Activity 2.2 Let us experiment, To observe the effect of osmosis. Class 9

Activity 2.2 Let us experiment, To observe the effect of osmosis. Class 9

Activity 2.2 Let us experiment

Aim: To observe the effect of osmosis by studying the change in weight of potato pieces placed in plain water and concentrated salt/sugar solution.

Material Required: Potato, kitchen knife, beakers, water, salt or sugar solution and weighing balance.

Procedure:

1. With help of a knife, carefully cut a potato into two pieces of roughly equal size.
2. Measure and record the initial weight of both the pieces using a weighing balance.
3. Take two beakers marked with A and B.
4. Put one piece of potato in Beaker A with plain water.
5. Put the other piece of potato in Beaker B with 20 per cent salt and sugar solution.
6. Leave them undisturbed for about an hour or until you noticed a visible change in the size of the pieces.
7. Observe the difference between the initial and their final weights.

Observation:

1. Beaker A — The potato piece swells.
2. Beaker B — The potato piece shrinks.

The weight of potato piece in Beaker A has increased, while the weight of the potato piece in Beaker B has decreased.

Conclusion: The potato experiment demonstrates osmosis. Water moves from a dilute solution (plain water) into the potato cells, making them turgid, while it moves out of the potato cells in a concentrated salt/sugar solution, making them flaccid. This shows that water always moves from a higher water concentration to a lower water concentration through a semipermeable membrane.