Osmotic pressure & Colloids

Osmosis is the movement of molecules from higher concentration to lower concentration via a semipermeable membrane. Osmotic pressure is the pressure required to stop osmosis.

1. Osmotic pressure XI FDC CHEMISTRY SIDRA JAVED

2. OSMOSIS The selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one.

3. OSMOTIC PRESSURE The pressure required to stop osmosis. The osmotic pressure of an ideal solution is given by MORSE EQUATION 𝜋 = M R T 𝜋 → OSMOTIC PRESSURE M → MOLARITY R = 0.082 dm 3 atmmol -1 K -1 T → absolute temperature

4. Tonicity Measure of the osmotic pressure of the two solutions separated by a semipermeable membrane There are 3 classifications of tonicity: Isotonic Hypertonic Hypotonic

5. Isotonic Two solutions which have equal concentration of solutes will have equal osmotic pressure are called isotonic solutions

6. Hypertonic Solution with a higher concentration of solute is called hypertonic solution

7. Hypotonic A solution with lower solute concentration is called a Hypotonic solution

8. Common applications of Osmotic Pressure Biochemist uses the haemolysis to study the contents of red blood cells. Haemolysis is the rupture of RBCs

9. Common applications of Osmotic Pressure Osmosis is the major mechanism of transporting water in plants.

10. Common applications of Osmotic Pressure Intracellular water tends to move out of bacterial cells to the concentrated solution by osmosis.

11. Common applications of Osmotic Pressure Food is preserved by osmosis.

12. REVERSE OSMOSIS Reverse osmosis is a membrane based filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane.

13. If an external pressure is applied on a concentrated solution, this pressure is distributed evenly throughout the solution If the applied pressure is higher than the osmotic pressure water will flow towards the other side of the membrane leaving solute behind This technique is used for purification of water

14. DESALINATION OF SEA WATER

15. Colloids & Suspensions

16. Colloids

17. Colloid A colloid is a dispersion of particles of one substance ( the dispersed phase ) throughout another substance or solution ( the dispersion phase ). A heterogeneous mixture of tiny particles of a substance dispersed through a medium is called colloidal dispersion or colloid.

18. Types of Colloids Lyophilic Colloids Lyophobic Colloids

19. Lyophilic vs Lyophobic Such colloidal dispersions in which dispersed phase shows an affinity or attraction for the dispersion medium are called Lyophilic Colloids Such colloidal dispersions which can not be made by spontaneous dispersion are called Lyophobic Colloids

20. Classification of colloids Based on Dispersed phase and dispersion medium: Sol - solid dispersed in a liquid Emulsion - liquid dispersed in a liquid Foam - gas particles are trapped in a liquid or solid. Aerosol - particles of liquid or solid dispersed in a gas.

21. Solid Sol Dispersed phase - solid Dispersion medium - solid Example - Ruby Glass

22. Solid Emulsion/ Gel Dispersed phase - Liquid Dispersion medium - solid Examples - Pearls , Cheese

23. Solid Foam Dispersed phase - Gas Dispersion medium - solid Examples - Lava

24. Sol Dispersed phase - Solid Dispersion medium - Liquid Examples - Paints

25. Emulsion Dispersed phase - Liquid Dispersion medium - Liquid Examples - Milk, Oil in Water

26. Foam Dispersed phase - Gas Dispersion medium - Liquid Examples - whipped cream

27. Aerosol Dispersed phase - Solid Dispersion medium - Gas Examples - Smoke

28. Aerosol Dispersed phase - Liquid Dispersion medium - Gas Examples - Fog, Mist

29. Properties of Colloids Mainly depends upon : Size of particles Shape of Particles Charge on Dispersed Particles

30. Colloids are generally opaque but some are transparent

31. Colloids exhibit Brownian Motion Colloids do not set under gravity

32. Colloidal particles they have charged surfaces which interact with molecules of dispersing medium

33. Temperature causes colloids to move faster and converts them into lumps. Example: coagulation of casein in milk

34. Colloidal particles can pass through ordinary filter paper but can not pass through ultra thin filter paper

35. Tyndall Effect

36. When light is shined through a true solution, the light passes cleanly through the solution. However when light is passed through a colloidal solution, the substance in the dispersed phases scatters the light in all directions, making it readily seen.

37. Suspension A dispersion in which the solute particle visible to the naked eyes are called suspension

38. Properties of Suspension Particle Size > 10 3 nm. Settle down under the influence of gravity. Suspension scatter and reflects light

39. Comparison of properties

40. END OF LESSON [email protected]