. Explain Osmosis and Osmotic Pressure
The phenomenon of the passage of solvent molecules from a region of lower concentration (of the solution) to a region of its higher concentration or from pure solvent to solution through a semi-permeable membrane is called Osmosis.
Due to Osmosis, there is net movement of solvent is from the less concentrated (hypotonic) to the more concentrated (hypertonic) solution, which tends to reduce the difference in concentrations. This effect can be countered by increasing the pressure of the hypertonic solution, with respect to the hypotonic.
Thus, Osmotic Pressure (pie) can be defined as the external pressure which must be applied on the high concentration side to maintain equilibrium, and prevent the phenomenon of Osmosis with no net movement of solvent.
[Note: If the applied external pressure is more than the osmotic pressure then the solvent particles will start flowing in the opposite direction i.e., solution to solvent side(or high conc. to low conc. Side). This phenomenon is known as reverse osmosis.]