2.16 describe experiments to investigate diffusion and osmosis using living and non-living systems.

Diffusion in non-living
- Make agar jelly by mixing phenolphthalein and dilute sodium hydroxide (NOTE: The jelly will be pink from the phenolphthalein, incase you were wondering)
- Fill a beaker with dilute hydrochloride acid
- Cut different sized cubes (e.g 1x1cm, 2x2cm, 3x3cm) and put them in the dilute hydrochloric acid
- Leave the cubes for a whole

you should observe that they go colourless because the acid diffuses into the agar jelly


Osmosis in living
- cut a potato into 5 even cuboids, measure their lengths
- obtain 4 beakers wit different sugar solutions in them, and 1 with just watr (this will be our control)
- put each potato strip into one of the 5 beakers
- leave for 1 hour
- remove potato and measure strips again

Conclusion - if water has entered the potato, the length will be greater, if it has left, the length will be shorter (than before).


Osmosis in non-living

- tie a piece of string/wire around one end of some visking tubing and put a glass tube in the other, fixing it in place with more wire.
- pour sugar solution down the glass tube into the visking tubeing
- put the visking tubing into a beaker, fill the beaker with pure water and make a note of how far up the beaker the waterline sits
- leave the experiment overnight
- return the next day and measure the amount of water in the beaker

Conclusion - the water should have been drawn into the Visking tubing by osmosis, this will force the liquid up the glass tube