Slide 1

There are no strict boundaries on the size of colloidal particles, but they tend to vary between 10-9 m to 10-6 m in size. Slide 2 Figure 17.22: The Tyndall effect Source: Stock Boston Slide 3 Slide 4 Figure 17.23: Representation of two colloidal particles Slide 5 Slide 6 Dispersing mediumDispersed phaseName Solid Solid sol SolidLiquidGel SolidGasSolid foam LiquidSolidSol Liquid Emulsion LiquidGasFoam GasSolidSolid aerosol GasLiquidAerosol Type of Colloids Slide 7 Aerosols: Man-made: Aerosol sprays, insecticide spray, smog. Natural: Fog, clouds. Solid aerosol: Natural: Smoke, dust. Foam: Man-made: Shaving lather, whipped cream. Emulsions: Man-made: Mayonnaise, cosmetic lotion, lubricants. Natural: Milk. Sols: Man-made: Paint, ink, detergents, rubber (a latex - also occur naturally). Solid foams: Man-made: Marshmallow, styrofoam, insulation, cushioning. Gels: Man-made: Butter, jelly. Solid sols: Man-made: Certain alloys. Natural: Pearl, opal. Biological macromolecules and cells may be considered to be biocolloids and many foods are also colloidal in nature. Colloids are also an important feature of the natural environment. Slide 8 Colloids in Paint and Food Slide 9 Cottrel precipitator installed in a smokestack. Slide 10 Magnetic liquid seal Slide 11 Slide 12 Surfactant Slide 13 cmc = critical micelle concentration Slide 14 Slide 15 Vesicles in Cell