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Investigation on Osmosis

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Introduction

Investigation on Osmosis Introduction Since I'm doing coursework involving the process of osmosis, it would probably be useful to state what osmosis is and how it works. A definition of osmosis is the movement of water from a region of high concentration to a region of low concentration through a semi permeable membrane until the concentrations are equal. A semi permeable membrane allows certain small molecules through (such as the water above) but doesn't let larger molecules (such as the sugar above) through it. In the diagram above, the water will move from side B were there is more water to side A were there is less water. This will continue until the concentration of water molecules is equal in both solutions. I learnt this simple example in my biology lesson and used information from the "Biology for You" textbook by Gareth Williams Aim My aim is to find out how osmosis occurs in potatoes at different molar solutions of sugar and water. Apparatus Here is a list of the apparatus I will need to use: > Potato > Sugar solutions (0.2M, 0.4M, 0.6M, 0.8M and 1.0M) > 25cm� measuring cylinder > Scalpel > Test tubes > Cork borer > Cutting tile > Ruler (mm) > Tissue > Digital scale > Funnel Method I need to do my experiment to a fair method, ensuring that the outcome to the experiment is a fair one, and in the hope of not achieving any anomalous results. ...read more.

Middle

This shall cause it to become flaccid. When things are flaccid (opposite of turgid) they have lost fluid, and this should make it shrivel. This is why I think that the potato may shrink in size, and therefore it will shrink. 0.8 This will be the same as 0.6 moles but slightly more to the extreme. Knowing that in my preliminary results it lost weight (the potato in the 0.8 molar sugar solution) I have to explain why and have done in the boxes for 0.6, 0.8 and 1.0 molar solution. This helped me realise that it is likely that all of the molar solutions above 0.4 should lose weight and shrink. More water will be lost compared to 0.6 moles, so it will lose even more weight and shrink even more than 0.6 for the same reasons stated in the boxes for the 0.6 molar solutions. 1.0 I don't want to bore you by repeating the same sort of things so I'll make this brief. For the same reasons as in the above 2 boxes, this one should weigh the least, and should be the shortest. Obtaining Solution 1st Length cm (before) 1st Length cm (after) 2nd Length cm (before) 2nd Length cm (after) 3rd Length cm (before) 3rd Length cm (after) Average change in length (cm) 0.20 2.00 2.00 2.00 1.80 2.00 2.20 0.10 0.40 2.00 2.20 2.00 1.90 2.00 1.80 -0.03 0.60 2.00 2.00 2.00 1.60 2.00 1.80 -0.20 0.80 2.00 1.60 2.00 1.80 2.00 1.60 -0.33 1.00 2.00 1.60 2.00 1.70 2.00 1.60 -0.36 1st Weight grams (before) ...read more.

Conclusion

All these implemented would definitely make the experiment more reliable I think I obtained a suitable range of results and I think they were good enough to help me find a solid, concrete conclusion. On the weight graph, the weight seems to decrease by around 0.20 grams for every time the molar sugar solution increases by 0.2M. To make my conclusion better, I could try to do the experiment for each 0.1 moles of sugar solutions (IE 0.1M, 0.2M, 0.3M, 0.4M etc.) and with distilled water as well. This would let me check to see if these results supported my conclusion and if they did, they might also match my theory that it would decrease by 0.2 grams every 0.2M gained (so 0.1 grams would be lost every 0.1M gained) If I had more time, I would like to do some further work in order to investigate if osmosis would have a different affect on the potatoes if instead of being just 2.0cm long, there would be 2? 1.0cm pieces of potato. I would be interesting to see what the similarities are of the two experiments. That comes to the conclusion of my report into "Osmosis in Potatoes" I hope you enjoyed it, and I hope that you found it more than just satisfactory THIS REPORT WAS BY: JAMIE MORRIS CANDIDATE NUMBER 5094 CENTRE NUMBER 13330 Jamie Morris Biology Coursework ...read more.

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