Osmosis And Diffusion Lab

Osmosis and Diffusion

Title: Diffusion and Osmosis AP Lab 1

Purpose: The purpose of this activity is to determine the effects of a selectively permeable membrane on diffusion and osmosis between two solutions separated by a membrane.
Hypothesis:
Procedures: In lab manual
Material: In lab manual
Background Information:
Data:

Table 1
Diffusion of glucose and iodine.

| Color | Glucose | Time | Dialysis Bag | Beaker | Dialysis Bag | Beaker | Start | | | | | 30 minutes | | | | |

Table 2
Osmosis Investigation – Water gain by dialysis bags

Solution | Dialysis BagInitial Mass (g) | Dialysis BagFinal Mass (g) | Change in Mass (g) | % Change in Mass | Water | | | | | 0.2 M | | | | | 0.4 M | |
| | | 0.6 M | | | | | 0.8 M | | | | | 1.0 M | | | | |

Table 3
Potato Cell Water Potential- Gain and loss of water in different environments.

| Solution Temperature | Potato Cylinder | Solution | Initial Temp | Final Temp | Initial Mass (g) | Final Mass (g) | Change in Mass (g) | % Change in Mass | Water | | | | | | | 0.2 M | | | | | | | 0.4 M | | | | | | | 0.6 M | | | | | | | 0.8 M | | | | | | | 1.0 M | | | | | | |

Plant Cell Plasmolysis

Cells in Distilled Water |

Cells in 15% NaCl

|

Conclusion:
1. Create a Venn diagram comparing osmosis and diffusion.
2. Part A of the experiment was a demonstration of diffusion. Give an example of diffusion occurring in the setup. Do you think osmosis occurred in this part of the experiment? If yes, explain why you believe this to be.
3. Did the dialysis tubing serve as a selectively permeable membrane? Explain your answer.
4.
In part B, what caused the mass of the dialysis bags to change? Was there more or less water in the dialysis bags at the conclusion of the experiment? Explain.
5. Was the distilled water in the beakers hypertonic or hypotonic in relation to the sucrose solutions found in the dialysis bags?
6. Suppose the dialysis bags were placed in beakers containing a 0.6 M sucrose solution as opposed to distilled water. How do you think your results would change? Sketch a graph below to show how the mass of each of the bags would be affected.
7. Study the graph you have plotted for part C of the experiment. What is important about the point where the best fit line crosses the X-axis? What is the concentration of sucrose in your potato?
8. Fill in the blanks in the statement below using the following list:
Net gain, low, hypertonic, exit, osmotic, enter, less, hypotonic, high, more, net loss, isotonic (not all words are used) If a cell is placed in a ________ solution, it has _____________ solute in solution than the surrounding fluid, and will therefore experience a __________ of water to its surroundings. This cell has ______________ water potential since there is a great deal of _______ pressure causing water to leave the cell. Conversely, a cell sitting in a _______ solution has a ______ water potential, and since it will experience a ________ of water, there will be little osmotic pressure causing water to _________ the
cell.
9. Consider what would happen to a red blood cell (RBC) placed in distilled water:
a) Which would have the higher concentration of water molecules?
Distilled H20 RBC
b) Which would have the higher water potential?
Distilled H2O RBC
c) What would happen to the red blood cell? Why?
10. What is plasmolysis?
11. Why did the onion cells plasmolyze?
12. In the winter, grass often dies near roads that have been salted to remove ice. What causes this to happen?
13. What are the effects on cells when they are placed in a hypotonic solution, hypertonic solution, and isotonic solution?
14. Why can’t humans drink salt water for hydration?