Question

Define the terms:
(a) Semi-permeable membrane
(b) Osmosis

Answer 1

(a) Semi-permeable membrane: The movement of solvent molecules is allowed through a membrane (e.g. water molecules) but it prevents the movement of solute particles (e.g. sugar or salt molecules).

For example - egg membrane, parchment membrane, cellophane paper, etc. are semi-permeable membranes.

(b) Osmosis: A semi-permeable membrane through which the diffusion of water molecules from a region where water is more concentrated to a region where it is less concentrated is called osmosis. In other words, osmosis is the diffusion of water from its pure state or dilute solution into a stronger or concentrated solution through a semi-permeable membrane.