Osmotic Pressure

Hello everyone,

Today we will discuss about OSMOTIC PRESSURE.

Osmosis : 

We have observed that when we separate a dilute solution from a concentrated solution of the same type by a membrane, the solvent molecules flow from the dilute solution to the concentrated solutions. This movement continues until it reaches an equilibrium. This process of flow of solvent molecules due to the difference in concentration is osmosis.

Osmotic Pressure : 

Pressure applied on high concentration side to stop osmosis. It depends on number of moles of solute present in 1 litre.

                                          π = CRT

Where,

• π=osmotic pressure
• C=molarity of the solution
• R=Universal Gas constant:
• T=Temperature.      

Molarity is the number of moles of solute per litre of the solution. Suppose w₂ is the mass of solute having molar mass M₂ in a solution of volume V, then we can write,

                                             π=w₂RT/M₂V

Reverse Osmosis :  If pressure applied on high concentration side is more than osmotic pressure then flow of solvent occurs from high concentration side to low concentratio side.