Question

In an experiment setup, a dye was placed at the bottom of a beaker filled with water as shown in figure A, below. After some time, the entire water in the beaker got coloured uniformly as shown in figure D.

(a) Name and define the phenomenon in the experiment.
(b) In all the figures, two kinds of molecules are shown symbolically larger and smaller. Which molecules are of the solute and which are of the solvent.
(a) Larger: (b) Smaller:
(c) If all the dark molecules in A are tightly enclosed in a cell membrane, what will be the nature of the movement of the molecules, if any?

Answer 1

(a) The process is diffusion.
Diffusion is the movement of the substances from higher to lower concentrations.

(b)
(a) The larger molecules are of the solute (dye).
(b) The smaller molecules are of the solvent (water).

(c) The cell membrane will act as a semi-permeable membrane and will allow only the solvent molecules to move towards the solute particles. This process is called osmosis.