from my graph, that the concentration is indirectly proportional to the change in mass. This means that if we double the concentration then the change is mass will be halved. I can prove this by taking results from my graph. 20% = 0.4g 40% = 0.2g I can calculate the cell sap concentration by finding the equilibrium of the x axis and the line of best fit. This is the point where there is no change in mass and therefore has even water potential as the solution. This value is 50 % Evaluation My experiment proved to be useful because my prediction was proven and my theory was accurate. I don't believe that I had any anomalous results because the analysis was accurate. I would change the following things if I were to do the experiment again: I would take more results to increase the range of results and therefore the accuracy of the experiment. I would also experiment with different temperatures to prove the theory to work in extreme conditions. I would also make sure the potatoes were correctly dried and weighed to improve results. Peter Page Page 1 5/1/2007 ...read more.

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