Osmosis & Diffusion Post Lab

Your post lab will include the following information: Stamped answers to the pre-lab questions Proper data table for Part 1 (dialysis tubing) Proper data tables for Part 2 (one table for russet & one table for sweet) Correct graph for Part 1 with a written summary of the patterns and trends Correct graph for Part 2 (two lines: russet & sweet) with a written summary of patterns and

trends Answer the following analysis question in your lab notebook

Data Analysis Questions For each of the following questions write complete sentences that indicate the original question. 1. Determine the isotonic concentration of both potato tissues and the sucrose solution by

examining Graph 2. Note the point on the curve corresponding to zero change in potato mass. This point will represent the concentration of sucrose isotonic to the potato issue. At this concentration there is no net gain or loss of water from the potato tissue.

2. The osmotic potential (S) of isotonic sucrose solution can be calculated from the molarity of the

solution by applying this formula: S = -iCRT. What is S of a 1.0 molar sucrose solution at 30 °C under standard pressure conditions? Show work!

3. What is the osmotic potential of the sucrose solution found (by your graph) to be isotonic to the

each potato tissue? Show work!

4. Given that the pressure potential (P) of the solutions was zero, calculate the water potential of the solution from the equation for water potential. The water potential of the solution at equilibrium will be equal to the water potential of your potato cells. What is the water potential of both potato cells? Show work!

5. Pure water at standard pressure and temperature has a water potential of 0. Based on the water

potential of both potato cells, if both potatoes were placed into a jar of pure H20, would the potatoes shrink or swell? Explain.

6. If a potato cylinder is allowed to dehydrate by sitting in the open air, would the potato cells’ water

potential become higher or lower? Explain.