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Design and carry out an experiment to investigate which concentration of salt solution is needed to store potato so it does not go soggy or shrink.

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Introduction

Osmosis Aim To design and carry out an experiment to investigate which concentration of salt solution is needed to store potato so it does not go soggy or shrink. Hypothesis I think that the following concentration of salt solution, 1M will be the best concentration for storing potatoes because if I store a potato in 0M (distilled water), that is when osmosis works better, so the potato will become turgid and gain mass, whereas if I put it in a salt solution of 2M(strong salt solution), the mass of the potato will decrease and the potato will become soggy because osmosis does take place. So I would estimate that between 0M and 2M, a salt solution of 1M would store the potato without it becoming soggy or hard. Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules but not the solute solution; we say osmosis takes place along a concentration gradient. High Low Concentration concentration Of water of water Molecules molecules Osmosis will turn the potato chip, turgid. Turgidity is when lots of water gets in to the cell. The cell swells up and the cell membrane expands and stretches. Sometimes an organism needs to move dissolved substances from a region where they are in Low concentration, to a region where the dissolved substances are in a higher concentration. ...read more.

Middle

* Drying the potato cylinders of excess water- because if we don't dry the cylinder of excess water so it doesn't get taken into account for the mass of the cylinder at the end. We will shake each cylinder 3 times each. Variable to be changed The variable that I will change in this experiment will be the salt solution. I will use 6 different salt solutions. 0M, 0.5M, 0.75M, 1M, 1.25M and 1.5M. Method 1.Use the measuring cylinder to measure 20ml of each salt solution into film canisters. Label the canisters with the salt solutions. 2. Use the cork borer to make potato cylinders and cut then into 12 pieces each 2g in mass. 3. Record the mass measurement in the table of results. 4. Put 2 potato cylinders in each of the canisters. 5. Leave for 20 minutes. 6. Take each potato cylinder out of the salt solutions and shake it 3 times to remove excess liquid. 7. Re-weigh each potato cylinder and record in the results table. 8. When you have done at least 2 experiments work out the average weight after and complete the table. Results Experiment Concentration (M) Mass before (g) Mass after (g) Difference in Mass Average Difference in Mass Average % difference 1 0 2 2.14 +0.14 +0.125 +6.25 2 2 2.11 +0.11 1 0.5 2 1.87 -0.13 -0.11 -5.5 2 2 1.91 -0.09 1 0.75 2 1.87 -0.13 -0.135 -6.75 2 2 1.86 -0.14 1 1.0 ...read more.

Conclusion

Evaluation I thought the experiment was easy enough to carryout because it was fairly straight forward, however there a few problems, which occurred. The problems I came across were little ones but seemed to affect my graph and results. So If I were to do the experiment again, I would try and improve it so the problems didn't occur. So I found that I couldn't always get the potato chip the right mass of 2g all the time, to improve this I would spend time and concentrate on making sure the potato is the right weight. Also the time, we put the potato chips in for 20 minutes and sometimes the time overlapped the 10-minute barrier so the chip had a bit longer in the solution. So to improve it I would concentrate more. All these mistakes occurred because we were limited for time, if we had more time and didn't have to concentrate on other things, maybe the problems wouldn't have been as big. Due to these problems, they affected the results and the graph. When I looked at the graph I found that 2 points don't sit on the curve of best fit. These anomalous results, a and b, came about because of problems. I think that if we had more scientific equipment, the experiment would have been more accurate and mistakes wouldn't have occurred as much. Also if we had longer time in which to do it, we could of let the potatoes stay in the solution longer so we could see the results over a longer period of time. ...read more.

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