4.9 To conduct any activity to demonstrate osmosis
Teacher Notes
Apparatus required per class of 24 students
Distilled water
Sucrose solution
Beakers
24
Glass rods
24
Small funnels
12
Visking tubing (40 cm) 24
Scissors
12
Ruler
12
Labels
24
Electronic balance
3
Paper towels
Advance preparation
o Prepare sucrose solutions
Advance chemical preparation
(a) 80% w/v sucrose solution
o Dissolve 80g of glucose in distilled water and make up to 100 ml with distilled water.
Expected outcome of experiment
o The visking tubing containing the distilled water shows no change in mass (i.e. it has
not gained or lost water).
o The visking tubing containing the 80% sucrose solution will have filled with water so
that it has gained mass. This is due to the water entering the tubing due to osmosis.
Disposal and post-experimental work
o
Excess sucrose solution can be stored for 1-2 weeks.
Biology SLSS 2009
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4.9 To conduct any activity to demonstrate osmosis
Student Notes
Apparatus required per group
o 2 x 40cm Length of visking tubing
o Ruler
o 2 Beakers
o Label
o 2 Glass rods
o Distilled water
o 2 Small funnel
o Sucrose solution
o Scissors
o Paper towels
o Electronic balance
Assembled apparatus
Method
1. Soften two 40 cm strips of visking tubing by soaking them in water.
2. Tie a knot at one end of each strip.
3. Using a clean funnel, half-fill one piece of tubing with sucrose solution and the
other with distilled water.
4. Eliminate as much air as possible from the tubes and tie a knot at the open end of
each tube.
5. In the case of each tube, tie the two ends, making a loop.
6. Wash off any excess sucrose solution from the outside of the sucrose tube and
pat dry both tubes with the paper towels.
Biology SLSS 2009
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7. Observe and record the turgidity of each tube.
8. Find the mass of each tube and record.
9. Suspend the tube containing the concentrated sucrose solution, by means of a
glass rod, in a beaker of distilled water and label it ‘sucrose solution’.
10. Similarly, place the tube containing the distilled water into a second beaker of
distilled water and label it ‘distilled water’. This acts as the control.
11. Allow the tubes to stand for at least 15 minutes.
12. Remove the tubes and dry as before.
13. Observe and record the turgidity of each tube.
14. Again find the mass of each tube and record.
15. Replicate the investigation or cross reference your results with other groups.
16. At the end of the experiment, clean all of the equipment and replace it in its
correct place.
Results:
Tube contents
Turgidity at
Turgidity after
Mass at start
Mass after test
start
test period
(g)
period (g)
Sucrose solution
Distilled water
Conclusion/Comment
Biology SLSS 2009
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