Osmosis and Osmotic Pressure of the Solution

(a) Osmosis: The automatic and spontaneous flow of solvent from low to high concentration through a semipermeable membrane is called osmosis. A semipermeable membrane permits only solvent Of  solution to pass through. If a dried pea is placed in water it gets swelled after sometime due to inwardmovenent of water through its outer cell wall acting as an effective semipermeable membrane because it does not allow the 1nner material to go out. If an egg whose outer hard cell haS' been removed by diss’olving in conc. 'HCl, is placed in water, it gets membrane into the egg. But if such an egg is placed in saturated salt . solution, it gets shrinked due to the movement of the egg material from . ‘ low concentration to the salt of solution of high concentration. Similarly, “ the drowned animal body swells in Water due to osmosis. 

(b) Osmotic Pressure: When two solutions are separated by a semipermeable membrane, then there is a spontaneous and automatic flow of the solvent from low to high concentration due to osmosis. The pressure that must be applied on the solution of higher concentration to ‘ preventthe tlow of the solvent from the solution of lower concentration is called osmotic pressure of the solution. It is denoted by Π.

Osmosis and Osmotic Pressure of the Solution