Diffusion practical visking tubing 1

Practical to Investigate Diffusion and Osmosis

Collect the following equipment:

1x beaker
1x length visking tubing
1x pipette
1x pair safety glasses

Instructions – always wear safety glasses!
1. Fill your beaker ¾ full with water

2. Tie a knot in one end of your visking tubing

3. Using your pipette, transfer some concentrated sugar solution to the inside of the visking tubing, leaving enough space to tie a knot in the open end

4. Add a few drops of red food colouring to the inside of the visking tubing

5. Tie off the open end of the tubing

6. Place the tubing carefully inside the beaker and leave for ~ 1 hour

Results and conclusion
What did you notice after half an hour had passed? Record your observations here and explain why you thought they happened.

The water in the beaker had moved through the visking tubing against a high to low concentration gradient, as this is the movement of water through a gradient it is known as osmosis. The dye particles also diffused against a high to low concentration gradient through the visking tubing which is not osmosis as it is the movement of particles rather than as the molecules were able to move through the semipermeable membrane whereas the sucrose solution particles are too large to diffuse through the semipermeable membrane of the visking tubing so they remain within the tubing. This causes the dye to move from within the tubing and out to the water and stain it with the dye colour while as the water moves into the tubing it expands and becomes more ridged.