Open the tubing so that it is not stuck together on itself Knot one end of the

Open the tubing so that it is not stuck together on

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sucrose, permeable to water. Open the tubing so that it is not stuck together on itself. Knot one end of the dialysis tubing and pour your assigned solution into the dialysis tubing until it is approximately two- thirds full. Then seal the open end of the dialysis tubing with a dialysis clamp. Leave approximately ½ in space above the solution when you place the clamp. 3. Rinse the bag in distilled water, wipe the bag and weigh the bag. Initial weight: ______________ g (round to 1 decimal place) 4. Place the dialysis tubing in a beaker and fill the beaker with 200ml of distilled water making sure the water completely covers the dialysis tubing. 5. Every 15 min remove the dialysis tubing from the beaker, gently dry with paper towel to remove the water on the outside, and weigh (as in step 3). You will weigh the dialysis tubing a total of 7 times. Record the weight gain (loss) (in grams) on Table 1. The weight gain (loss) = current weight – initial weight Table 1: Lab group results 15 min 30 min 45 min 60 min 75 min 90 min ___% sucrose weight gain (g) 6. Report your group’s weight gain (loss) results on the board and record the averaged class results in Table 2 as their results become available. Table 2: Average weight gain of dialysis tubing over time Time (min) 0% sucrose 10% sucrose 20% sucrose 30% sucrose 40% sucrose 50% sucrose 15 30 45 60 75 90 FIGURE 1: Comparing rates of osmosis: average total change in weight vs. time Using the data in Table 2, plot the average class results of your group’s solution on the graph below, as well as the average results for one other solution that differs by at least 3 concentrations from the solution you experimented on. (i.e. If you were assigned the 40% solution, you would use the 10% or 0%
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solution for comparison.) Draw a line connecting the values for each solution, making sure to use a different color or symbol for each line. Label each line with the solution it corresponds to. Part I Questions: 1.Which of the two graphed solutions showed the fastest rate of osmosis? Hint: The rate of Weight (g) 0 15 30 45 60 75 90 Time (minutes)
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2.Which of the two graphed solutions did you expect to have the fastest rate of osmosis and why? 3.Did your lab group’s results match what you expected? If not, how were they different and why do you think the discrepancy occurred? II. RBC Membrane Permeability and Osmosis (modified from ) A. Osmosis Across the RBC Membrane In this experiment, we will place RBCs in a 1.0 M sodium chloride (NaCl) solution, and 0.15 M NaCl solution, and distilled water. Sodium chloride ionizes into Na+ and Cl- ions when in solution, and these ions are too charged to freely diffuse through the RBCs plasma membrane. Only water can easily pass into or out of the cells. Based on your results, you will be able to determine whether each solution is hypotonic, isotonic, or hypertonic to the cell. 1. Set-up 3 test tubes labeled 1.0 M NaCl, 0.15 M NaCl
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  • Fall '15
  • smith
  • Osmosis, Semipermeable membrane

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