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Diffusion and Osmosis lab Results: Figure 1a-rate of weight change in 15 min intervals of each concentration. The first tube showed very little weight change. However all other tubes show a greater change the concentration could be the factor that determines the permeability of the sucrose. The sucrose molecules are too large to pass through. Figure 1b- sucrose concentration determines the weight change. In this case based on our results as concentration increases the percent weight change is decreasing. Discussion:
The purpose of this lab was to observe and analyze various factors that affect the process of diffusion and osmosis. We observed that the permeability of the dialysis tubes, which is our permeable “membrane”, depends on the concentration of the sucrose, not only is it important how permeable the tube is but also the rate at which osmosis is occurring. Water moves across the selectively permeable membrane of the dialysis tubing much easier than sucrose sugar does. The water moved to reach equilibrium between the solutions. Sucrose must be too large a molecule to pass through the membrane quickly.
That was visible based on the observations for the first tube at 1. Unfortunately our observations can not be too accurate since we ran out of 40% sucrose to do any observations and analysis on the permeability of the membrane when tap water is inside as the solute and the sucrose as the solvent. Questions part I: What relationship exists between the concentration of sucrose and the rate of osmosis? -The rate of osmosis depends on the concentration of sucrose the water will move from a lower concentration to a higher concentration.
What factors may have contributed to any errors in measurements? The factors that could have contributed to any errors in measurements, are incorrect pipetting, gives you less or more of the required amount needed in the dialysis bags, and will change the mass of each bag that is to be recorded. The balances have to be clean in order to give accurate measurements. Questions Part II: What is the concentration of the unknown sucrose solution? Use the graph to determine the concentration of the unknown sucrose solution. 6% Based on your knowledge of osmosis, explain why certain dialysis bags gained weight while others lost weight. -Some bags lost or gained weight because water diffuses out of the bag to the highest water potential which is inside the bag, forcing the water out. For most freshwater organisms, from the single-celled Paramecium sp. to the multi-cellular fish, internal salt levels are maintained far above that of the outside water. Describe in which direction water will move for these organisms.
Why could this be a problem and how might they deal with it? -For some organisms such as the paramecium, has an organelle called the contractile vacuole. The contractile vacuole expands when water enters, the water will go inside, the paramecium and contracts periodically to expel the excess water out of the paramecium. The excess water can causes the central vacuole to burst so it need to go through a process is called osmoregulation. Which gets its name from the process of osmosis. ———————– [pic] [pic] [pic] [pic]