Osmosis Investigation Question What is the concentration of solutes in potato cells? When a dilute solution is separated from concentrated solution by a partially permeable membrane, water diffuses across the membrane from the dilute side to the concentrated side. This process is called Osmosis.A partially permeable membrane is porous but allows water to pass through it more rapidly than dissolved substances. Since dilute solutions contain more water molecules than concentrated solutions, there is a diffusion gradient, which favours the passage of water from the dilute to the concentrated solution.The factors that have an affect on osmosis  Concentration of the sugar solution ...view middle of the document...
I used solutions 0% , 2% , 4% , 6% , 8% , 10% , 12% , 14% , 20%.Solutions % Length mm Diameter mm Mass grams Length After mm Diameter After mm Mass After mm Time minutes 0% 10.32 8.3 0.54 11.68 8.51 0.71 6 mins 2% 10.45 8.3 0.49 11.52 8.45 0.68 6 mins 4% 10.6 8.3 0.56 10.97 8.42 0.62 6 mins 6% 10.1 8.3 0.48 10.3 8.35 0.56 6 mins 8% 10.81 8.3 0.6 10.71 8.3 0.59 6 mins 10% 10.72 8.3 0.54 10.68 8.29 0.53 6 mins 12% 10.95 8.3 0.61 9.89 8.24 0.52 6 mins 14% 10.13 8.3 0.58 9.72 8.13 0.47 6 mins 20% 10.56 8.3 0.57 8.61 7.95 0.42 6 mins I can see from my preliminary tests that 6 minutes works very well because I have a wide range of results.All of the concentrations that I used worked very well, so I can choose a wide range of my investigation. I will use 0% , 4% , 8% , 12% and 20%.Prediction I predict that when I increase the concentration of the sugar solution above the concentration of the potato cell, it will decrease in size. This is because there will be a higher concentration of sugar outside of the potato. The water inside the potato will pass through the partially permeable membrane to the solution in the beaker. Therefore the potato will shrink. However, when I use a concentration of 0% , the potato piece will increase in size. This is because the concentration of the potato cell will be higher than that of the 0% (distilled water). Therefore, the water will travel outwards through the partially permeable membrane into the 0% (distilled water).When a substance such as sugar dissolves in water, the sugar molecules attract some of the water molecules and stop them moving freely. This, in effect, reduces the concentration of water molecules.Below, in the diagram, sugar molecules on the right have "˜captured' half of the water molecules. There are more free water molecules on the left of the membrane than on the right, so water will diffuse more rapidly from the left to right across the membrane than from right to left.The partially permeable membrane does not act like a sieve, in this case. The sugar molecules can diffuse from right to left but, because they are bigger and surrounded by a cloud of water molecules, they diffuse more slowly than water. (D.G Mackean) The water potential of a solution is a measure of whether it is likely to lose or gain water molecules from another solution. A dilute solution, with its high proportion of free water molecules, is said to have a higher water potential than a concentrated solution, because water will flow from the dilute to the concentrated solution (from a high potential to a low potential). Pure water has the highest water potential because water molecules will flow from it to any other aqueous solution, no matter how dilute.Osmosis. Water will diffuse from the dilute to the concentrated solution through the partially permeable membrane. As a result, the liquid level will rise on the left and fall on the right. (D.G Mackean) Method Cut some cylinders out of a potato, each with 8.32mm diameters....
