# Osmosis in a Potato Experiment

To find out which concentration of solution will produce the smallest change in mass in a potato chip, due to osmosis. The factors I could investigate:
Size of potato
Thickness of potato
Temperature of solution
Sugar or salt solution
Amount of solution
Concentration of solutionThe factor that I have decided to investigate is: Concentration of solution I will be investigating the effect of glucose solutions on osmosis in potato pieces. I will observe how the mass of potato pieces change depending on the concentration of a glucose solution. I have decided to investigate the concentration of glucose solutions because I feel it will give me a more varied result and be easier to investigate as I have suitable equipment. Equipment: [image] Preliminary work ==== By using preliminary tests I was able to determine the measurement of solution I should use. When doing my preliminary test I used 20ml of solution. I decided to change it to 8ml of solution, as 20ml seemed too much considering the small size of the potato and the test tube. In my preliminary test I also noticed that the potato pieces needed to be left in the solution for longer then 30 minutes at least, otherwise change in mass isn?t very noticeable and made it hard to compare. I decided to leave the potato pieces in the solutions overnight. Method == I will firstly cut up a potato into 6 visually equal small pieces using a scalpel and a cutting tile for safety. I will then use a balance to weigh the mass of the potato before I place it into any solution. Once I have completed the weighing process I will measure 8ml of distilled water (which has a mol dmÂ¯ Â³ of 0) with a measuring cylinder before I place it into a test tube. I will then put one of the sliced potatoes into the 8ml of distilled water and place a bung on the test tube before I put the test tube into a test tube rack. I will be repeat the same process for the other 5 solutions I will use this method twice as I am planning on having 2 experiments running at the same time. The ranges of sugar solutions I will be using are as follows: Text Box: moldmÂ¯ Â³ Solution 1 0.1 Solution 2 0.2 Solution 3 0.3 Solution 4 0.4 Solution 5 0.5 Fair test ===== I feel collecting results using 5 different concentrations of glucose solutions, 6 including water, will be able appropriate for the amount of time I have. Also I feel it is enough results to help me conclude to a reasonable conclusion. I will be running 2 experiments to gain a more accurate result. Also if I gain any anomalous results, by repeating my experiment twice, I will still be able to calculate an average. I will make sure I have a fair test by not changing any of the properties in my investigation apart from the concentration of the solutions. Another way I will keep my experiment fair is by making sure I get each potato slice from the same potato. This is so that I can be fairly certain each piece will have a similar genetic makeup. When weighing the weight of the potato I will be careful not to lean on the balance or the bench. By not doing this there is a risk that I will gain the incorrect mass for the potato. I will be taking care when removing the potato pieces from the solution and I will make sure I weigh the potato as soon as it is removed from the test tube. This will minimise the risk of any changes in temperature affecting the mass of the potato. For example, water loss due to evaporation. I will make sure I label each test tube to ensure they do not get mixed up. I will also need to think of a way to prevent any of the test tubes from losing any liquid. I need to do this because of various reasons, for example, if the temperature of one of the liquid solutions in a test tube increases, some of the solution will be caused to evaporate. This will then cause an unfair test because that test tube will no longer have an 8ml of liquid and will be at a disadvantage from the others. I will keep the temperature the same by using a bung to trap the solution in the test tube. For my own safety I will handle the test tubes with care. I will avoid holding it near my eyes in case of splashing or in case a test tube breaks. I will use a cutting tile to ensure safety when cutting the potato. I shall also make sure I am very careful with the scalpel I will be using. My prediction: My prediction is that the solution with a moldmÂ¯ Â³ of 0.5 will cause the potato to decrease the most in size. I also predict that the potato in the distilled water will become harder. I predict that the mass of the potato piece will decrease as the concentration in the glucose solution increases. I think that as the solution becomes more concentrated the increase in mass will begin to decline. Eventually this will cause the mass of the potato piece to decrease. The higher the solution?s concentration, the lower the mass with increase. The scientific reason beginning when the solution?s concentration of glucose is low the water in the solution on the outer part of the potato cell is greater then the water inside the potato cell. By osmosis occurring the potato cells will take in the water solution. If the solution has a strong concentration of glucose osmosis will happen in reverse. Water will be drawn out of the potato cell into the solution. Results -?? Investigation 1 Concentration of solution (moldmÂ¯ Â³ ) Potato mass before (g) Potato mass after (g) Difference of mass Percentage change in mass 0 0.79 0.99 0.2 23.3 0.1 0.7 0.8 0.1 14.3 0.2 0.66 0.71 0.05 7.8 0.3 0.63 0.66 0.01 1.6 0.4 0.82 0.77 -0.05 -6.1 0.5 0.68 0.57 -0.11 -16.2 Investigation 2 Concentration of solution (moldmÂ¯ Â³ ) Potato mass before (g) Potato mass after (g) Difference of mass Percentage change in mass 0 0.82 0.66 0.22 26.8 0.1 0.76 0.61 0.1 13.2 0.2 0.87 0.66 0.08 9.2 0.3 0.61 0.95 0.05 8.2 0.4 0.69 0.86 -0.08 -11.6 0.5 0.79 1.04 -0.13 -16.4 Graph to show the change in mass for investigation 1 [image] A graph to show the change in mass form investigation2 [image] â?² Text Box: Both of the graphs show that my prediction is right, as the concentration of the solution increases the percentage change decreases. Text Box: Analysis The average difference in weight for distilled water is 0.21 while for the glucose solution of 0.5 moldmÂ¯ Â³ the difference is â??0.12. This relates back to my prediction and proves my prediction to be right. I predicted that the solution with a moldmÂ¯ Â³ of 0.5 would cause the potato to decrease the most in size. Comparing the graphs shows that the potato in investigation 2 in the solution of 0.4 moldmÂ¯ Â³ decreased faster then the potato in the same solution in investigation 1. This could be the cause of unfair testing. It may be because the potato in investigation 2 stayed in the solution of 0.4 moldmÂ¯ Â³ longer then the potato in investigation 1. I also noticed 2 anomalous results in my 2 investigations. The potatoes in the solutions of 0.2 ? 0.3 moldmÂ¯ Â³ decreased quite slowly compared to the others. This is clearly visible on the graph of investigation 2. This could be because the potatoes in the solutions of 0.2 ? 0.3 moldmÂ¯ Â³ are not strong enough to make the potato pieces decrease as much as the potatoes in the solution of 0.4 and 0.5. To prove this I would need to do more investigations. Text Box: Evaluation I could have improved my experiment introducing other variables, such as temperature. Considering whether if the solutions were placed in very low temperatures osmosis would still proceed? Also I could have investigated if the size of the potato affects the speed of osmosis? To gain a more precise result I could have made my timing more accurate. Also it would have been a good idea to repeat my investigation using a series of different potatoes. In case the potato I used was different from normal potatoes in any way. My results could have become slightly inaccurate because some of the potato pieces stayed in the test tube of solutions while I dried and weighed the others. This is unfair because this means some of the potatoes had more osmosis then others. What I should have done was taken them all out dried them and then weighed them. Lucky because it only took a matter of seconds for me to dry and weigh the potatoes, my results werenâ??t affected too badly. Overall I am pleased with my results obtained from my experiment. My results matched up with my predictions and proved fairly accurate as my results relate to the scientific explanation for osmosis. I can tell that my results are fairly accurate as my repeats shows the same trend pattern on the two graphs.

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