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Osmosis, Aim: To investigate the movement of osmosis through a selectively permeable membrane, in this case potato.

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Introduction

Osmosis Aim: To investigate the movement of osmosis through a selectively permeable membrane, in this case potato. Introduction We are carrying out an experiment to try to prove the theory of osmosis, which is the overall flow of water from a dilute concentration to a higher concentrated solution through a semi-permeable membrane. In this experiment I will be analysing the change of mass of potato slices when placed in a sucrose solution. Science theory Osmosis in this case is the diffusion of water through a semi-permeable membrane, which, in this experiment is the potato cell from a low concentration to a high concentration of sucrose solution. If two solutions of different concentrations are separated by a semi-permeable membrane which is permeable to the smaller solvent molecules but not to the larger solute molecules, then the solvent will tend to diffuse across the membrane from the less concentrated to the more concentrated solution, this process is called osmosis. More water molecules move away from an area of higher concentration of water molecules. This is a type of diffusion. Diffusion is when molecules in gases and liquids move about randomly. They collide with each other causing them to change direction. ...read more.

Middle

Solution (ml) Water (ml) Mass (g) Final Mass (g) Change in mass 1.0 40 0 3.52 1.84 1.72 0.75 30 10 2.81 1.82 1.01 0.5 20 20 2.98 2.01 0.98 0.25 10 30 3.41 3.04 0.41 0 0 40 3.38 3.92 -0.42 Method 1. We will take one average sized potatoes and use a core borer to get 18 potato chips. 2. We will do this on a white tile to make sure we do not damage the tables because the core borer is extremely sharp. 3. Thereafter we will use a scalpel to cut each chip precisely to 3 cm long using a 30cm ruler. 4. We will then use a test tube rack and place 5 test tubes in it and label them: 0 molar, 0.25 molar, 0.5 molar, 0.75 molar and 1 molar. 5. Using a measuring cylinder I will measure the different amounts of sucrose solutions and water that needs to be placed into the 100ml beakers. 6. I will place one sticker label on all the beakers used to identify the different amount of solutions in each beaker. 7. But before pouring in the solutions in the 100ml beakers I will weigh the chips each to get their initial mass in grams and record the results onto a table. 8. ...read more.

Conclusion

Also I would make sure that the potatoes I use will not be crippled or dodgy potato, I will try to get a big accurately circular shaped potato so that the potato chips would not have all the slightly crooked shapes. Also I would try to clean and wipe off the bits of water that were still on the weighing scale and make sure that it is dry to make sure that these water particles do not alter my results. These improving methods that I could use and the problems we had, suggest that the results were reliable but could have been a lot more reliable if I were to improve the experiment with the ideas that I gave above. My results table above shows the two outliers highlighted and that is all the outliers I received and the outliers both reflected on my graph. Also, my graph showed me that my results were reliable as I received several small error bars, increasing the reliability; also I noticed the line of best fit changing at the end of the graph, this was showing me that plasmolysis occurred in my potato slices. Plasmolysis is the loss of water from a cell, in this case a potato cell, causing it to contract and deform. ?? ?? ?? ?? Zubbair Ghani 11W ...read more.

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