Diffusion and Osmosis Through Nonliving Membranes

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LAB REPORT Diffusion and Osmosis through Nonliving Membranes BIO 116-02 02/14/13 Introduction: The following experiment provides information on the movement of water (osmosis) and solutes (diffusion) through differentially permeable membranes called dialysis sacs. Dialysis sacs have pores of particular size not as selectivity of living membranes depends on more than just pore size, but using the dialysis sacs allowed us to examine selectivity due this factor. So this lab experiment showed us visually, how diffusion and osmosis took place and we have been proved our hypotheses by few tests such as Benedict’s test, AgNO3 test, also via testing total weights of dialysis sacs after experiments. Materials and methods: We had four dialysis sacs, small funnel, 25-ml graduated cylinder, fine twine and four beakers (250ml). Solutions: distilled water, 40% glucose solution, 10% NaCl solution and 40% sucrose solution. Also we had equipment and supplies for Benedict’s test and AgNO3 test, such as Benedict’s solution, silver nitrate and beaker with boiling water. 1. Previously number marked beakers half feel with distilled water except #2, which has to be filled with 40% glucose solution. 2. Using the funnel, fill dialysis sacs with approximately 20ml of the specified liquid. Sac #1 and #2 filled with 40% glucose solution, sac#3 – 10% NaCl solution and sac #4 filled with 40% sucrose solution. They have to be weighted (data chart on table 1) and then each of the sac dropped into particular corresponding beaker. Sac #1 placed into beaker #1 with distilled water, sac #2 placed into beaker #2 with 40% glucose solution and so forth. 3. Before analyzing, we had to allow sacs to remain undisturbed in the beaker for 1 hour. 4. After 1 hour we boiled a beaker of water on the hot plate (for Benedict’s and AgNO3 test). 5. We took all of the dialysis sacs

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