Diffusion Osmosis Lab

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Diffusion Osmosis Lab (Title) Questions: 1. What size of molecules (monosaccharide vs polysaccharide) can diffuse through a semi-permeable membrane? 2. How will the concentration of sucrose within the dialysis tubing affect the rate that water diffuses through a semi-permeable membrane? 3. How will the concentration of sucrose in water affect the amount of water that diffuses into or out of the potato cells and thereby change the mass of the potato cells? Hypotheses: 1. If the solution inside the dialysis tubing is hypertonic to the water in the beaker, then the glucose will diffuse out of the bag, and the water will diffuse into the bag, however the starch will remain in the bag. This will occur because the water and glucose are small enough to diffuse out of the pores in the dialysis bag, but the starch molecules are too large to fit through 2. If a solution is very hypertonic, then the most amount of water will diffuse across the semi-permeable membrane into the dialysis tubing. This occurs because the higher concentration of solute, the more water it takes to reach equilibrium, thus, the faster rate of osmosis. 3. If we place the potato in a sucrose solution with a similar solute concentration as a potato, then the least amount of water will diffuse into or out of the potato cells. This occurs because this scenario will be initially closest to an isotonic solution, allowing us to determine the solute concentration of a potato. Materials: * Knife/ Cork Borer * Seven 30 cm pieces of Dialysis tubing * Thirteen 250 mL Beakers * 15% Glucose Solution * Glucose Test Strips * 1% Starch Solution * Distilled water * Lugol’s solution * 25 mL of: * .2 M sucrose * .4 M sucrose * .6 M sucrose * .8 M sucrose * 1 M sucrose * Paper Towels * Clock * Potatoes * Plastic
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