Lab Report: Diffusion and OsmosisIntroduction:Atoms and molecules are constantly in motion. This kinetic energy causes the molecules to bump into each other and move in different directions. This motion is diffusion. Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration. This will occur until the two areas reach a dynamic equilibrium.Osmosis is a special kind of diffusion in which water moves through a selectively permeable membrane. A selectively permeable membrane allows diffusion for only certain solutes (the substance being dissolved) and water, the most common solvent (a dissolving substance). The most common selectively permeable membrane is the cell membrane. Water moves from an area of high water potential to an area of low water potential.There are three relationships that can occur between two solutions. When two solutions have equal solute concentrations, they are isotonic and no net movement of solute occurs. There is also no net movement of water. If the two solutions differ in solute concentrations, they will either be hypertonic or hypotonic. The hypertonic solution has a lower concentration of solute. Water will move out of a hypertonic solution, while solute will move in. The hypotonic solution has a higher concentration of solute, therefore has less water. This solution will gain water, while losing solute. This movement between the hypotonic and hypertonic solutions will continue until the point of dynamic equilibrium is reached.Materials:String or rubber band wax pencil30% glucose solution starch solutionI2KI solutionBenedict's reagentHot plate300mL beaker 1/3 filled with waterHandheld test tube3 standard test tubeDisposable transfer pipette2 400 mL beakers to hold dialysis bag30-cm strip of moist dialysis tubingProcedure:Prepare the dialysis bag with the initial solutions.Leave the bag in the beaker for about 30 minutes.After 30 minutes carefully remove the bag and stand it in a dry beaker.Record in table 3.1 the finial color of the solution in the bag and the final color of the solutions in the beaker.Preform the Benedict's test for the presence of sugar in the solution.Review your results in table 3.1 and draw a conclusion in the discussion section.Results:
Solution source
Original contents
Original color
Finial color
Color filter Benedicts test
Bag
-4mL pipette of glucose
-4mL of starch
Milky white/ clearish
Dark purplish
Solid yellow
Beaker
-150mL of water
-Iodine(potassium)
Yellow
Goldish
clear
Control
Water
Clear
Clear
Clear
Conclusion:In this experiment we observed that the concentration inside the dialysis bag (the starch) is the biggest molecule (hypertonic) therefore the iodine, the smallest molecule (hypotonic) is trying to enter the dialysis bag to establish the equilibrium causing a color change to the solutions.
