Osmosis and Osmotic pressure
Osmosis and Osmotic pressure
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We have often observed that raw mangoes shrink when kept in salt water ( brine solution ), flowers remain fresh for longer time when kept in water .
This is due to the fact that small solvent molecules such as water are capable of passing through the pores present in every cell . These pores allows small solvents like water to pass through but hinders the passing of larger molecules . This membrane possessing such pore is known as semipermeable membranes .
The process of flow of solvents from the pure solvent to the solution through a semipermeable membrane is termed as osmosis .
This flow of solvents to the solution continues until the stage of equilibrium is reached .
Application of extra pressure on the solution can terminate the flow of solvents from the pure solvent to the solution . This pressure is called osmotic pressure of the solution . It is a colligative property that depends upon the concentration of the solution and is basically meant to stop the passage of solvent molecules through a semipermeable membrane into the solution .
Solvent molecules generally flows from lower concentration to higher concentration . This flow of solvent from dilute solution to the concentrated solution through a semipermeable membrane is due to the phenomenon of osmosis .
Number of moles of the polymer , n = 1 / 185000 mol Osmotic pressure ð ( n / V ) RT
Calculate the osmotic pressure in Pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL of water at 37 ° C .
Sol . Volume of water , V = 450 mL = 0.45 L
Temperature , T = ( 37 + 273 ) K = 310 K