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Planning Experimental Procedures - Osmosis Experiment.

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Introduction

OSMOSIS EXPERIMENT Planning Experimental Procedures It is known that liquids move from a low concentrated area to a higher concentration. This is more commonly known as osmosis. The liquids try to balance out the concentration. Osmosis occurs commonly in cells. Substances such as water are diffused into the cell until the concentration from the outside and inside of the cell are as equal as possible. The aim of the investigation is to see if increasing the surface of a potato tube will affect how fast the process of osmosis takes place for the movement of water in or out of the potato. The apparatus and resources that are going to be needed to go through with this experiment is: distilled water, Electric scales, Potato, cork borer, knife, Measuring cylinder, test tubes, I first had to get a potato. I than used a cork borer to cut out about six potato cylinders. For safety, i did not hold the potato in my hand while cutting out the cylinder but left it on the desk. Each cylinder had to be the same size and because we got a small potato i cut out six cylinders at the length of 3cm long, they all had to be 3cm long otherwise it would not have been a fair test. Not every cylinder came out 3cm long and so we had to use a knife to cut it down to size, care was taken whilst using the knives. ...read more.

Middle

If you look at the last column, where the potato cylinder is cut into ten parts, the weight increases a lot and the percentage increase is higher than if you cut it into two. We did the same experiment a third time, just to make sure that we are getting fair results, and this is what we got: Number of pieces Weight before (g) Weight after (g) Percentage increase (%) 1 0.92 1.12 20 2 0.82 1.05 23 4 0.88 1.11 23 6 0.74 0.96 22 8 0.82 1.13 31 10 0.95 1.24 29 This experiment also has a couple of anomalous results but if you do not look at these anomalies, you can clearly see that if you increase the number of pieces, you increase the percentage increase. This last set of results is the average percentage increase of weight, in the potatoes. I found out the average by using the three sets of results above. Number of pieces Average percentage increase (%) 1 36.7 2 43.3 4 50.7 6 59.0 8 47.3 10 64.7 Analysing Evidence & Drawing Conclusions After doing the experiment and examining the results I can now say for sure that my prediction was right, that the more pieces there are the more water the potato will take in and that if I double the surface area exposed in water, then the speed of osmosis will also double. ...read more.

Conclusion

This pressure exerted on the chip could have either caused small bits of it to break off. It could have also caused some of the water to be squeezed out of the cells of the chip, though probably didn't have a drastic effect on the mass. The one anomalous result that I collected could have been because of water being evaporated from it and because of the force I used to get it out of the test tube. Apart from this one anomaly we can still make a firm conclusion that if you increase the surface area of the potato you will increase the amount of water that will be taken in, therefore if you double the surface area the percentage increase, of weight, should also double. How I would make my experiment better, would be that when I took the chip out I would use my finger and wipe the surface, making sure that there wasn't too much water on the outside affecting the mass. To make sure that there was as little evaporation as possible, I would do my experiment nearer to weighing machine and I would have a fan working next to my experiment, this would make the air around the chips as cool as possible. Also, the way I would remove my chip from the test tube would be that I would pour the content of the test tube into a sink, but catching the chip in my hand. This way I wouldn't put so much force on it. HAMMAD NAVEED ...read more.

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