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XII 02 Solutions IX
Osmosis and osmotic pressure:- Osmosis: When a semipermeable membrane is placed between the solution and the solvent molecules enter the solution and the volume of the solultion increases. The solvent molecules from solutilon of lower concentration moves towards solution of higher concentration.
Difference between Osinosis and diffusion: In diffusion, solute as well as solvent molecules flow in opposite directions while in osmosis the flow of solvent occurs in one direction only. (i) (i) For osmosis semipermeable membrane is required while for diffusion it is not required
Semi permeable membrance; A membrane which allows the solvent molecule to pass through it but prevents the passage of solute molecules through it is called a semipermeable memberane A sovent can pass through a semipermeabel membrance because the vapour pressure of the pure solvent is higher than the vapour pressure of the solution
Osmotic pressure The hydrostatic pressure developed as a result ofosmosis is a measure ofosmotic pressure ofthe solution Osmotic pressure is defined as the hydrostatic pressrue built up on the solution which just stops osmosis. . . Osmotic pressure-hydrostatic pressure h increase in level in the neck of this funnel d - density of solution g acceleration due to gravity. = CRT WB RT MB XV
Let two solutions of same substance having different osmotic pressures and 2 are mixed. Osmotic pressue of the resultant solution can be calculated as. I. Let n1 and n2 are the number of moles of two different solutes present in v1 and v2 volumes respectively. II. Where i and 2 are vant Hoff factor for two solutons