Question

Describe thistle funnel experiment to demonstrate osmosis with a labelled diagram

Answer 1

Experiment: To demonstrate osmosis using thistle funnel

Requirements: glass beaker, thistle funnel, a sheet of cellophane, thread, water, and sucrose or sugar solution.

Procedure

i) Thistle funnel is filled with sucrose solution and its mouth is tied with a parchment paper.

ii) Thistle funnel is kept inverted in a glass beaker that contains water.

iii) The initial level of sucrose is noted down.

iv) After some time the sucrose solution rises in the stem of a funnel that indicates that osmosis has occurred.

Observations: The level of water in thistle funnel increases.

Results: i) Movement of water through the cellophane sheet to thistle funnel can be seen.

ii) Water moves from the region of higher concentration to lower concentration.

iii) The movement water occurs through a semi-permeable membrane.

iv) The force due to which the solution in the tube increases is due to osmotic pressure.

v) Stability of water level in the funnel shows that water concentration in both the beakers as well as the funnel is the same and so osmosis stop.