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An investigation into the effect on Osmosis by varying the concentration of water

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An investigation into the effect on Osmosis by varying the concentration of water Aim: An investigation into finding out how changing the concentration of the sucrose solution effects Osmosis. Hypothesis: I predict that the less the concentration of sugar is, the greater the mass of the potato will get. This is because Osmosis is the movement of water from a high concentration to a lower concentration, through a partially permeable membrane. And with there being a small concentration of sugar in the solution and a large concentration of water, the water would diffuse into the potato. And the greater the concentration of sugar gets, the smaller the mass of the potato will be. This is because the potato will have a higher concentration of water than the sugar solution, so the water diffuses from the potato into the sugar solution. Apparatus: -Beaker -18 Boiling tubes - Bungs -Salt -Water -Electric Balance -Scalpel -Potato -Cork bore -measuring cylinder Diagram: Variables: Dependent Variables- The dependent variable would be the percentage change in mass of the potato because with the different concentration solutions, osmosis happens differently. ...read more.


0 5 0 0.2 4 1 0.4 3 2 0.6 2 3 0.8 1 4 1 0 5 4. In the six boiling tubes, place a potato into each boiling tube. 5. Pour each different salt concentration into a boiling tube. Seal each boiling tube with a bung. 6. Leave the boiling tubes for 24 hours. 7. Remove the potatoes from the boiling cylinder one at a time and let each potato cylinder damp dry to get rid of extra water drops, and record the mass of each potato cylinder on the electrical balance. 8. Repeat this three more times, from step 1 and 3-10. Results: Molar concentration Initial mass of Potato cylinder (grams) Final Mass of Potato cylinder (grams) Difference in mass of Potato cylinder (grams) Percentage Change in mass of Potato (%) Average Percentage Change (%) Trial 1 2 3 Trial 1 2 3 Trial 1 2 3 Trial 1 2 3 0 0.90 0.78 0.86 1.06 .98 1.02 .16 .20 .16 17.78 25.64 18.60 20.67 0.2 0.71 0.76 0.82 .74 .83 .87 .03 ...read more.


As the molar concentration decreases, the greater the percentage change in mass becomes, this is because with the molar concentration decreasing, the water concentration increases having more water diffusing into the potato than out. From the graph you can see that with the molar concentration being 1, the percentage change in mass is the greatest, because the solution is packed with salt molecules and so much more water diffuses into the solution than into the potato. Evaluation The graph showed in the results is what I predicted would happen, so this suggests that the experiment was fairly accurate. The accuracy of the investigation was adequate, but when each potato was damp dried to get rid of excess water, each potato was not was not necessarily done the same, and they were dried a more accurate way it could improve the accuracy of the experiment. Doing three trails for each solution increased the accuracy, but for at least one trial in each concentration there was an anomalous result, that was that was over 5% greater. ...read more.

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