401519-Lab-1-Osmosis-and-Diffusion

401519-Lab-1-Osmosis-and-Diffusion - Lab 1 Osmosis and...

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Lab 1: Osmosis and Diffusion I. Objectives: Demonstrate diffusion across a semi-permeable membrane Measure the effects of various concentrations of solute in the process of osmosis Differentiate between hypotonic, isotonic, and hypertonic environments Measure and calculate water potential Examine the effects of osmosis on plant cells II. Background: Diffusion: The spontaneous movement of molecules or particles in solution along a concentration gradient (i.e. from areas of high concentration to a low concentration) until there is an equilibrium. Osmosis: The diffusion of water molecules through a selectively permeable membrane from a region of low solute concentration to a region of high solute concentration. Equilibrium: A condition in which all influences acting upon it are canceled by others, resulting in a stable, balanced, or unchanging system. Selectively Permeable Membrane: A membrane that allows only certain materials to pass through it by diffusion. Hypotonic: A condition in which the inside of the animal or plant cell has a higher solute concentration than its environment. Osmosis causes a net flow of water into the cell, causing swelling and expansion. This swelling may cause cells without a rigid cell wall to burst. Hypertonic: A condition in which the environment has a higher solute concentration than inside the animal or plant cell. Osmosis pressure causes water to flow out of the cells and causing the cell to shrink. Isotonic: A solution of equal solute concentration that has no net flow of water across the selectively permeable membrane. Water Potential: The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure; the potential energy of
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water to move. Osmotic Potential: The potential for water to move across a selectively permeable membrane, where the osmotic potential of pure water is 0 and any water movement is measured with a negative value. (Also known as solute potential) Pressure Potential: The physical pressure on a solution Osmotic Pressure: The pressure that must be exerted on a solution containing a given concentration of solute separated from a sample of the pure solvent by a membrane. III. Data: A. Table 1: Diffusion Color Glucose Content Time Dialysis Bag Beaker Dialysis Bag Beaker Start cloudy, white yellow brown Yes No 30 minutes light blue near the top, cloudy white at the bottom layer of yellow/orange cloudy Yes Yes B. Table 2: Osmosis Investigation Solution Dialysis Bag Initial Mass (g) 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%
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Osmosis C. Table 3: Potato Cell Water Potential Solution Temperature C Potato Cylinders Solution Initial Final Initial Final Change %Change
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