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Properties of an Artificial Membrane: Diffusion and Osmosis

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Introduction

Properties of an Artificial Membrane: Diffusion and Osmosis Purpose- Is to gather enough evidence to prove that osmosis and diffusion occur in these types of membranes, this is done by using a selectively permeable membrane called dialysis tubing. Hypothesis- Osmosis and diffusion will continue until equilibrium is reached and net movement will no longer occur. Solute size and concentration gradient across the selectively permeable membrane will effect diffusion. Materials- please refer to transport across semi-permeable membranes: diffusion and osmosis laboratory exercise hand out. Procedure: please refer to transport across semi-permeable membranes: diffusion and osmosis laboratory exercise hand out. Observations: Table A: Time Dilute Lugol's solution in beaker Glucose and Starch solution in dialysis tube Initial Observations Clear yellow solution/ color changed into blue Clear After 10 minutes More yellow than before/ reacted with ...read more.

Middle

The iodine diffused through the tubing, but the molecules of starch/glucose solution were too large to diffuse through the tubing. Iodine, which is a fluid and has very small molecules, was able to diffuse through the dialysis tubing and reach an equilibrium on the inside and outside of the tubing. This is proven by the increase in the size of the tubing from the initial mass of 14.66 g to a final mass of 15.74 g. However, sucrose and starch are macromolecules, so they were too large to diffuse through the tubing. This was proven by the benedicts test of the outside area, it came up negative, while the test of the tubing fluid came up slightly positive. ...read more.

Conclusion

Another possible source of error would be not leaving the solutions for the amount of time required, possible way to improve this would be keeping a watch nearby at all times. Ways to improve this lab would be to add more than 5 drops of Lugol's Iodine solution to the distilled water, therefore a more vivid observation could be recorded. Another way to improve this lab would be to extend the time of observation and then that would give time to collect clear and more accurate evidence. Conclusion: Osmosis is the diffusion of water molecules through a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration. Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. ?? ?? ?? ?? Etran Bouchouar 5/1/2007 ...read more.

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