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# Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration.

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Introduction

Osmosis coursework Introduction Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. The aim of the investigation is to find the variables that affect the rate of osmosis and how they affect the rate of reaction. The variables that affect the rate of reaction of osmosis are, * The surface area of the object, * The concentration of the solution, * Temperature of the experiment Surface area If the surface area of the object is larger then more molecules can pass through the semi-permeable membrane. This will ultimately increase the rate of reaction. Small surface area Large surface area Concentration If the concentration of the solution is high then it will contain more molecules and so the rate of reaction will be shorter. Low concentration High concentration Temperature of the experiment Generally the higher the temperature, the less time it takes for a reaction. But with living cells there is a point at which the cell will be denatured therefore the rate of reaction will be altered, as the cells are no longer functioning. ...read more.

Middle

I think this because as the salt solution increases in concentration, water will leave the chip through the process of osmosis to create equilibrium therefor the size of the chip will decrease. Apparatus Potato (peeled), Scalpel/knife, White tile, Forceps, 5 petri dishes, Distilled water, Salt solutions 0.1m, 0.2m, 0.5, and 1m Cork borer (7mm diameter) Diagram Method Label the lids of the 5 petri dishes with the concentration of the salt solution for that particular dish. Put 50ml of the solution marked on the lid of each dish into its petri dish. Put the lids on the dishes. Cut 25 chips using the cork borer so that each chip is exactly the size of the others being sure to measure them carefully. Place 5 chips in each dish so that they don't touch each other and place the lid on the dishes. Leave each dish for 30 minutes. After 30 minutes measure carefully and record the dimensions of each chip. Table of results Solution in petri dish Dimensions at start (cm) Dimensions at finish (cm) Average dimension Distilled water 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 0.1m 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 1?0.7 0.2m ...read more.

Conclusion

Having the results which backs up my hypothesis, proves that this investigation was fully accomplished, and was an achievement. Evaluation Using more types of molar salt solutions would have helped us obtain better results, and more accurate results, so that we can make sure the results are totally correct. Experimenting with one set for a longer period of time, for each set, would lead us to better results, because the osmosis action would reach its maximum capability, and therefore tell us how much water could be transferred for each solution. Repeating the same tasks many other times wouldn't have been very useful, since we had already done the result 5 times, and ALL the results were reliable. Although my experiment went well overall and I obtained some accurate and reliable results I feel that there could be some adjustments made to the method. If I could repeat the experiment again I would use chips with larger dimensions, as measuring the chips was very difficult. Secondly I would have like to of left the chips for longer than 30 minutes as I feel the chips may have shown a greater difference in their dimensions. Lara Lavelle-Langham ...read more.

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Dialysis Bag Final Mass (g) Change in Mass (g) % Change in Mass Water 16.99g 18.50g +1.51g +8.89% 0.2 M 25.13g 25.69g +0.56g +2.23% 0.4 M 25.48g 27.46g +1.98g +7.77% 0.6 M 13.68g 14.27g +0.59g +4.31% 0.8 M 27.26g 30.12g +2.86g +10.49% 1.0 M 23.25g 25.92g +2.67g +11.48% Osmosis Temp Temp Mass (g) Mass (g)

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