11 Diffusion, Osmosis Lab

  1. PART A. Diffusion KMnO4 at 3 temperatures: what is your hypothesis about the effect of temperature on rate of diffusion?

    Record changes at 10 minute intervals for 30 - 60 minutes.

  2. PART B. Dialysis (separation of substances in solution by means of their unequal diffusion through semipermeable membranes):
    1. Tie one dialysis tube
    2. Mix into the tube a stock solution of 5 ml each of 3 solutes:
      • starch,
      • glucose,
      • NaCl.
        Be careful not to spill any of the solutes into the beaker.
    3. After about 1 hour, apply tests: :
      • Iodine (I2KI) for starch,
      • Benedict's solution (in warm water bath) for glucose,
      • Silver nitrate (AgNO3) for NaCl.
    What is your hypothesis about particle size and rate of diffusion? Which molecule(s) should diffuse out of the tube?

  3. PART C. Osmosis
    • Hypertonic, isotonic, hypotonic environments:

    • Use sucrose in 1M and 2M concentrations (1M = 6.02 * 1023 molecules per liter).
    • Measure height of water in pipet in 10-minute intervals.
    • Hypothesis: will the water level rise or fall?
Index Lab notes made Oct 27, 2008 by Peter Chen