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An Experiment to Find the Effect of Time on the Rate of Osmosis

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An Experiment to Find the Effect of Time on the Rate of Osmosis This experiment is to find the effect of seven different lengths of time on the rate of osmosis on potato chips in 0% sodium chloride solutions (distilled water). The rate of osmosis will be measured by the difference in mass before and after the potato chips have been placed in distilled water. Equipment: 14 boiling tubes, 3 boiling racks, 5 potatoes, 1 tissue box, 1 5mm diameter corer, Distilled water 1 Stop clock, 1 measuring cylinder, 1 pipette Pilot Study: Before carrying out the experiment, the decision to put the potato chips in 10% sodium chloride solution or 0% sodium chloride solution (distilled water) had to be made. During the pilot study, three potato chips were placed in distilled water and 3 potato chips in 10% sodium chloride solution. Three potato chips were used for reliable results. All the potato chips were weighed before and after placing them in the solutions for five minutes. The following results were recorded: 10% Sodium Chloride Solution 1 2 3 Mass Before (g) ...read more.


Leave the potato chips in the 0% Sodium Chloride solution for five minutes. Repeat the above seven times. Each time leave the potato chips in the distilled water for firstly 5 minutes, then 10 minutes, 15 minutes, 30 minutes, 40 minutes, 50 minutes and finally 60 minutes. Two potato chips are placed in the 0% sodium chloride solution for one measurement to make sure the results recorded are reliable. For accuracy the potato chips must be put in and taken out of the 0% sodium chloride solution at the exact time specified. When the potato chips are removed from the potato, take the excess liquid off the chip using tissue. The tissues must be sterile as a small amount of osmosis may occur if the tissue is contaminated with a higher percentage of sodium chloride solution. The weighing scales the potato chips are weighed on must be dry and have no original weight of any other substance (for example excess water if the chip has not been adequately dried.) before the potato chips are weighed. ...read more.


The line has flattened off because the cells of the potato cannot hold any more water. Scientific explanation: Osmosis is the movement of water molecules across a selectively permeable membrane from a region of high water potential to a region of low water potential. When osmosis occurs in a plant cell and the plant cell has lower water potential, the cell swells, and become turgid. The cell wall of the plant prevents cells from bursting due to high net flow of water into the cell. As the plant cells gain water potential by osmosis the mass of the plant increases as the water in the cells increases. As the plant cell is left in the These diagrams demonstrate the amount of water gained by osmosis, and how the rate of osmosis affects the mass of a plant. Safety Precautions: When conducting the experiment, the following precautions must be made: * If a boiling tube is dropped, the glass must be cleaned with a dustpan and brush, and gloves. * When using the corer, gloves must be worn, as the corer is sharp. * Throughout the experiment long hair must be tied back and no running in the laboratory. ...read more.

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