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# How Does a Change in the Concentration of the Surrounding Solution Affect Osmosis in Potato Cells?

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Introduction

How Does a Change in the Concentration of the Surrounding Solution Affect Osmosis in Potato Cells Plan Osmosis - osmosis is the net movement of water through a semi permeable membrane from an area of water where the water is purer to an area where the water is less pure (purer meaning that the water has less other molecules other than water in it) I have to think of an experiment to see how a change in the concentration of the surrounding solution affects osmosis in potato cells, I will do an experiment which measures the amount of water lost or gained before an osmotic balance is reached (when the water leaving the potato is equal to the water entering the potato because the concentration of water in the cells and outside the cells are the same) in different concentration solutions of sucrose (ordinary sugar as in granulated sugar). The experiment will be. Make solutions ranging from 0.1-9 molar of sucrose. Use a cork borer to cut similar pieces of potato. Weigh the potato so you can measure the change in weight. Put the samples in a boiling tube with a solution for an equal amount of time then weigh the pieces of potato and use the percentage. The problem with using weight is that the potatoes surface area mass of potato, not water and more factors also affect osmosis apart from just weight of the piece of potato and water is easily lost or gained before weighing while being held in the air. ...read more.

Middle

> Put the pieces of potato in the different molar solutions in boiling tubes (0.1 - 0.9 molar solutions of sucrose) in equal amounts (25 cm3. > Put three pieces in each strength molar solution so that you can compare the results later so that you are less likely to get anomalous results from your experiment. > Leave the pieces in the solutions for the same amount of time (until the next lesson was what I did). > Take the pieces of potato out of the solution and work out the change in the weight of the potato pieces using the electronic scales, then use the results to find out the change in the percentage of the weight in the potato cells which would show the rough amount of water absorbed. Results The results of the first test went missing so I do not have them to show Sucrose Solution Molarity Weight Before Weight After Change in Mass % Change Water (0.0) 0.90 1.91 1.01+ 112.22+ 0.1 0.90 1.85 0.95+ 105.56+ 0.4 0.90 1.44 0.54+ 60+ 0.8 0.90 1.36 0.46+ 51.11+ Analysis In the experiment osmosis took place, the fact that the weight of the potato changed (due to change in the amount of water in the piece of potato) proves this since there was nothing apart from water and a small amount of sucrose in the boiling tube. ...read more.

Conclusion

> Used the same potato so that the potato pieces will have the same properties as each other (same concentration of water in the cells). Points To Improve On > I included only 4 solutions in the experiment, this range is far too few because I have to use a curved line to fill in a predicted curve instead of actual results. > The tested solutions should have been from a more narrow range (narrowed by the tests) so that the guess work was not needed. > I had to put the results in order as the results or the pieces of potato seem to have got switched at least once at some point. > I only had one piece of potato per solution in the end so anomalies were more likely to occur. > Potato held in the hand or left in the air may have dried before they were weighed a bit, this would affect the results. Conclusion If I did the experiment again I would; use each of the solution concentrations to get an accurate graph and put three pieces per solution to avoid inaccuracies as badly. Two points that may have affected the results. > The pieces were starting to smell badly afterwards, bacterial activity could have affected the cell structure and so the rate of osmosis > The beginning weights could somehow be wrong, I don't know how this could have happened but it would explain why the line is mostly the right shape but isn't in the right place. > > > > ...read more.

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