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How Osmosis affects Potato chips in different concentrations.

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Introduction

How Osmosis affects Potato chips in different concentrations: Background: Osmosis is the movement of water molecules across a partially permeable membrane from a region high water concentration to low water concentration. A partially permeable membrane is a membrane with tiny holes in so small that only water molecules can pass through. When you place a potato chip in a salt or sugar solution, then if the potato has higher water potential some of the water will diffuse into the Sal solution which will cause the chip to lose weight. However the water amount is in the salt solution is larger then the water will be diffused to the potato chip thus causing the chip to gain weight. If the water amount is equal then the weight of the chip will not change. In a high concentration of water the amount of solute (e.g. sugar) is low. This could be called a weak or dilute solution. In a low concentration of water the amount of solute (e.g. sucrose) is high. This could be called a strong or concentrated solution. When two such solutions are divided by a semi-permeable membrane the water will move from the area of high concentration to the area of low concentration, until both sides have reached equilibrium. Plant cells always have a strong cell wall surrounding them. When they take up water by osmosis they start to swell, but the cell wall prevents them from bursting. Plant cells become "turgid" when they are put in dilute solutions. Turgid means swollen and hard. The pressure inside the cell rises and eventually the internal pressure of the cell is so high that no more water can enter the cell. This liquid or hydrostatic pressure works against osmosis. Turgidity is very important to plants because this is what make the green parts of the plant "stand up" into the sunlight. When plant cells are placed in concentrated sugar solutions they lose water by osmosis and they become "flaccid." ...read more.

Middle

Top Pan Balance * Beakers * Knife * Ruler * Labels * Paper Towels * Measuring Cylinder Method: in order to do the following experiment I will be following this procedure: 1. Collect all the apparatus. 2. I will carefully slice twelve bits of potatoes at the measurement of 3cm and weigh them at 3grams on the top pan balance. 3. I will label all the test tubes so the solutions don't get mixed up. 4. Using a measuring cylinder I will pour all the concentrations at 30ml in the correct tubes. 5. After placing the potato in the tubes I will cover them with cling film and leave them for 24hours. 6. 24hours later I will remove all the cling film and dry the potatoes with a paper towel. 7. I will then measure all the potatoes and record the results in a table. The experiment must be repeated twice: the experiment may look like this: Preliminary Work: Prior to this experiment I did an experiment to help with a prediction and also to help indicate a number and range for the main experiment. The results from this experiment had many errors occur due to humanly errors. Whilst doing the experiment we didn't dry the top pan balance before we measured the chips and we also forgot to dry the potato chips. This caused all are results to be inaccurate also we decided to vary our solutions more. When we did out preliminary experiment we only used 2%, 8%, 10% and distilled water. This didn't give us a good range of results and caused the whole experiment to weaken. We also tried different masses for the potato chips and came to the conclusion three grams would be adequate. From the preliminary experiments we decided to vary the solutions more so we could monitor the way osmosis works clearer. So in our real experiment we decided on 3grams for the potato chips and try the 4% and 6% solutions as well. ...read more.

Conclusion

Reliability: The results were reliable to take a reasonably accurate result. However the steps above (1, and 2) would produce an even more accurate result. Further work: To extend this experiment it could be repeated exactly as before. However this time results at the morality levels. This would produce much more accurate results. Other variables in the experiment could be changed for example instead of changing the weight of the potato the species of the potato could be changed. For example new potatoes, King Edwards etc could be used. Also the shape and size could be changed. However this would not affect the results much. This is because the variable would only change the rate of osmosis because of a different weight and size. Temperature could also be changed for example the samples could be placed in different water baths and brought up to different temperatures to see if temperature played its part in the osmosis of potatoes. 5 sets of 5 potatoes could be placed in water baths at 10oC, 20oC, 30 oC, 50 oC and 60 oC. Then leave them for 24 hours making sure all the variables in the first experiment still apply however just using one molar solution. Then after 24 hours re-weigh the samples and record the result. I would expect that at high temperatures the potato samples would osmosise the most. This is because at high temperatures the solutions water molecules would move faster and therefore equal the concentration faster. A preliminary experiment could be set up beforehand to find out how long the experiment should be kept going because if the concentration of the potatoes equalises then the weight of the potatoes will be almost exactly the same. I could extend my coursework by testing the same brand of chip using a different substance. By this I mean using a different thing instead of sugar, i.e. salt or coffee or even vimto. Then I could find out whether osmosis occurs differently with different things diluted in the water. I could even use different vegetables. ...read more.

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