Osmosis, surface and concentration of solution

Large potato
Sharp knife
Chopping board
Paper towels
Scales (0.1g resolution)
Beakers x 4
Stirring rod
Tea strainer

MethodCarefully cut five cubes of 2cm sides from the potato – ensure they have no skin on.
Dry and weigh the cubes.

In each of four beakers add 100ml of water. Add no salt to the first, weigh and add 5g to the next and so on up to 20g in the last. Stir to ensure all salt is dissolved.

Place a potato piece in each beaker, start the stopclock and time for 10 mins.

Pour each beaker out through a tea strainer – dry and weigh the pieces again.

Record the percentage mass increase, or decrease of each potato piece.


Knife must be used carefully – keep fingers well away from cutting surface. Glass beakers could break if not handled well, plastic beakers could be used for this experiment without any adverse effects.